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The suitability of continuous laminated veneer lumber production to some Canadian wood species Afolayan, Ademola Adeniyi 1974

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I THE SUITABILITY OF CONTINUOUS LAMINATED VENEER LUMBER PRODUCTION TO SOME CANADIAN WOOD"SPECIES by ADEMOLA ADENIYI AFOLAYAN B. Sc. (Hons.) F o r e s t r y , U n i v e r s i t y of Ibadan, 1970 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF FORESTRY i n the Department of F o r e s t r y We accept t h i s t h e s i s as conforming t o the req u i r e d standard THE UNIVERSITY OF BRITISH COLUMBIA October, 1974 In p resent ing t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the requirements f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r reference and study. I f u r t h e r agree t h a t permiss ion fo r e x t e n s i v e copying o f t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head of my Department or by h i s r e p r e s e n t a t i v e s . It i s understood that copying or p u b l i c a t i o n of t h i s t h e s i s f o r f i n a n c i a l ga in s h a l l not be a l lowed without my w r i t t e n p e r m i s s i o n . I Department of F o r e s t r y The U n i v e r s i t y of B r i t i s h Columbia Vancouver 8, Canada Date 2 3 - 1 0 - 1 9 7 4 ABSTRACT Laminated veneer lumber was made by g l u i n g s i x l a y e r s of ^ i-inch veneer assembled w i t h g r a i n d i r e c t i o n s p a r a l l e l and a l l the t i g h t veneer surfaces outward. A s p e c i a l l y modified phenol-formaldehyde plywood r e s i n was used. Shear strength and wood f a i l u r e of specimens t e s t e d dry, and a f t e r a c c e l e r a t e d aging, were used to evaluate bond q u a l i t y . L i m i t e d samples of broadleaf maple laminated veneer lumber were used to demonstrate t h a t , w i t h c e n t r a l g l u e l i n e j u s t reaching 240°F before opening the press, adequate bonds were formed. These were not s i g n i f i c a n t l y d i f f e r e n t from those produced w i t h a c e n t r a l g l u e l i n e temperature reaching 300°F. Tests of specimens from small panels of broadleaf maple, black cottonwood, and sugar maple p r w d t h a t a gluespread of at l e a s t 42.5 pounds per thousand square f e e t of s i n g l e g l u e l i n e (42.5 lb/MSGL) was r e q u i r e d . At t h i s spread, a c e n t r a l g l u e l i n e temperature of 240°F and p l a t e n temperature of 350°F, adequate bond q u a l i t y was produced at p l a t e n pressures of 200 p s i , 100 p s i and 275 p s i f o r broad-l e a f maple, b l a c k cottonwood and sugar maple, r e s p e c t i v e l y . Based on the press schedules developed w i t h the small panels, black cottonwood, sugar maple, and white spruce, continuous laminated veneer lumber boards were manu-i i f a c t u r e d , using the process described by Bohlen i n 1972. Only the white spruce boards produced adequate bonds. Those of black cottonwood and sugar maple f a i l e d due to dry-out of glue adjacent to the p l a t e n s . Although s u i t a b l e pressing c o n d i t i o n s were worked out f o r single-pressed boards, i r r e s p e c t i v e of wood species, the glue would need f u r t h e r m o d i f i c a t i o n f o r the hardwoods studied to be used f o r continuously produced laminated veneer lumber. i i i ACKNOWLEDGEMENTS Thankful acknowledgement i s made to Dr. W. V. Hancock, research s c i e n t i s t at the Western Forest Products Laboratory, Vancouver, f o r sup e r v i s i n g t h i s t h e s i s p r o j e c t . H i s c o n s t r u c t i v e c r i t i c i s m s are appreciated and h i s personal f r i e n d s h i p was a great encouragement. Thanks are expressed t o Mr. L. V a l g , A s s i s t a n t Professor i n the F a c u l t y of F o r e s t r y i n the U n i v e r s i t y of B.C. His c o n t r i b u t i o n s as f a c u l t y advisor and committee chairman f o r the author are appreciated. Dr. N. C. Franz, Professor i n the F a c u l t y of F o r e s t r y i n the U n i v e r s i t y of B.C., was a great help i n the prepara-t i o n of, t h i s t h e s i s . H is p o s i t i o n i n the author's committee i s a p preciated. The c o n t r i b u t i o n of Dr. R. W. Wellwood at the e x p e r i -mental stage of t h i s study i s acknowledged. Thankful acknowledgement i s made to Dr. A. Kozak, Bi o m e t r i c s professor at the U n i v e r s i t y of B.C. f o r - h i s advice on the s t a t i s t i c a l a n a l y s i s . The a s s i s t a n c e o f f e r e d by the t e c h n i c a l s t a f f of the WFPL's Plywood S e c t i o n , and the Biometrics t e c h n i c i a n s of the F a c u l t y of F o r e s t r y i n the U n i v e r s i t y of B.C. are appreciated. The author wishes t o thank the Canadian I n t e r n a t i o n a l Development Agency f o r h i s f i n a n c i a l support f o r higher education i n Canada. The l o v i n g and p r a y e r f u l support of the author by h i s w i f e , parents and many f r i e n d s are h i g h l y appreciated. i v TABLE OF CONTENTS Page TITLE PAGE i ABSTRACT i i ACKNOWLEDGEMENTS i v TABLE OF CONTENTS v LIST OF TABLES x LIST OF FIGURES : x i v 1.0 INTRODUCTION 1 1.1 Towards B e t t e r U t i l i z a t i o n of Wood Raw M a t e r i a l 1 1.2 Background, Objectives and Scope. . . . 5 1.3 C r i t i c a l P o i n t s i n the Continuous LVL Production Process. . . 6 2.0 LITERATURE REVIEW 8 2.1 Development and S p e c i a l Advantages. . . 8 2.2 Economic F e a s i b i l i t y 11 2.3 Tec h n i c a l F e a s i b i l i t y 13 2.4 G l u a b i l i t y . 20 2.5 The Laminating Process 24 3.0 MATERIALS AND METHODS 26 3.1 Veneer 26 3.1.1 Broadleaf Maple 26 3.1.2 Sugar Maple 26 3.1.3 Black Cottonwood 27 3.1.4 White Spruce 30 v Page 3.2 Glues 30 3.2.1 IB-337 Plyophen 31 3.2.2 IB-334 Plyophen 32 3.2.3 Cascophen 904-003-Catalyst 400-040 (2600-CR40) 32 3.3 Experimental Procedure 33 3.3.1 Aspects of the Study 33 3.3.2 Experimental Design 33 3.3.2.1 Small panel t e s t s 33 3.3.2.2 Continuous LVL t e s t s 35 3.3.3 Panel C o n s t r u c t i o n and C o n d i t i o n i n g . . . 36 3.3.3.1 Veneers f o r small panel s-, .,• . . . . . 36 3.3.3.2 G l u i n g of small panels . 37 3.3.3.3 Quantity and c h a r a c t e r i s t i c s of veneers used f o r the continuous LVL production "38 3.3.3.4 Gluing of continuous LVL boards. . . 39 3.3.4 Specimen P r e p a r a t i o n 40 3.3.4.1 Shear blocks .from small panels . . . _40 3.3.4.2 Shear blocks from continuous LVL boards 41 3.3.5 Testing Procedure 42 3.3.5.1 Dry shear t e s t 42 3.3.5.2 Cold soak 4 2 ' 3.3.5.3 C y c l i c (vacuum/pressure) soak t e s t . 43 3.3.5.4 Delamination t e s t 44 3.3.5.5 B o i l t e s t 45 3.3.5*6 Shear strength adjustment 45' 4.0 RESULTS 47 4.1 Small Panel Tests. 47' v i Page 4.1.1 G l u e l i n e Temperature of Broadleaf Maple, Black Cottonwood and Sugar Maple LVL. . . 47 4.1.2 Adequate Gluing C o n d i t i o n s f o r Broadleaf Maple 47' . 4.1.3 Adequate Glu i n g C o n d i t i o n s f o r Black Cottonwood. LVL 48 4.1.4 Adequate Gluing C o n d i t i o n s f o r Sugar Maple LVL . .49"' 4.1.5 Performance of Phenol-Resorcihol Glue i n Sugar JVIa pie and Black Cottonwood LVL. . . 49 4.2 Continuous LVL Tests 49 4.2.1 Mean Values f o r Continuous LVL Sections . 49 4.2.2 G l u e l i n e Temperature of Continuous LVL. . 50 4.2.3 Strength Q u a l i t y Response t o Continuous ' Laminating Process. . . . . . . . . . . . . ,50" 4.2.4 Delamination Test 50' 5.0 DISCUSSION 51 5.1 Small Panel Tests 51 5.1.1 Press Schedule f o r Broadleaf Maple. . . . 51 5.1.2 Adequate Gluespread f o r Broadleaf Maple LVL 52 5.1.3 E f f e c t of P l a t e n Temperature 55 5.1.4 Adequate Curing Temperature 55 5.1.5 E f f e c t of P l a t e n Pressures 57 V i i Page 5.1.6 Black Cottonwood and Sugar Maple Studies .58 5.1.6.1 Press schedules f o r black cottonwood and sugar maple LVL 59 5.1.7 Adequate Gluespread f o r Black Cottonwood LVL 60' 5.1.8 Adequate P l a t e n Pressure f o r Black Cottonwood LVL . . . . . . 61 5.1.9 Adequate Gluespread f o r Sugar Maple LVL. 63 5.1.10 Adequate P l a t e n Pressure f o r Sugar Maple LVL .64' 5.1.11 Small Panel Study, Summary and Comments. 65 5.1.12 Adequate Gluespread Phenol-Resorcinol-Glue w i t h Sugar Maple. 66 5.1.13 Bond Strength w i t h Black Cottonwood. . . .68 5.1.14 E f f e c t of Double-Pressing '69 5.2- Continuous LVL Study . 70 5.2.1 Average Strength C h a r a c t e r i s t i c s of Board S e c t i o n s . . 70 5.2.2 Strength Q u a l i t y Response to the Continu-ous Board Laminating Process 73 5.2.2.1 G l u e l i n e temperature along l e n g t h of boards. 73 5.2.2.2 G r a p h i c a l i l l u s t r a t i o n of bond q u a l i t y of c e n t r a l g l u e l i n e . . . . . 75 5.2.2.3 Delarnination t e s t 77 v i i i Page 5.2.2.3.1 C y c l i c vacuum/pressure delamina-t i o n (CS.A 0177-1965) 77 6.0 CONCLUSION 82 7.0 RECOMMENDATIONS -85 8.0 LITERATURE CITED 85 9.0 TABLES 94 10.0 FIGURES 133 11.0 APPENDICES 153 i x LIST OF TABLES Table Page 1. Frequency of grades of black cottonwood ^ - i n c h veneers peeled f o r the study . . . 95 2. Average green moisture content of black cottonwood ^i-inch veneers 96 3. Design of small panel experiments . . . . 97' 4. Factors examined i n the small panel experiments 99 5. Some c h a r a c t e r i s t i c s of ^ - i n c h veneers used i n t h i s study 100 6. Shear b l o c k samples f o r the small panel t e s t s 101 7. C e n t r a l g l u e l i n e temperature r i s e of phenolic glue IB-337-bonded broadleaf maple LVL 102 8. G l u e l i n e temperature i n 6-ply Laminated Veneer Lumber at v a r i o u s l e v e l s of gluespread 103 9. Testing broadleaf maple LVL f o r adequate gluespread 104 10. Mean and v a r i a b i l i t y of three strength p r o p e r t i e s of broadleaf maple LVL t e s t e d f o r adequate gluespread 105 x Table Page 11. Mean and v a r i a b i l i t y of three strength p r o p e r t i e s of broadleaf maple LVL t e s t e d f o r four gluespreads 106 12. Testing broadleaf maple LVL f o r e f f e c t of p l a t e n temperature 107 13. Mean and v a r i a b i l i t y of three strength p r o p e r t i e s of broadleaf maple LVL tes t e d f o r e f f e c t of p l a t e n temperature . 108 14. Testing broadleaf maple LVL f o r adequate c u r i n g temperature . . . . . . . . 109 15. Mean and v a r i a b i l i t y of three strength p r o p e r t i e s of broadleaf maple LVL te s t e d f o r adequate c u r i n g temperature. . 110 16. E f f e c t of pressure on c e r t a i n c h a r a c t e r -i s t i c s of broadleaf maple LVL I l l 17. Testing black cottonwood f o r adequate gluespread of phenolic r e s i n glue IB-337. . . . . 112 18. Mean and v a r i a b i l i t y of some strength p r o p e r t i e s of black cottonwood LVL at d i f f e r e n t l e v e l s of gluespread 113 19. Testing black cottonwood LVL f o r e f f e c t of pressing at 69 and 100 p s i r e s p e c t i v e l y . 114 x i -Table Page 20. Mean and v a r i a b i l i t y of some strength p r o p e r t i e s of black' cottonwood at two l e v e l s of pl a t e n pressure 115 21. Testing sugar maple LVL f o r adequate gluespread of phenolic r e s i n glue IB-337 . 116 22. Mean and v a r i a b i l i t y of some strength p r o p e r t i e s of sugar maple LVL at d i f f e r e n t l e v e l s of gluespread 117 23. Testing sugar maple LVL f o r e f f e c t of pressing at 250 and 275 p s i , r e s p e c t i v e l y . 118 24. Mean and v a r i a b i l i t y of some strength ' p r o p e r t i e s of sugar maple LVL at two l e v e l s of pl a t e n pressure 119 25. E f f e c t of pressing time and glue on some streng t h and r e l a t e d p r o p e r t i e s of sugar maple LVL . . . . . . . . . 120 26. Mean and v a r i a b i l i t y of some strength and r e l a t e d p r o p e r t i e s of sugar maple LVL as a f f e c t e d by pressing time and type of glue 121 27. Testing sugar maple LVL f o r adequate gluespread w i t h p h e n o l - r e s o r c i n o l glue 122 x i i Table Page 28. Mean and v a r i a b i l i t y of some strength p r o p e r t i e s of p h e n o l - r e s o r c i n o l bonded sugar maple LVL at two l e v e l s of gluespread 123 29. Testing b l a c k cottonwood LVL f o r bond q u a l i t y w i t h p h e n o l - r e s o r c i n o l , glue 124 30. Mean and v a r i a b i l i t y of three strength p r o p e r t i e s of p h e n o l - r e s o r c i n o l : bonded black cottonwood LVL 125 i 31. Mean and v a r i a b i l i t y of some strength and r e l a t e d p r o p e r t i e s of the three s e c t i o n s of continuous LVL 126 32. G l u e l i n e temperature i n continuous LVL at v a r i o u s p o i n t s along the board . . . . 128 33. C y c l i c vacuum/pressure/dry delamination of LVL 129 34. B o i l / d r y / b o i l delamination of PF IB-334-bonded LVL 130 35. Comparison of shear strength of phenolic glue IB-337-bonded LVL w i t h published data on s o l i d sawn lumber 131 36. Performance of continuous LVL c e n t r a l g l u e l i n e according t o P.S. 56-73 ^32 x i i i LIST OF FIGURES Figure Page 1. Veneer arrangement i n continuous LVL. . . . 134 2. L o c a t i o n of thermocouples i n g l u e l i n e s of continuous LVL 135 3. A 16-foot continuous LVL board 136 4. Small panels constructed f o r the v a r i o u s t e s t s 137 5. C u t t i n g f o u r - i n c h s t r i p s from f u l l s i z e veneers. . . . . . . . . 138 6. C u t t i n g of veneer q u a l i t y specimens from l a r g e veneer sheets f o r the c o n t i n u -ous LVL 139 7. C u t t i n g the s t a r t e r and end boards from one set of f u l l l e ngth ^ - i n c h - t h i c k veneers 140 8. Temperature r i s e at geometric centre of inner and outer g l u e l i n e s of broadleaf maple Laminated Veneer Lumber 141 9. Temperature r i s e at three c r i t i c a l p o i n t s i n the LVL lay-up i n the continuous board production process. 142 10. Black cottonwood LVL strength q u a l i t y response t o continuous laminating process using phenol-formaldehyde glue IB-337 . . . I43 •x i v Figure Page 11. Black cottonwood LVL strength q u a l i t y response to continuous laminating process using phenol-formaldehyde glue IB-337 144 12. Black cottonwood LVL strength q u a l i t y response t o continuous laminating process using phenol-formaldehyde glue IB-334 145 13. Black cottonwood LVL strength q u a l i t y response t o continuous laminating process using phenol-formaldehyde glue IB-334 146 14. Sugar maple LVL strength q u a l i t y response t o continuous laminating process using phenol-formaldehyde glue IB-337 147 15. Sugar maple LVL strength q u a l i t y response t o continuous laminating process using phenol-formaldehyde glue IB-337 148 16. Sugar maple LVL strength q u a l i t y response t o continuous laminating process using phenol-formaldehyde glue IB-334 . 149 X V i Figure Page 17. Sugar maple LVL strength quality-response t o continuous laminating process using phenol-formaldehyde glue IB-334 150 18. White spruce LVL strength q u a l i t y response t o continuous laminating process using phenol-formaldehyde glue IB-337 151 19. ' White spruce LVL strength q u a l i t y response t o continuous laminating process using phenol-formaldehyde glue IB-337 152 x v i 1 1.0 INTRODUCTION 1.1 Towards B e t t e r U t i l i z a t i o n of Wood Raw M a t e r i a l The production of s t r u c t u r a l lumber by laminating t h i c k - p e e l e d veneers has made p o s s i b l e the conversion of low-grade or small logs i n t o high-value f o r e s t products. Work on t h i s product dates back to the Second World War but i t s economic p o t e n t i a l has been doubted f o r many years. Recent stud i e s on manufacture of Laminated Veneer Lumber (LVL) at the Western Forest Products Laboratory i n Vancouver, and of Pres-Lam at the U.S. Forest Products Laboratory, Madison, Wisconsin, i n d i c a t e the p o t e n t i a l can be r e a l i z e d . Wood i s a v e r s a t i l e engineering and c o n s t r u c t i o n m a t e r i a l which i s i n e v e r - i n c r e a s i n g world demand. In the l a s t two decades, lumber production i n B r i t i s h Columbia (B.C.) has increased both i n t o t a l volume and as a percentage of t o t a l Canadian output. In 1952, t o t a l volume of sawn lumber produced i n B.C. was 3.7 b i l l i o n fbm and i n 1971 9.0 b i l l i o n fbm. This represents a 143 percent increase i n production. In the two years, B.C. production was 54 and 69 percent, r e s p e c t i v e l y , of t o t a l Canadian production (Government of B.C., 1972). The growing need f o r , and e x p l o i t a t i o n of, timber may lead to problems r e l a t i n g to inventory such as a general decrease of the wood bank 2 (standing stock) and a probably e q u a l l y important problem of d i s r u p t i n g the species balance due to over e x p l o i t a t i o n of the more a c c e s s i b l e and favoured species. U n t i l 1966, Douglas f i r (Pseudotsuga m e n z i e s i i Mirb. Franco) was the p r i n c i p a l species harvested i n B.C. (Govern-ment of B.C., 1972), although more recent s t a t i s t i c s (Dobie 1970) show t h a t , on the coast, D o u g l a s - f i r formed only the f i f t h highest species i n inventory volume while i t was second highest i n 1968 cut. True f i r and lodgepole pine which were, r e s p e c t i v e l y , , t h i r d and f o u r t h highest species i n inventory volume, were f i f t h and s i x t h highest i n the 1968 cut. The D o u g l a s - f i r cut was therefore f a r out of p r o p o r t i o n to the supply while true f i r and lodgepole pine were cut f a r l e s s than was j u s t i f i e d by the pr o p o r t i o n they form of the inventory. This o v e r c u t t i n g of D o u g l a s - f i r has had a s i g n i f i - ^ cant impact on wood products manufacturing i n B.C. D o u g l a s - f i r i s w e l l known i n the i n t e r n a t i o n a l market f o r i t s s t e r l i n g q u a l i t i e s which i n c l u d e good work-a b i l i t y , ease of p e e l i n g , ease of treatment (except the mountain t y p e ) , and, e s p e c i a l l y , strength. A l s o , long experience w i t h use has l e d to a v a i l a b i l i t y of extensive s c i e n t i f i c data on D o u g l a s - f i r . Probably an important point i n market development was the ready a v a i l a b i l i t y of la r g e c l e a r s i z e s of coast D o u g l a s - f i r i n the e a r l y days of e x p l o i t a t i o n . Owing to these f a c t o r s of long usage experience, good performance and a v a i l a b i l i t y , a whole 3 plywood i n d u s t r y developed around t h i s s i n g l e species. Over the years, the housing and other panel and lumber using i n d u s t r i e s have developed a preference f o r Douglas-f i r . A shortage of r e a d i l y a v a i l a b l e o l d growth Douglas-f i r , and the general change i n inventory balance has forced the f o r e s t i n d u s t r y i n B.C. to take c o r r e c t i v e steps., These inc l u d e d i v e r s i f i c a t i o n of the raw m a t e r i a l base f o r lumber through i n t r o d u c t i o n and promotion of new species, a progressive phasing out of the D o u g l a s - f i r base f o r the softwood plywood i n d u s t r y , c l o s e r u t i l i z a t i o n of a v a i l a b l e raw m a t e r i a l , u t i l i z a t i o n of second growth D o u g l a s - f i r and of i n f e r i o r s p e c i e s , and so of smaller and smaller logs f o r making plywood. They have f i t t e d w e l l w i t h the general trend i n the i n d u s t r y toward sheathing plywood production and away from sanded f i n i s h grades. Economic u t i l i z a t i o n of poorer q u a l i t y m a t e r i a l , which now forms the bulk of a v a i l a b l e timber, has al s o been enhanced. The concept of r o t a r y p e e l i n g of small logs as a cheaper raw m a t e r i a l source and of laminating the m a t e r i a l i n t o s t r u c t u r a l lumber was examined by the Canadian Western Forest Products Laboratory s t a f f as a p o s s i b l e s o l u t i o n to the problem of f a l l i n g l o g s i z e s and q u a l i t i e s . I t a l s o promised to o f f s e t the a d d i t i o n a l c o s t s due to the more s t r i n g e n t demands of close u t i l i z a t i o n made on i n d u s t r y by government. The laminating process makes p o s s i b l e the production of l a r g e , high grade s t r u c t u r a l components w h i l e 4 u t i l i z i n g small or poor q u a l i t y l o g s . In the United S t a t e s , i t was developed i n a n t i c i p a t i o n of greater pressures from the environmental-i s t s who advocate wilderness development, and might succeed i n f o r c i n g the government to reduce the s i z e of concessions a l l o t t e d to the f o r e s t i n d u s t r i e s ( S c h a f f e r , et a l . 1972). The socio-economic as w e l l as f o r e s t inventory problems of developing nations provide an even greater i n c e n t i v e f o r e x p l o r i n g a l l avenues of improving raw m a t e r i a l u t i l i z a -t i o n . As an example of se r i o u s inventory problems, N i g e r i a ' s s i t u a t i o n can be c i t e d . Forest land accounts f o r only 35 percent of t o t a l land area (Enabor 1973), and i s covered by a heterogeneous mixture of speci e s . B r i t i s h Columbia's f o r e s t s depend on seven major specie s , a l l of which are s u i t a b l e f o r timber production. Nearly 600 species a t t a i n merchantable s i z e i n N i g e r i a n f o r e s t s of which only about 24 are c u r r e n t l y acceptable i n the i n t e r n a t i o n a l timber market. The N i g e r i a n f o r e s t i n d u s t r y does not face pressures from e n v i r o n m e n t a l i s t s at present but there i s great competition f o r , and encroachment i n t o , f o r e s t lands by the a g r i c u l t u r a l sector of the economy. I t i s t h e r e f o r e probable t h a t , i f the N i g e r i a n f o r e s t i n d u s t r y i s t o survive i t must l e a r n and b e n e f i t from the North American experience by developing such products as LVL or Pres-Lam which make p o s s i b l e b e t t e r raw m a t e r i a l u t i l i z a t i o n . 5 1.2 Background, O b j e c t i v e s and Scope As part of a course of d i r e c t e d s t u d i e s , the author f a b r i c a t e d LVL from t h i c k veneer of broadleaf maple (Acer  macrophyllum Pursh.). using step-pressing as described by Bohlen (1972a). S u i t a b l e t e s t specimens were prepared and stressed to f a i l u r e i n bending. I t was found that some strength c h a r a c t e r i s t i c s exceeded those of broadleaf maple s o l i d lumber, while some were s l i g h t l y lower. Some glue f a i l u r e at the step j o i n t s was discovered. The f i n d i n g s brought i n t o question the s u i t a b i l i t y of some hardwoods f o r LVL produced as "endless"''" boards. The o r i g i n a l i n t e n t i o n was to examine three t r o p i c a l hardwoods of low, medium and high d e n s i t y , and i determine t h e i r s u i t a b i l i t y f o r LVL. E f f o r t s to obta i n t r o p i c a l species f a i l e d and th e r e f o r e Canadian species were used. These included broadleaf maple (veneers saved from the e a r l i e r experiments), b l a c k cottonwood (Populus t r i c h o -carpa Torr. and Gray) and sugar maple (Acer saccharum Marsh). The Eastern Forest Products Laboratory s u p p l i e d dry 0.273" (^-inch nominal) sugar maple veneer. A l s o , some white spruce (Picea qlauca Moench Voss) veneers, from previous l a b o r a t o r y s t u d i e s , were a v a i l a b l e i n l i m i t e d q u a n t i t i e s and were used as c o n t r o l s . Black cottonwood and sugar maple were, t h e r e f o r e , the main species studied. •*"A term used to describe continuous long beams made by end j o i n t i n g r e l a t i v e l y short laminates. 6 The experiments were designed to determine adequate gluespreads, c u r i n g temperature and p l a t e n pressure. Temperature r i s e w i t h i n boards i n the press and i n the stepped j o i n t s e x t e r n a l to the platens were a l s o measured i n order to determine press-schedules. The q u a l i t y of the c e n t r a l g l u e l i n e was studied w i t h a standard plywood phenolic r e s i n g l u e ^ and w i t h the same glue modified f o r dryout r e s i s t a n c e . Bonds produced w i t h p h e n o l - r e s o r c i n o l r e s i n were used as a standard. 1.2 C r i t i c a l P o i n t s i n the Continuous LVL Production Process The laminating process described by Bohlen (1972a) included g l u i n g of veneers t h a t protruded from between the pla t e n s , d u r i n g press closure,.for s i x to 30 inches. In p r i n c i p l e , the board s e c t i o n adjacent to the edge of the platens should promote a c a n t i l e v e r e f f e c t , thereby f u r n i s h -ing adequate pressure r e q u i r e d f o r adhesion during p r e s s i n g . Sections f u r t h e r away are subject to abnormally long (not l e s s than 20 minutes) closed assembly time. E i t h e r the glue should have a high dry-out t o l e r a n c e or the veneer should have a low absorptive c a p a c i t y f o r glue i n order t o ensure adequate bonds i n the step j o i n t s . ( Figures 1 and 2 show the step j o i n t s which s t i c k out of the p l a t e n s . ) ' A l s o , the glue should not precure i n the step Phenol-formaldehyde glue IB-337 was manufactured by Reichhold Chemicals (Canada) L i m i t e d . 7 j o i n t s at the temperatures p r e v a i l i n g c l o s e to the pla t e n edge. Bohlen (1972a) reported that adequate bonds were formed i n the D o u g l a s - f i r LVL w i t h the glue s p e c i a l l y modified by the manufacturer. Because the veneers are u s u a l l y shorter than the press p l a t e n s , sections adjacent to the step j o i n t s are u s u a l l y pressed twice (see f i g u r e 3 ) . While the process appears t o be r e l a t i v e l y simple, economical, and proven f o r D o u g l a s - f i r LVL, i t i s not known i f i t would be s u i t a b l e f o r other species. I t i s al s o not known i f the pressing regime used w i l l have an adverse e f f e c t on the p h y s i c a l p r o p e r t i e s of the f i n i s h e d m a t e r i a l i n s e r v i c e so as to l i m i t engineering a p p l i c a t i o n s . 8 '2.0 LITERATURE REVIEW 2.1 Development and S p e c i a l Advantages S t r u c t u r a l m a t e r i a l laminated from t h i c k - p e e l e d veneers was reported during the second world war by Luxford (1944). The f e a s i b i l i t y of commercial production of the new wood product was viewed w i t h pessimism (Bohlen 1973) u n t i l r e c e n t l y . I n t e n s i f i e d research and development are showing t h a t , according t o Bohlen, the "voices of gloom who declare such a m a t e r i a l too expensive are not n e c e s s a r i l y c o r r e c t . " The current production techniques d e r i v e l a r g e l y from the pioneering work of Marra (1956) and McKean and Smith (1958) who developed techniques f o r r a p i d l y laminating one-inch-thick lumber. L e i c e s t e r and Bunker ( l 9 6 8 ) , using to t w o - i n c h - t h i c k s o l i d lumber l a m i n a t i o n s , demonstrated th a t the t h i n n e r the laminations the higher the f r a c t u r e s t r e s s . Westman and Nemeth (1968) a l s o used t h i n s o l i d lumber (5 / 8 - i n c h - t h i c k ) to compare s i n g l e and 2-ply laminated t e n s i o n v a l u e s . The research reported by Koch (1964, 1965) and Murphey et al.(1967) i n v o l v e d laminating slicewood. According t o Koch (1967), i n terms of veneer y i e l d and u t i l i -z a t i o n of b o l t s shorter than ei g h t f e e t , r o t a r y peeling i s to be p r e f e r r e d t o s l i c i n g . For t h i s reason, most l a t e r 1 workers concentrated on laminating rotary-peeled veneers. Slicewood i s t h i n lumber cut from the side of a squared b i l l e t through an up and down, h o r i z o n t a l or r o t a r y ( i n some German machines) movement of a heavy k n i f e . 9 Koch (1967) and Koch and Woodson (1968) made very strong 42-ply beams from l / 6 - i n c h r o t a r y cut southern pine (Pinus spp.) veneers, using a p h e n o l - r e s o r c i n o l formaldehyde glue and a screw operated c o l d press. Hann et a l . (1971) developed the Pres-Lam process f o r manufactur-ing red oak (Quercus sp.) laminated boards f o r p a l l e t deck boards. Bohlen (1972a) published the r e s u l t s of research done at the Western Forest Products Laboratory on produc-t i o n of Douglas f i r LVL. An e l a b o r a t i o n of the process, w i t h a q u a l i t y c o n t r o l programme of the wood product (Bohlen 1973) was presented at the IUFRO conference i n Capetown, South A f r i c a , l a t e r . He described the wood product as continuous wide planks, up to 48 inches wide, formed by g l u i n g together i n - u n i d i r e c t i o n a l / m u l t i p l e l a y e r s ^ - i n c h - t h i c k rotary-peeled veneers w i t h phenol-formaldehyde waterproof adhesive. Schaffer et a l . (1972,/) improved the Pres-Lam technology and modified the schedules i n i t i a l l y designed f o r red oak, t o f a c i l i t a t e production of s t r u c t u r a l m a t e r i a l from southern pines. According t o these workers "Pres-Lam i s an in t e g r a t e d processing system to convert l o g s i n t o continuous t h i c k laminated sheets more e f f i c i e n t l y and r a p i d l y than any processing schemes c u r r e n t l y used." I t employs the r e s i d u a l heat of drying ^ - t o one-inch-thick rotary-peeled veneers t o cure the ph e n o l - r e s o r c i n o l laminating glue i n two t o four minutes of pressing without a d d i t i o n a l heat. 10 Koch (1973) suggested a two-stage laminating process f o r rotary-peeled J^-inch southern pine veneers. The f i r s t stage would i n v o l v e hot laminating veneers i n t o 3-ply beams w i t h standard phenol-formaldehyde glue, probably as i n the LVL system, while the second stage would i n v o l v e c o l d laminating the 3-ply boards in. p a i r s w i t h p h e n o l - r e s o r c i n o l glue. In the general summary of the Pres-Lam f e a s i b i l i t y study, Schaffer et a l . (1972) gave the s p e c i a l f e a t u r e s of Veneer-Lumber laminated from rotary-peeled veneers. These in c l u d e r e d i s t r i b u t i o n of strength-reducing d e f e c t s , absence of j u v e n i l e wood from f i n i s h e d products, u t i l i z a t i o n of short b o l t s , p o s s i b i l i t y of producing wide, continuous beams, ease of p r e s e r v a t i v e treatment through the access routes of l a t h e checks. Pres-Lam i s c h a r a c t e r i z e d by a f a s t production speed from b o l t to f i n i s h e d lumber of l e s s than one hour. Bohlen (1972a) discussed the p o s s i b i l i t y of p r e f a b r i c a t i o n of s t r u c t u r a l components of unconventional design. He c i t e d the manufacture of a geodesic space frame from curved LVL by the a r c h i t e c t u r e students of the U n i v e r s i t y of B.C. Koch (1967) demonstrated the p o t e n t i a l of producing superstrength lumber through d e n s i f i c a t i o n and l o c a t i o n of veneers by s t i f f n e s s . He demonstrated the p o s s i b i l i t y of f a b r i c a t i n g a seven-inch deep beam, and Bohlen (1972a) suggested the p o s s i b i l i t y of v e r t i c a l laminat-ing nominal two-inch LVL i n t o l a r g e s t r u c t u r a l s i z e s l i k e 9 x 48-inch x 80-feet. 11 Koch (1967), Koch and Woodson (1968), Moody (1972) , Bohlen (1972a, 1973, 1974) agree t h a t laminating t h i n veneers r e s u l t s i n m a t e r i a l w i t h superior s t r e n g t h . Others such as Luxford (1944), Norton (1943), U.S. Forest Products Laboratory (1966) found no s p e c i a l strength improvement, while s u b s t a n t i a l r e d u c t i o n of some strength p r o p e r t i e s have been reported by Lutz et a l . (1972), Echols and C u r r i e r (1973), Moody and Peters (1972). Koch (1973) reported t h a t butt j o i n t i n g d i d not s i g n i f i c a n t l y reduce stre n g t h provided laminae were t h i n and butt j o i n t s staggered. 2.2 Economic F e a s i b i l i t y The development around 1930 of high-temperature-curi n g phenolic r e s i n glues was a breakthrough i n adhesives technology because i t made p o s s i b l e cheap bonds more durable than the wood (Marra 1956). The high temperature requirement made these adhesives i n a p p l i c a b l e to laminated beams because of the i m p r a c t i c a l i t y of f o r c i n g heat i n t o any s u b s t a n t i a l depth i n wood. Production of beams one inch t h i c k and up, on a hot press may take 60 minutes or more to ensure complete p o l y m e r i z a t i o n of r e s i n (Wood 1963). Development of r a d i o frequency (RP) heating has reduced t h i s problem, but according to Chugg (1964) and Wood (1963), the system i s p r o h i b i t i v e l y c o s t l y and hence has not gained widespread acceptance. High i n i t i a l cost of RF equipment demands large scale operation t o ensure p r o f i t a b i l i t y 1 12 I (Winlund 1947). Other f a c t o r s of cost such as maintenance and requirement of high t e c h n i c a l s k i l l of operators were c i t e d by Arneson (1947) and the q u a l i t y of f i n i s h e d products, which was questionable as a r e s u l t of a r c i n g of some adhesives, was mentioned by Orth and Norton (1947). I n t r o d u c t i o n of co l d s e t t i n g r e s o r c i n o l glues i n the 1940's eased the problem of high temperature curing but r e s o r c i n o l glues were about f i v e times as c o s t l y as the phenolics (Marra 1956) and c u r r e n t l y are about s i x times as c o s t l y (Koch 1973). The amenability of r e s o r c i n o l to m o d i f i c a t i o n w i t h phenol-formaldehyde g i v i n g f a s t e r c u r i n g at low heat input has made these e x t e r i o r glues gain s u b s t a n t i a l p o p u l a r i t y i n the i n d u s t r y . Most of the work done on la m i n a t i n g t h i c k veneer has been w i t h r e s o r c i n o l or r e s o r c i n o l - m o d i f i e d phenol-formaldehyde (Murphey et a l . 1967, Koch 1967, Koch and Woodson 1968, Hann et a l . 1971, Schaff e r et a l . 1972, Moody and Peters 1972, Echols and C u r r i e r 1973, and Koch 1973). A l l , except Hann et al.(1971) and Schaffer et a l . (1972), Moody and Peters (1972), and Jok e r s t (1972) i n v o l v e d very long c o l d pressing times, thus adding t o the manufacturing cost due to t i e down of equipment and f a c t o r y space. At room temperature (70°F) phenol-resor-c i n o l formaldehyde w i l l cure i n 8 hours (Borden Chemicals 1970), at 180°F i n seven minutes and at 220°F i n three 4 minutes. P r i v a t e communication w i t h chemistry l a b o r a t o r y s t a f f of Borden Chemicals (Canada) L i m i t e d , Vancouver, 1973. 13 Marra (1956), i n embarking on research f o r developing the process f o r laminating 2 x 4*s from 1 x 4 -i n c h boards, set two t a r g e t s , t o ensure p r o f i t a b i l i t y . These were ( i ) ensuring usage of an e x t e r i o r or b o i l -proof adhesive and, ( i i ) development of a high-speed, low-cost g l u i n g operation which would maintain t o t a l g l u i n g cost at between $10 and $20/Mfbm. The l a t t e r excluded use of c o l d - s e t t i n g phenol or r e s o r c i n o l adhesives. In h i s study the eventual use of h o t - s e t t i n g phenol formalde-hyde glue reduced the glue cost from $12.50 to $2.50/Mfbm of 2 x 4*s. S c h a f f e r et a l . (1972 ) recorded $44.50/Mfbm f o r p h e n o l - r e s o r c i n o l adhesive cost f o r 6-ply Pres-Lam. Koch (1973) gave an estimate of $7.00/Mfbm of lumber a l l but one of the s i x g l u e l i n e s being of unmodified phenol-formaldehyde glue. Schaffer et a l . (1972 ) estimated the s e l l i n g p r i c e of Pres-Lam at between $150 and $200 and production cost at $126/Mfbm. Bohlen estimated LVL produc-t i o n cost to be $94.00/Mfbm while Koch (1973) gave h i s cost estimate as $136/Mfbm. While no d i r e c t comparison i s p o s s i b l e between these three cost estimates, i t could be assumed, on the b a s i s of glue consumption alone, t h a t i Bohlen's LVL would probably be the most economically favour-a b l e . 2.3 Technical F e a s i b i l i t y T e c h n ical f e a s i b i l i t y of Laminated Veneer Lumber hinges on the ^curing temperature of the glue to be used. 14 the wood species i n v o l v e d , the rat e at which they w i l l be penetrated by heat t o cure the c e n t r a l g l u e l i n e and t h e i r g l u a b i l i t y w i t h regard t o d e n s i t y , pH and e x t r a c t i v e content. These c o n d i t i o n s are f a i r l y common to a l l g l u i n g or l aminating processes and i n v o l v e wood surface prepara-t i o n and a p p l i c a t i o n of glue, heat and pressure. As w i t h most s o l i d s , even when wood i s properly planed, the surface i s s t i l l rough and e x h i b i t s demon-s t r a b l e topography at the microscopic l e v e l (Marian, Stumbo and Maxey 1958, Stumbo 1960, and Parker 1966). Surface roughness of r o t a r y cut veneer i s p a r t l y due t o d i f f e r e n c e s i n the e l a s t i c behaviour of springwood-summer-wood as w e l l as lathe c o n d i t i o n s at time of pee l i n g (Marian and Stumbo 1962, F e i h l 1960, and F e i h l and Godin, 1970). The peaks and troughs i n the surface do not g e n e r a l l y mesh but the peaks make intimate contact one w i t h another, while the troughs remain as vo i d s i n the j o i n t . Zisman (1963), Marian and Stumbo (1962), and Baier et a l . (1968), demonstrated t h a t under pressure and temperature, p l a s t i c and e l a s t i c deformations are induced at the a s p e r i t i e s . According to Marian and Stumbo (1962), the deformations depend on the v i s c o - e l a s t i c ( r h e o l o g i c a l ) p r o p e r t i e s of wood, extent of surface roughness, pressure, temperature and moisture content (Perkitney and Helinska 15 1961),5 other p h y s i c a l p r o p e r t i e s (Bauman and Marian 1961), q u a l i t y of veneers ( C u r r i e r I960)., c r y s t a l l i n i t y of wood (Murphey 1963), and presence, absence or type of glue (Curry 1957). Various workers or o r g a n i z a t i o n s have s p e c i f i e d acceptable ranges of pressing c o n d i t i o n s f o r v a r i o u s wood species and panel products. The American N a t i o n a l Standards (1973) s p e c i f i e s a pressure range of 150 to 250 p s i f o r glulam, the upper l i m i t being recommended f o r dense hardwoods and the lower l i m i t f o r softwoods. I t i s a l s o recommended that non-p l a n a r i t y of laminates be avoided i n order to f a c i l i t a t e c ontact. Shelton (1969) described the experience of the plywood i n d u s t r y . He r e c a l l e d that pressures used ranges from 100 to 300 p s i ( u s u a l l y 175 to 225 p s i ) and temperatures from 220°F to 350°F ( u s u a l l y 275°F to 3l5°F). Carruthers (1969) simulated the B r i t i s h hardwood plywood i n d u s t r y p r a c t i c e i n h i s study by employing pressures ranging from 150 to 300 p s i , depending on species and d e n s i t y , f o r veneer moisture contents ranging from two to 18 percent. U.S. Forest Products Laboratory, Madison and Gamble Brothers (1944) recommended average g l u i n g pressures of 100 to 300 p s i f o r Oak and 150 to 200 p s i f o r softwoods. Freeman (1959) used g l u i n g pressures of 150, 200 and 300 p s i , c o r r e l a t e d w i t h O r i g i n a l not seen. C i t e d from Palka (1964). 16 s p e c i f i c g r a v i t i e s of 0.36 to 0.45, 0.46 to 0.55 and 0.56 and above, r e s p e c t i v e l y . Lutz (1955) recommended 250 to 275 f o r h i c k o r y while Truax (1929) suggested pressures as high as 300 p s i e s p e c i a l l y f o r c o l d p r e s s i n g . In h i s study of f a c t o r s i n f l u e n c i n g strength p r o p e r t i e s of D o u g l a s - f i r plywood normal to the g l u e l i n e , Palka (1964) found t h a t : ( i ) pressure h i g h l y s i g n i f i c a n t l y a f f e c t e d both compression and t e n s i l e p r o p e r t i e s of r o t a r y peeled veneer, and only the former i n case of sawn veneer b l o c k s ; ( i i ) optimum r e s u l t s were obtained at 200 p s i g l u i n g pressure, c l o s e l y followed by 350 p s i ; ( i i i ) a pressure of 50 p s i was found to be inadequate. Redfern and Fawthrop (1945) reported the i n t e r - r e l a t i o n s h i p of pressure and moisture content of veneer i n D o u g l a s - f i r plywood hot-pressed w i t h a l i q u i d phenolic r e s i n glue. Cheo (1946)^ used three d i f f e r e n t g l u e s — p h e n o l i c f i l m , l i q u i d phenolic and s o y b e a n — i n a s i m i l a r study. Macdonald (1951) studied time, temperature, and pressure as major f a c t o r s l e a d i n g to compression of p l y -wood and o u t l i n e d the use of a p r e s s u r e - c o n t r o l device which could cut down compression from 9 percent to from 6 O r i g i n a l not seen. C i t e d from Olson and Blom-q u i s t (1953). 7,8 O r i g i n a l not seen, c i t e d from C u r r i e r ( i 9 6 0 ) . 17 3 to 7 percent. Curry (1957) studied the compression and r e s i n impregnation of plywood and found t h a t compression takes place i n bands adjacent to the g l u e l i n e s and increased w i t h number of p l i e s . He al s o observed t h a t because of a l t e r n a t e bands of weak and strong wood r e s u l t -ing from overcompression, the expected increase i n strength might not be r e a l i z e d . C u r r i e r (i960) demonstrated the ne c e s s i t y f o r pressure c o n t r o l when pressing D o u g l a s - f i r white pocket veneer. He concluded that normal hot-pressing schedules l e d to overcompression of the white pockets i n veneers while compression was minimized through gradual r e d u c t i o n a f t e r f u l l i n i t i a l pressure. The manufacture, f o r m u l a t i o n and c u r i n g of phenol-formaldehyde and some modified phenolic r e s i n adhesives were discussed by Parker and Taylor (1966). They'described the c uring as a c r o s s - l i n k i n g p o l y m e r i z a t i o n process which i s accomplished by a p p l i c a t i o n of heat and pressure. A temperature range of 250 - 300°F, maintained at clamp times which depend on c o n s t i t u t i o n of r e s i n and wood species, was given. Chow et a l . (1973), showed that acceptable wood f a i l u r e f o r e x t e r i o r phenolic resin-bonded plywood develop around 250°F. They analysed the data supplied by Canadian Forest Products L i m i t e d , and from the f i g u r e s produced f o r seven, f i v e and t h r e e - p l y plywoods, the CSA 80 percent wood f a i l u r e standard was a t t a i n e d at inner g l u e l i n e temperatures 240, 250 and 260°F r e s p e c t i v e l y . 18 The usual p r a c t i c e i s not t o completely cure the boards i n the press but to a t t a i n a s u f f i c i e n t measure of cure which w i l l hold the board together while c u r i n g completes during hot s t a c k i n g . J a r v i (1967) discussed the v a r i o u s l i m i t a t i o n s t o speed at which the temperature of the inner g l u e l i n e of D o u g l a s - f i r plywood can be r a i s e d . He stated t h a t the consensus i n i n d u s t r y i n d i c a t e s that inner g l u e l i n e should reach 220°F before pressure i s released since experience shows that temperature w i l l r i s e t o about 250°F during hot s t a c k i n g . Chow et a l . (1973) c i t e d some i n d u s t r y f i g u r e s of 180, 210, 220°F.and more but warned that t o avoid f a i l u r e the i n d u s t r y must ensure t h a t proper temperature i s a t t a i n e d during hot s t a c k i n g . Carruthers (1959) i n v e s t i g a t e d heat p e n e t r a t i o n i n hardwood plywood using p l a t e n temperatures not exceeding 100°C (212°F). He found there could be considerable v a r i a t i o n i n heat p e n e t r a t i o n over the e n t i r e panel surface and at the edges owing to v a r i a t i o n of thermal p r o p e r t i e s , moisture content and heat l o s s . For up to one inch panel t h i c k n e s s , heat l o s s could be compensated f o r by i n c r e a s i n g c a l c u l a t e d heating time by some f a c t o r . At pl a t e n temperatures above 100°C, h i s r e s u l t s apply only to the centre of large boards. He pointed out that t h e o r e t i c a l c a l c u l a t i o n of heating time cannot replace a c t u a l measurement. MacLean (1943) developed mathematical formulae f o r computing rate of temperature change i n wood panels heated between two p l a t e s of unequal 19 temperature. From computed data, he developed curves from which heating times could be read d i r e c t l y or by e x t r a p o l a t i o n . In a more recent paper, MacLean (1955) reported extensive work done on temperature change i n wood panels (plywood or s o l i d lumber boards) heated between platens maintained at the same temperature. He developed curves f o r panels heated between platens at; 225 to 325°F. Hi s work included examples of v a r i o u s panel s i z e s and p r e s s i n g c o n d i t i o n s . Within the l i m i t s of h i s experiments, heating times are undesirably long f o r panels t h i c k e r than one i n c h . The r e q u i r e d r a t e of gluespread i s c l o s e l y l i n k e d w i t h adherent surface c o n d i t i o n and wood species and i t u l t i m a t e l y a f f e c t s press time. F i s c h e r and Bensend (1969) reported that r a t e of gluespread e x h i b i t e d a l i n e a r response f o r shear and a p a r a b o l i c response f o r wood f a i l u r e v alues. The shear obtained i n the b o i l t e s t increased throughout the e n t i r e gluespread range of 60 to 100 pounds per thousand square feet of double g l u e l i n e (60 to 100 lb/MDGL) t e s t e d . The authors pointed out that maximum shear and wood f a i l u r e values occurred at 90 lb/MDGL i n the dry and vacuum/pressure t e s t , thus suggesting that b o i l t e s t s masked undercure at higher than 90 lb/MDGL. Other disadvantages of high r a t e of gluespread were given as excessive squeeze-out and steam-blows. C o c k e r e l l and Bruce (1946) and Bergin (1969) reported th a t strength of a l l adhesives decrease i n v a r y i n g degrees, w i t h an increase i n g l u e l i n e t h i c k n e s s . N orthcott et a l . 20 (1959) reported t h a t large amounts of water introduced i n t o the glueline-wood complex v i a high gluespreads i n t e r f e r e w i t h normal phenolic r e s i n condensation r e a c t i o n . Cockerell and Bruce (1946) a t t r i b u t e d the lower bond strength mainly to e c c e n t r i c i t y of t e s t specimens due t o d i f f e r e n c e i n g l u e l i n e t h i c k n e s s but F i s c h e r and Bensend (1969) suggested the strength d e c l i n e i s due t o i n t e r n a l , s t r e s s e s developed w i t h i n g l u e l i n e s or i n t e r r u p t i o n of the phenolic r e s i n p o l y m e r i z a t i o n process as described by Northcott et a l . (1959). B e r g i n ^ i n an unpublished paper described ways to c o n t r o l gluespread. He a l s o showed photomicrographs of normal, starved, glazed and crazed j o i n t s , the second and l a s t r e s u l t i n g from inadequate gluespread. Using veneers peeled under l a b o r a t o r y c o n d i t i o n s , Bohlen (1972a) found that the standard plywood gluespread of 30 lb/MSGL was adequate f o r D o u g l a s - f i r LVL. In a p r i v a t e d i s c u s s i o n w i t h B e r g s e n , 1 0 i t was found that veneers produced i n i n d u s t r y were u s u a l l y rough and, i n some in s t a n c e s , gluespreads as high as 42.5 lb/MSGL were used to counter the roughness. 2.4 G l u a b i l i t y As part of h i s MF t h e s i s at the U n i v e r s i t y of B.C., 7Glue J o i n t F a i l u r e s and t h e i r Causes, by E. G. B e r g i n , Forest Products L a b o r a t o r i e s D i v i s i o n , Department of Resources and Development, Ottawa. " ^ P r o p r i e t o r of Truboard, the p r i v a t e company t h a t produced D o u g l a s - f i r LVL i n Vancouver i n 1972-73. 21 Chunsi (1973) reviewed the l i t e r a t u r e on g l u a b i l i t y of t r o p i c a l hardwoods w i t h reference to t h e i r physico-chemical c h a r a c t e r i s t i c s and the i n f l u e n c e of v a r i o u s l a m i n a t i n g g l u e s . He examined s i x Burmese hardwoods and found that species w i t h medium to high d e n s i t y had high e x t r a c t i v e contents but showed no d i r e c t r e l a t i o n s h i p between the amount of e x t r a c t i v e s and g l u a b i l i t y . He showed, b a r r i n g the i n f l u e n c e of s p e c i f i c g r a v i t y , a trend of increase i n glue j o i n t strength w i t h i n c r e a s i n g pH. Freeman (1959) reported that s p e c i f i c g r a v i t y i s the dominant f a c t o r i n the low d e n s i t y r e g i o n , when urea r e s i n glue was used, and throughout the e n t i r e d e n s i t y range te s t e d (0.40 to 1.16) w i t h r e s o r c i n o l - p h e n o l glue. He r e l a t e d the l a t t e r behaviour to wood/resorcinol j o i n t strength which i s g e n e r a l l y l i m i t e d by s o l i d wood shear strength. This i s a l s o true of high temperature curing phenol--formaldehyde glue-wood j o i n t s (Marra 1956). Cartensen (1961) a t t r i b u t e d the development of a broad range of adhesives t h a t w i l l bond D o u g l a s - f i r e x c e l l e n t l y t o the f a c t that D o u g l a s - f i r has been a favoured species and hence a l o t of research has been done on i t s u t i l i z a t i o n f o r plywood and lumber. Using D o u g l a s - f i r as a standard, he showed the v a r i o u s m o d i f i c a t i o n s of glue a p p l i c a t i o n and bonding process that would ensure develop-ment of the same l e v e l of bond strength i n v a r i o u s softwoods and hardwoods as i s produced w i t h D o u g l a s - f i r under standard g l u i n g c o n d i t i o n s . He concluded t h a t , provided c e r t a i n 22 s p e c i e s c h a r a c t e r i s t i c s such as a c c u m u l a t i o n of r e s i n o u s m a t e r i a l s on veneer s u r f a c e and p o r o s i t y due t o low d e n s i t y are t a k e n c a r e o f , and veneers are p r o p e r l y d r i e d , a l l the s p e c i e s c o n s i d e r e d i n h i s st u d y c o u l d be g l u e d e q u a l l y w e l l w i t h p r a c t i c a l l y any c o n v e n t i o n a l plywood a d h e s i v e . He a l s o d i s c u s s e d the p o t e n t i a l of t h e hardwood plywood i n d u s t r y . The g l u a b i l i t y of 14 hardwoods and s i x softwoods of E a s t e r n Canada were r e p o r t e d by B e r g i n (1953, 1964). He used two s y n t h e t i c and two n a t u r a l g l u e s i n the s t u d y , and h i s c o n c l u s i o n agreed w i t h C a r t e n s e n (1961) t h a t when g l u i n g c o n d i t i o n s a re p r o p e r l y c o n t r o l l e d , a l l the 20 s p e c i e s i n h i s st u d y c o u l d produce e x c e l l e n t bond s t r e n g t h . He c l a s s i f i e d the 20 s p e c i e s i n t o f o u r c a t e g o r i e s of g l u a b i l i t y based on wood f a i l u r e . He a l s o showed t h a t g l u a b i l i t y of any one s p e c i e s may d i f f e r from t h a t of o t h e r s p e c i e s w i t h i n the same d e n s i t y range. E i c k n e r (1942) i n v e s t i g a t e d 11 hardwoods and fo u r ' softwoods f o r g l u a b i l i t y w i t h c a s e i n and c o l d s e t t i n g u r e a r e s i n g l u e s . He found no c o n s i s t e n t d i f f e r e n c e between heartwood and sapwood, e x c e p t i n H i c k o r y ( C a r y a s p . ) . He c o n c l u d e d t h a t the 15 s p e c i e s c o u l d be bonded t o produce j o i n t s as s t r o n g i n shear as t h e wood i t s e l f though, w i t h c a s e i n g l u e , shear s t r e n g t h d e c l i n e d w i t h i n c r e a s i n g wood d e n s i t y . Bruce e t a l . (1944), i n an u n p u b l i s h e d paper, r e p o r t e d some s t r e n g t h d a t a on b i r c h plywood bonded w i t h low tem p e r a t u r e c u r i n g r e s i n g l u e s . •. .1 23 They also discussed r e s i n glue behaviour as they vary i n t h e i r r a t e of cure between wood species. He observed t h a t r e s o r c i n o l glues seemed to have a s i m i l a r c u r i n g r a t e i n b i r c h , spruce and mahogany, while they cure more slowly i n D o u g l a s - f i r , white oak, and p o s s i b l y sweetgum. The trend f o r melamine glues was a s i m i l a r r a t e on b i r c h and sweetgum but a more r a p i d r a t e on D o u g l a s - f i r , white oak, mahogany and spruce. With phenolic r e s i n glues, c u r i n g r a t e was said t o be s i m i l a r i n b i r c h , spruce and mahogany, slower on D o u g l a s - f i r , and slower s t i l l on white oak and sweetgum. Most published papers d e a l i n g w i t h LVL production are l i m i t e d t o one or a few aspects of the process. The work at the Western Forest Products Laboratory d e a l t 1 s p e c i f i c a l l y w i t h D o u g l a s - f i r . While i t demonstrated the p o t e n t i a l f o r D o u g l a s - f i r , i t d i d not q u a n t i f y the bond q u a l i t y at the step j o i n t s and the s u i t a b i l i t y of other species was not discussed. Pres-Lam s t r u c t u r a l m a t e r i a l was s p e c i f i c a l l y developed f o r southern pines. Very l i m i t e d work has been reported on hardwoods and only the work of Hann et a l . (1971) gave the f e a s i b i l i t y of laminating poor q u a l i t y red oak f o r n o n s t r u c t u r a l p a l l e t deckboards. Most of the l i t e r a t u r e reported on g l u e l i n e temperature r i s e d e a l t s p e c i f i c a l l y w i t h plywood. This study w i l l t h e r e f o r e supply some of the much needed in f o r m a t i o n on la m i n a t i n g ^ - i n c h -t h i c k hardwood veneers, and s p e c i f i c a l l y on the s u i t a b i l i t y 24 of the l a m i n a t i n g process described by Bohlen (1972a) f o r the species used i n t h i s study. 2.5 The Laminating Process Bohlen (1972a) chose -^-inch p l i e s through a c o n s i d e r a t i o n of the t h i c k e s t veneer p o s s i b l e t o minimize the number of g l u e l i n e s while s t i l l maintaining produc-t i v i t y r e l a t e d to l a t h e speed and veneer drying time. He c l i p p e d the veneers i n t o 26 by 48-inch dimensions f o r ease of handling. Veneers were l a i d up w i t h " t i g h t " 1 1 side of veneers towards the outside of the LVL. Balanced c o n s t r u c t i o n was maintained by arranging the veneers "loose" t o " t i g h t " side except the c e n t r a l g l u e l i n e which was "loose" t o "loose." Using the f i n d i n g of F r i t z ( 1 9 6 9 ) 1 2 t h a t no i n t e r -a c t i o n e x i s t s between s t r e s s concentrations at butt j o i n t s of adjacent lamina t i o n s once such j o i n t s are f u r t h e r apart than 16 times the t h i c k n e s s of laminations, Bohlen decided that step j o i n t s should not be l e s s than four inches a p a r t . For a safety measure, he chose s i x inches f o r D o u g l a s - f i r LVL i n h i s study. He used the normal production mix of phenol-formal-dehyde plywood glue, a gluespread of 30 lb/MSGL and a press 1 1 " T i g h t " side of veneer i s that on which the pressure bar r e s t e d during peeling and "loose" side i s the opposite s u r f a c e . 12 O r i g i n a l not seen. C i t e d from Bohlen (1972a). 25 time of 20 minutes at a pla t e n temperature of 300°F. The layup consisted of arranging the veneers i n " s t a i r " f a s h i o n , w i t h each step being s i x inches apart. The forward indexing was arranged such that the edge of the topmost l a m i n a t i o n c o i n c i d e d w i t h the edge of the upper p l a t e n . In t h i s case, f i v e p l i e s were s t i c k i n g out of the press and the lower face of four of them had been gluespread. P r i o r to press opening, the next s e r i e s of gluespread veneers were placed t i g h t l y against the steps s t i c k i n g out of press. In a l l cases the bottom p l y was not gluespread. In the next press c y c l e , the assembly was indexed forward by 48 inches thus c r e a t i n g a new s e r i e s of steps s t i c k i n g out of the press. The l a s t press c y c l e i n v o l v e d c l o s i n g up the steps with veneers cut t o s i z e so that no new steps were created. 26 3.0 MATERIALS AND METHODS 3.1 Veneer The four wood species used i n t h i s study are: ( i ) Broadleaf maple - peeled at the WFPL ( i i ) Sugar maple - " " " EFPL ( i i i ) Black cottonwood- " " " WFPL ( i v ) White spruce - " " " WFPL 3.1.1 Broadleaf Maple The broadleaf maple (BMP) veneers were i n assorted s i z e s from s i x t o 15 inches wide by 20 t o 48 inches long. They were s e l e c t e d from the veneers peeled from #3 to c u l l grade b o l t s . ^ The q u a l i t i e s of dry veneers are tabulated below: Items of Veneer Q u a l i t y Mean Standard D e v i a t i o n Range Veneer t h i c k n e s s ( i n . ) Veneer roughness ( i n . ) Depth of l a t h e check {%) Mean moisture content {%) 0.282 0.035 85 6 0.6 0.016 0.197-0.304 15 0.010-0.045 1.9-8.4 20-99 3.1.2 Sugar Maple The sugar maple (SMP) veneers were peeled to nominal 13 The B.C. f i r log grading r u l e s were ap p l i e d i n the absence of any grading r u l e f o r broadleaf maple. 27 ^ - i n c h by the s t a f f of the Eastern Forest Products Laboratory, Ottawa.! 4 The pe e l i n g parameters are given i n Appendix l ( a ) . The q u a l i t i e s of green veneers are given i n Appendices l ( a ) and l ( b ) , f o r the p r e l i m i n a r y and f i n a l p e e l i n g s , r e s p e c t i v e l y . The drying schedule given i n Appendix l ( c ) , was used t o dry the green veneers, at the EFPL, from approximately 90 t o two percent moisture content. The veneers" were wrapped i n polyethylene sheets p r i o r to shipment, and a l l the p a r c e l s were i n t a c t on d e l i v e r y . Hence t r a n s i t c o n d i t i o n s d i d not s e r i o u s l y a f f e c t the moisture content of the veneers. 3.1.3 Black Cottonwood Four 55-inch long black cottonwood (BCW) b o l t s were obtained from one t r e e growing at the U n i v e r s i t y of B r i t i s h Columbia Research F o r e s t . The b o l t s ranged from 14 to 17-inch l a r g e end diameter and 13 t o 16-inch small end diameter. The b o l t s were transported t o the WFPL (three days a f t e r the t r e e was f e l l e d . They were kept wet w i t h water s p r i n k l e r s f o r another four days a f t e r which they were manually debarked p r i o r t o p e e l i n g . E a r l i e r p e e l i n g studies by F e i h l and Godin (1966) had shown th a t optimum c u t t i n g temperature f o r Aspen poplar 14 F e i l and Godin (1973), Forest Products Laboratory departmental correspondence f i l e 361-3-1-1, and Telex (see Appendix I ( a ) . ' i 28 i s s l i g h t l y above f r e e z i n g point and that good veneer can be cut at room temperature (70°F). The BCW b o l t s were t h e r e f o r e peeled col d , using the p e e l i n g parameters given i n Appendix I I . A l l b o l t s peeled e a s i l y t o a f i v e - i n c h core. S i x t y - f o u r f u l l width (25-inch) sheets; 22 narrows (seven t o f i f t e e n inches wide); and s i x " f i s h t a i l s " ( f i v e t o ten inches wide by 20 t o 39 inches long) were produced. The veneers were graded according to CSA standard 0153-1963 which covers "poplars" growing i n Canada. The frequency of the d i f f e r e n t grades i n the black cottonwood veneers produced i s presented i n Table 1. To o b t a i n the green moisture content of the veneers two f o u r - i n c h s t r i p s , 54 inches l o n g , were randomly c l i p p e d , one from sapwood and the other from heartwood, of each b o l t . The s t r i p s were wrapped up i n polyethylene p l a s t i c sheets f o r about 30 minutes to minimize moisture l o s s while the green chain was being c l e a r e d . Each s t r i p was then sawn i n t o three 18-inch p i e c e s , weighed, and oven-d r i e d . The average green moisture content of the wood zones and average f o r a l l b o l t s are presented i n Table 2. Poplars g e n e r a l l y have a high tendency t o r e t a i n pockets of high moisture content i n d r i e d m a t e r i a l (Farmer 1972). To e l i m i n a t e t h i s , the author decided t o dry the veneers as close t o oven-dry weight as p o s s i b l e . The Forest Products Laboratory four f e e t by s i x f e e t d r y i n g 29 k i l n , which has a continuous weighing device, was used. The veneers were d r i e d i n two f u l l charges and a t h i r d which was 33 percent BCW and 67 percent a i r - d r i e d Douglas-f i r veneers which were used t o f i l l ' u p t h e . k i l n so as to avoid the problem of short c i r c u i t i n g and improper a i r d i s t r i -b u t i o n that would r e s u l t from operating the k i l n below c a p a c i t y . H a l f - i n c h - t h i c k s t i c k e r s were used between veneers and the top veneers were weighted t o l i m i t movement and edge waviness during d r y i n g . The s i x " f i s h t a i l s " were sawn t o 20-inch lengths and were located i n p a i r s at three l e v e l s i n the f i r s t charge and two "narrows" were sawn i n t o s i x 18-inch pieces and lo c a t e d i n the same l e v e l s i n the second charge. These were used t o check the moisture contents of each charge by oven drying i n a smaller oven. The k i l n schedule used f o r the three charges i s shown i n Appendix I I I . Since each k i l n charge was t o be d r i e d u n t i l the weight was constant, a mild d r y i n g schedule of 220°F i was used. A l l k i l n charges were d r i e d t o constant weight but samples showed the average moisture content t o be from three t o f i v e percent. A l l f u l l s i z e veneers were squared t o 25 by 53 inches and the narrows were squared t o 52-inch lengths by as c l o s e t o t h e i r o r i g i n a l widths as p o s s i b l e . A l l veneers were wrapped up i n polythene sheets p r i o r t o the LVL study. 30 3.1.4 White Spruce F i f t e e n pieces of 20 .by 52-inch ^ - i n c h white spruce (WSP) veneers, produced f o r p e e l i n g studies by the veneer p e e l i n g s e c t i o n of the WFPL, were used i n a l i m i t e d aspect of t h i s study. The veneers had been s t i c k e r e d i n the l a b o r a t o r y f o r about two months t o a i r dry. Further drying the spruce veneers was not attempted because the veneers had a t t a i n e d an EMC of about seven percent, and f u r t h e r d r y i n g could r e s u l t i n over drying w i t h consequent surface i n a c t i v a t i o n . I t has been reported that WSP i s sus c e p t i b l e t o surface i n a c t i v a t i o n (Chow 1969). To avoid veneers w i t h s e r i o u s surface contamination, the upper and lower f i v e pieces of veneer i n the stack were avoided, and the veneers were removed from the stacks j u s t p r i o r t o the grading and LVL manufacture. From the forego i n g , i t i s evident t h a t the manu-f a c t u r e and dr y i n g h i s t o r y of the veneers of d i f f e r e n t species used i n t h i s study d i f f e r . Comparison w i l l be made only where these d i f f e r e n c e s do not make such comparisons meaningless. 3.2 Glues U t i l i z a t i o n of low grade wood m a t e r i a l i s the most a t t r a c t i v e aspect of LVL. Since such poor q u a l i t y m a t e r i a l s are often d i f f i c u l t t o glue owing t o d e f e c t s such as c r o s s -g r a i n , end g r a i n at knots and accumulating of r e s i n s and other physico-chemical c h a r a c t e r i s t i c s , i t i s of utmost 31 importance that adequate bonding be ensured. Resin glues capable of producing e x t e r i o r bonds were, t h e r e f o r e , considered f o r t h i s study. Three glues were t r i e d i r i v a r i o u s aspects of t h i s study. They inc l u d e Reichhold Chemicals' phenolic r e s i n s IB-337 Plyophen and IB-334 Plyophen, and Borden Chemicals' Cascophen (2600-CR 40), and are described below. 3.2.1 IB-337 Plyophen Reichhold Chemicals' IB-337 Plyophen ( h e r e a f t e r c a l l e d PF IB-337) phenolic r e s i n produces high q u a l i t y e x t e r i o r adhesive bonds f o r the plywood i n d u s t r y . I t was used s u c c e s s f u l l y i n the development of D o u g l a s - f i r LVL at the Western Forest Products Laboratory. I t i s character-i z e d by moderate to good t o l e r a n c e t o long assembly times, a feature used to advantage i n producing continuous L y L , and f a s t r a t e s of cure. The glue was supplied ready-mixed by the manufactur-e r . The glue mix, and mixing sequence f o r a f i v e - g a l l o n bucket of glue are given i n Appendix I Y ( a ) . V i s c o s i t y of glue measured w i t h a B r o o k f i e l d LVF Viscosimeter on No. 3 spindle (at glue lab.) was: 4,000 cps at 6 rpm, and 1,720 cps at 60 rpm. On No. SC4-34/14 spindle (at WFPL) v i s c o s i t y was: 4,600 cps at 6 rpm, and ! 3,590 cps at 12 rpm. 32 The d i f f e r e n c e was due to i n b u i l t d i f f e r e n c e s i n v i s c o s i m e t e r s r a t h e r than change i n degree of polymeriza-t i o n of the glue because f u r t h e r t e s t s one week l a t e r d i d not show any change i n v i s c o s i t y or DP. The mixed glue was stored i n . a c o l d room at 34°F p r i o r to use. The pH was 12.6. 3.2.2 IB-334 Plyophen This r e s i n i s a l s o water soluble and produces high q u a l i t y e x t e r i o r plywood bonds. The manufacturer claims t h a t , when used according to t h e i r i n s t r u c t i o n s , IB-334 (PF IB-334 h e r e a f t e r ) " i s abnormally t o l e r a n t t o c o n d i t i o n s of long assembly times and high ambient and stock tempera-t u r e s encountered . . . during the summer months." This glue was explored f o r p o s s i b l e improvement over the bond produced w i t h PF IB-337. The glue was a l s o supplied ready-mixed and the mix and mixing sequence f o r a f i v e g a l l o n p a i l are shown i n Appendix I V ( b ) . V i s c o s i t y measured on d e l i v e r y at the WFPL l a b o r a -t o r y was 7000 cps at 6 rpm using #SC4-34/l3 s p i n d l e . The pH was a l s o 12.6. The v i s c o s i t y a l s o remained unchanged a f t e r three weeks storage i n a 34°F c o l d room. 3.2.3 Cascophen 904-003-Catalyst 400-040 (2600-CR40) Cascophen 904-003-Catalyst 400-040 i s a modified p h e n o l - r e s o r c i n o l r e s i n glue (MPRG) f o r use i n wood laminat-33 ing and general assembly g l u i n g . According t o the manufacturer, i t g i v e s a completely waterproof e x t e r i o r adhesive bond and passes the t e s t s r e q uired by the Canadian Standards A s s o c i a t i o n s p e c i f i c a t i o n f o r Phenol and R e s o r c i n o l r e s i n adhesives f o r wood, CSA 0112.7-1960 (Cl a s s 1, Type I and I I and C l a s s 2 Type I I ) . This more.expensive glue was used t o determine the f u l l p o t e n t i a l of the bond stren g t h that could be produced w i t h r o t a r y - p e e l e d ^ - i n c h veneers. 3.3 Experimental Procedure 3.3.1 Aspects of the Study The experiments were done i n four main stages: determination of adequate g l u i n g c o n d i t i o n s f o r ( l ) broad-l e a f maple, and (2) f o r sugar maple and b l a c k cottonwood veneers; (3) i n v e s t i g a t i n g the q u a l i t y of bonds developed i n the step j o i n t s of boards produced by s i m u l a t i n g the l a s t step i n Bohlen 1s continuous LVL manufacturing process, and (4) the p h e n o l - r e s o r c i n o l bond q u a l i t y t e s t . The continuous LVL boards were manufactured from b l a c k c o t t o n -wood, sugar maple and white spruce veneers. 3.3.2 Experimental Design 3.3.2.1 Small panel t e s t s The design of the experiments f o r determining press 15 schedules, using small panels, i s presented i n Table 3. 15 S i z e of panels are given under panel c o n s t r u c t i o n and c o n d i t i o n i n g . : 34 In a l l cases, i t was assumed th a t the f a c t o r s t e s t e d were r e s p o n s i b l e f o r the v a r i a t i o n i n the streng t h and r e l a t e d p r o p e r t i e s . This assumption was made on the b a s i s that other g l u i n g c o n d i t i o n s were held r e l a t i v e l y constant f o r a l l panels. The general model f o r a two f a c t o r a n a l y s i s of variance (ANOVA) w i t h i n t e r a c t i o n i s : Y i j k » /f +7i + £ j + W Hj •+ E i J k where TT and ^ are the two f a c t o r s , ( 1 ^ ) i j , the i n t e r -a c t i o n term and E i j k the e r r o r term. The s t a t i s t i c a l assumptions are: E i j k ^ N1D (0,,c£) i = 1 , k j = 1, - n i = 0 1=1 n. 2LGz = 0 3=1 K i = l j = l Only when the i n t e r a c t i o n term i s not s i g n i f i c a n t can Duncan's M u l t i p l e Range Test be c a r r i e d out. Whenever the i n t e r a c t i o n terms were s i g n i f i c a n t , the means f o r the v a r i o u s treatment combinations only were d i s c u s s e d . 35 The f a c t o r names and l e v e l s are presented i n Table 4. I n d i v i d u a l f a c t o r s are f u r t h e r discussed under the subheading Testing Procedure (3.3.5). Besides the ANOVA and Duncan's M u l t i p l e Range Test (DMRT) where a p p l i c a b l e , mean of observations f o r i n d i v i d u a l treatment combinations would be discussed., 3.3.2.2. Continuous LVL t e s t s These were designed t o t e s t s u i t a b i l i t y of the continuous process described by Bohlen. Mean values of the v a r i a b l e s , would be evaluated according t o American N a t i o n a l Standards s p e c i f i c a t i o n on glued laminated timber: Voluntary Product Standard P.S. 56 - 73. Standard d e v i a t i o n and c o e f f i c i e n t of v a r i a t i o n of the v a r i a b l e s would a l s o be discussed. The q u a l i t y response t e s t was designed t o show g r a p h i c a l l y the q u a l i t y of the c e n t r a l g l u e l i n e along the whole length of the continuous LVL. The graphs would show the t r a n s i t i o n between the s e c t i o n s . Delamination t e s t s would show the q u a l i t y of a l l g l u e l i n e s according to CSA 0177 - 1965. Besides the average delamination, performance of each board along i t s whole length would a l s o be discussed. .36 , 03.3.3 Panel C o n s t r u c t i o n and C o n d i t i o n i n g 3.3.3.1 Veneers f o r small panels The broadleaf maple veneers were very poor (see s e c t i o n 3.1.1). However, those selec t e d f o r panel c o n s t r u c t i o n were f r e e of knots l a r g e r than ^ - i n c h across the g r a i n , excessive g r a i n d e v i a t i o n , knot holes and other unsound d e f e c t s . Veneers were not planed but those showing observable t h i c k n e s s v a r i a t i o n were excluded. C l u s t e r knots and i s o l a t e d b i r d ' s eye were permitted. C h a r a c t e r i s t i c s of sugar maple and bl a c k cottonwood veneers, f o r small panels, are presented i n the f i r s t two rows of Table 5. The f i g u r e s are mean values c a l c u l a t e d from sample measurements. The measurements were taken on i four by f o u r - i n c h specimens cut from f u l l s i z e veneers (Figure 3 ) . Test-weight/ (M) and oven-dry weight (Mj;) of each specimen were taken and moisture content (MC) was c a l c u l a t e d from the equation: MC {%) = M " M l x 100 The percent depth of lat h e check and roughness (Northcott and Walser, 196o), were estimated.. Length and breadth of each specimen were measured w i t h d i a l c a l i p e r s c a l i b r a t e d t o 0.001 i n c h . Thickness was measured w i t h a pressure operated veneer thickness measurer developed at the WFPL, Vancouver. Myronuk (1972) described the semi-automatic model of the veneer t h i c k n e s s measuring system. S p e c i f i c g r a v i t y of each specimen was c a l c u l a t e d using test-weight and test-volume. 37 3.3.3.2 Gluing of small panels In a l l cases, s i x veneers were assembled w i t h t h e i r loose side toward the i n s i d e of the assembly. Glue was brushed on t o the lower surface of each of the f i v e upper p l i e s . Gluespread, based on lb/MSGL, was predeter-mined and the amount to be deposited on each of the f i v e p l i e s was kept constant by weighing. The small panels constructed f o r the v a r i o u s t e s t s are presented by number, i n Figure 4. P r e s s i n g c o n d i t i o n s other than those being t e s t e d are presented i n column 7 of the same f i g u r e . Broadleaf maple panels were 12 by 12 inches while those of black cottonwood and sugar maple were 12 by ei g h t inches. A l l panels were conditioned t o l a b o r a t o r y c o n d i t i o n s f o r seven days p r i o r t o machining. In a l l cases, temperatures of c e n t r a l and outer glue-l i n e s were taken. Copper-constantan thermocouples from a two-channel potentiometer recorder were used. When the c e n t r a l g l u e l i n e temperatures s p e c i f i e d i n the design were at t a i n e d the press was immediately opened. Further r i s e i n temperature was not recorded. The panels were hot-stacked f o r 24 hours before they were s t i c k e r e d f o r the l a s t s i x days of c o n d i t i o n i n g . The c o n t r o l panels f o r temperature measurement were not glued. The t e s t f o r e f f e c t of double-pressing was designed t o simulate the.condition i n which some pa r t s of LVL are pressed 38 once and others twice. I t takes approximately 20 minutes to r a i s e CGLT of assembled s i x - p l y sugar maple LVL to 240°F, and about three minutes t o l a y up gluespread veneers and index the assembly forward i n t o the press. The p o r t i o n pressed twice was simulated by pressing during two 20 minute press c y c l e s w i t h a three minute i n t e r v a l between press cycles,. Sugar maple and bl a c k cottonwood veneers laminated w i t h MPRG were conditioned i n the 12 percent e q u i l i b r i u m moisture content (EMC) chamber f o r three months. The veneers.attained an average MC of 8.4 and 12.7 percent, r e s p e c t i v e l y . Spreads below 37.5 lb/MSGL were d i f f i c u l t t o brush on to sugar maple veneers and even 37.5 lb/MSGL spread was d i f f i c u l t t o brush on to black cottonwood, owing t o the low v i s c o s i t y of the glue. The glue r e q u i r e s a minimum clamp time of seven minutes w i t h a CGLT of 180°F, or three minutes at 220°F. Because the CGLT continued t o r i s e a f t e r a t t a i n i n g 180°F, the boards were clamped f o r f i v e more minutes a f t e r t h i s CGLT was a t t a i n e d . T o t a l clamp time was 15 minutes. 3.3.3.3, Quantity and c h a r a c t e r i s t i c s of veneers used f o r the continuous LVL production Two f u l l lengths of veneer were used t o simulate the l a s t two press c y c l e s i n the continuous LVL production process. This means that 12 veneer sheets per board were used. F u l l lengths of BCW, SMP and WSP veneers were 52, 42, 39 and 50 inches, r e s p e c t i v e l y . Samples of 4-inch by 4-inch t e s t specimens were used t o measure veneer c h a r a c t e r i s t i c s which were determined as described f o r small panels. Specimens were cut as shown i n f i g u r e 5 and the mean veneer c h a r a c t e r i s t i c s are presented i n Table 5. 3.3.3.4 Glui n g of continuous LVL Panels were constructed i n two batches. The f i r s t batch c o n s i s t e d of one panel each of sugar maple, black cottonwood and white spruce LVL glued w i t h PF IB-337. The second batch c o n s i s t e d of one panel each of black c o t t o n -wood and sugar maple LVL and both were laminated with' PF IB-334. The continuous boards were 16 inches wide, and t h e i r lengths were determined by the o r i g i n a l l e n g t h of veneers ( f i g u r e s 5 and 6). Veneers f o r the s t a r t e r board were cut as shown i n f i g u r e 7. In order to avoid end crushing of the s t a r t e r board, a mid-segment c o n s i s t i n g of veneers of equal lengths was introduced i n t o the assembly such that the edge of the topmost veneer c o i n c i d e d w i t h the edge of the upper p l a t e n . Six steps t h e r e f o r e stuck out of the platens as shown i n f i g u r e s 1 and 2. At the end of the f i r s t press c y c l e , the f i v e steps were closed up w i t h veneers already cut t o s i z e and spread w i t h glue. The board was then indexed forward i n t o the press w i t h the end of the topmost p l y c o i n c i d i n g w i t h the edge of the p l a t e n as shown by the end board i n f i g u r e 3. 40 In the continuous board manufacture, a mechanical gluespreader w i t h rubber r o l l s was used t o apply glue to veneers. Proper contact of butt j o i n t s was ensured and the assembly was indexed i n t o the press manually. P l a t e n pressures used were 275 p s i f o r sugar maple, and 100 p s i f o r black cottonwood and white spruce. The press c y c l e f o r sugar maple and white spruce LVL was determined by the time f o r CGLT to reach 240°F. For black cottonwood LVL, the press c y c l e was f i x e d at 22 minutes. A longer press c y c l e was considered undesirable i n terms of production economics. 3.3.4 Specimen P r e p a r a t i o n 3.3.4.1 Shear b l o c k s from small panels Twenty block shear specimens were cut from each small panel of broadleaf maple LVL except f o r tha t used f o r adequate gluespread t e s t at 42.5 lb/MSGL from which, owing to h i g h l y d e f e c t i v e p o r t i o n s of one of the c e n t r a l p l y s , only ten shear blocks were obtained. Blocks were cut according to CSA 0177-1965. While t e s t i n g the c y c l i c (vacuum/ pressure) soak (CVPS) specimens, i t was observed that specimens swelled t a n g e n t i a l l y and some exceeded the width of the shearing head of the machine. For t h i s reason block shear specimens from one of the sugar maple panels were reduced i n width to approximately 1.9 i n . from 2 i n . - A few specimens s t i l l swelled i n excess of the width of the shearing head. Subsequent specimens were made 1.5 i n . wide. Sample size f o r the small panel t e s t s are shown i n Table 6. 41 3.3.4.2 Shear b l o c k s from continuous LVL boards The mid-segment i n the continuous boards were 42, 32, and 34 inches, f o r sugar maple, black cottonwood and white spruce, r e s p e c t i v e l y . A 24-inch segment of these, adjacent to the end-board j o i n t s , was pressed t w i c e . Therefore the remaining 18, 8 and 10-inch segments-^ were pressed only once (see f i g u r e 1, and the l a s t two segments of f i g u r e 3 f o r p l a t e n overlap, i . e . p o r t i o n pressed twice C5). Each continuous board was d i v i d e d i n t o s e c t i o n s : 1, pressed only once (the l a s t four inches of the topmost p l y of the s t a r t e r -board i n c l u s i v e ) ; 2, pressed twice (24 inches i n a l l cases); and 3, pressed once (the end board which was 30 inches i n a l l c a ses). Four 1.5-inch and four 2-inch s t r i p s were sawn from each board f o r block shear and delamination specimens, r e s p e c t i v e l y . Two 1.5-inch s t r i p s were randomly selec t e d f o r each of dry and CVPS t e s t s r e s p e c t i v e l y , two 2-inch s t r i p s f o r delamination t e s t ; and only i n case of PF IB-334 bonded LVL boards, the l a s t two were used f o r b o i l t e s t . In order to t e s t the bond q u a l i t y of the whole s t r i p , two-inch long block shear specimens were cut and coded c o n s e c u t i v e l y from the l a s t four inches of the top p l y of the 15 These lengths were estimated, using the topmost p l i e s only. 42 sta r t e r , board. In some i n s t a n c e s , the l a s t block of s e c t i o n 1 and/or s e c t i o n 2 was shorter than two inches. Because specimen length has s i g n i f i c a n t e f f e c t on shear strength ( S t r i c k l e r 1968), such substandard blocks were d i s c a r d e d . But f o r the width of 1.5 i n . , a l l b lock shear specimens were a l s o cut according t o CSA 0177-1965. Delamination and b o i l t e s t specimens were c u t ' i n t o two-inch cubes and were coded e x a c t l y as f o r b l o c k shear specimens. Subsize specimens were discarded. 3.3.5 Testing Procedure 3.3.5.1 Dry shear t e s t Test specimens were conditioned i n the l a b o r a t o r y f o r three days a f t e r p r e p a r a t i o n . The c e n t r a l g l u e l i n e was then sheared i n compression loading according t o CSA 0177-1965 f o r glued-laminated timber. However, because of equipment breakdown, blocks from PF IB-337-glued continuous i LVL were t e s t e d three weeks a f t e r machining. A T i n i u s Olsen 20,000 l b . t e s t i n g machine, f i t t e d w i t h a shearing head was used. The maximum f a i l i n g load i n shear and % wood f a i l u r e i were recorded f o r each b l o c k . Each specimen was weighed a f t e r the t e s t i n g and oven d r y i n g i n order t o e s t a b l i s h the moisture content at time of t e s t . 3.3.5.2 Cold soak In the f i n a l d r a f t of a q u a l i t y c o n t r o l program e s t a b l i s h e d f o r a l o c a l LVL manufacturer i n B.C., Bohlen 4 3 " (1972b) s p e c i f i e d a 24-hour cold-soak t e s t ( a f t e r DIN 68705) or a (vacuum/pressure) soak t e s t f o r shorter d u r a t i o n . The 24-hour c o l d soak only was used i n the broadleaf maple t e s t s , where specimens were held submerged i n water at 70 to 75°F f o r 24 hours and sheared wet afterwards. A l s o , f a i l i n g load and % wood f a i l u r e were recorded. 3.3.5.3 C y c l i c (vacuum/pressure) soak t e s t The t e s t specimens were held submerged i n water i n a r e t o r t at 70 t o 75°F. A vacuum of at l e a s t 25 inches of mercury was drawn by water vacuum f o r two hours, followed immediately by a p p l i c a t i o n of 75 t o 80 p s i f o r two hours. Specimens were removed from the r e t o r t , d r i e d f o r 14 hours i n an oven at 60°; t 5 O F at an a i r speed of 450 fpm. The vacuum/pressure c y c l e was repeated and then the specimens were t e s t e d wet. This t e s t i s between the vacuum-pressure-soak recommended by Bohlen (1972b) and the delamination t e s t of CSA 0177-1965. The l a t t e r was modified f o r use i n t h i s study i n order t o cut down length of t e s t p e r i o d . Since only the c e n t r a l g l u e l i n e would be t e s t e d , i t was assumed that the delamination t e s t s would be more info r m a t i v e because they would t e s t a l l g l u e l i n e s . Hence the delamination t e s t was c a r r i e d out according t o CSA 0177-1965. A l s o , the oven a v a i l a b l e at the time the shear t e s t was being c a r r i e d out has a forced a i r c i r c u l a t i o n of 450 fpm:.instead of the 200 to 300 fpm recommended i n CSA 0177-44 1965. I f the t e s t was not modified, the specimens would be subjected t o excessive d r y i n g s t r e s s e s . 3.3.5.4 Delamination t e s t The delamination t e s t was c a r r i e d out according to CSA 0177-1965, but length of specimens was changed i n order t o t e s t board q u a l i t y w i t h two-inch b l o c k s cut c o n s e c u t i v e l y as i n the s t r e n g t h response t e s t . Specimens were put i n a r e t o r t where they were held immersed i n water at room temperature of 70 to 75°F. Samples were separated f o r a l l end-grain surfaces t o be exposed to water. A vacuum of at l e a s t 25 inches of mercury was drawn and held f o r two hours. The vacuum,was then released and a pressure of 75 i 5 p s i was a p p l i e d f o r two,hours. The vacuum/pressure c y c l e was repeated and then the specimens were d r i e d f o r 88 hours i n a i r at 80 + 5°F and 25 to 30% r e l a t i v e humidity w i t h the a i r moving at 200 t o 300 fpm. The e n t i r e soaking-drying c y c l e was repeated twice to comprise a t o t a l t e s t period of 12 days. Following the f i n a l d rying p e r i o d , the t o t a l l e n g t h of open glue j o i n t s on the end-grain surfaces of the specimens were measured to the nearest l / 1 6 - i n c h and expres-sed, f o r the two end-grain surfaces as a percentage of the e n t i r e l e n g t h of g l u e l i n e s exposed on these s u r f a c e s . Glue.-l i n e s at knots or knotty areas were excluded from e s t i m a t i o n of delamination. 4 5 3.3.5.5 B o i l t e s t Specimens were held submerged i n b o i l i n g water f o r four hours, then d r i e d i n an oven at 145° i 5°F f o r 20 hours, held submerged again i n b o i l i n g water f o r another four hours and then cooled i n water at 70 t o 75°F. The specimens were not te s t e d i n shear but percentage delamination was measured as described f o r the delamination t e s t above. 3.3.5.6 Shear strength adjustment The moisture contents at time of t e s t were g e n e r a l l y low except f o r the blo c k s from the PF IB-337 bonded continuous LVL blo c k s which were sheared three weeks a f t e r machining. A l l dry shear strength values f o r a l l species except broadleaf maple were adjusted t o t h e i r seven percent moisture content e q u i v a l e n t s . The USDA Forest S e r v i c e (1955) devised exponential formulae f o r accurate adjustment of strength p r o p e r t i e s of wood at d i f f e r e n t moisture contents to t h e i r equivalent at a common moisture content l e v e l . Approximate values were a l s o given f o r s i t u a t i o n s where high accuracy was not expected. A three percent average increase (or decrease) i n shear strength was given f o r a one percent decrease (or increase) i n moisture content. The American N a t i o n a l Standards (1973) gave 3.7 percent f o r s t r u c t u r a l glued laminated timber. Since i t i s known t h a t l a t h e checks weaken the p l i e s i n LVL, a c o n d i t i o n absent i n laminated timber, the laminae of which are g e n e r a l l y planed and s o l i d , an approximate adjustment f a c t o r of three percent was adopted i n t h i s study. The wet shear data were not adjusted. 47 4.0 RESULTS 4.1 Small Panel Tests 4.1.1 G l u e l i n e Temperature of Broadleaf Maple, Black Cottonwood and Sugar Maple LVL Temperature r i s e of broadleaf maple LVL at a spread of 42.5 lb/MSGL, p l a t e n pressure of 200 p s i , and temperature of 300°F, and CGLT of 233°F, i s shown i n f i g u r e 8. The three c e n t r a l g l u e l i n e temperatures considered i n these stud i e s are marked by h o r i z o n t a l l i n e s on the graph. Temperature i n the CGL of broadleaf maple LVL as a f f e c t e d by s i z e and temperature of press platens and gluespreads are presented i n Table 7. A s i m i l a r study f o r b l a c k cottonwood and sugar maple i s presented i n Table 8. 4.1.2 Adequate Gluing C o n d i t i o n s f o r Broadleaf Maple LVL The ANOVA t a b l e s and s t a t i s t i c a l l y ranked means f o r three variables—maximum f a i l i n g load i n shear, shear strength and wood f a i l u r e developed at gluespreads 27;5-, 30-, and 37.5 lb/MSGL are presented i n Table 9. The ANOVA t a b l e and ranked means f o r the four l e v e l s of gluespread are presented f o r wood f a i l u r e i n the l a s t row of Table 9. Mean, standard d e v i a t i o n and c o e f f i c i e n t of v a r i a t i o n of each of the three v a r i a b l e s at the d i f f e r e n t treatment combinations are presented i n Tables 10 and 11. 4 8 E f f e c t of p l a t e n temperature and aging on the q u a l i t y of c e n t r a l g l u e l i n e bonds and the s t a t i s t i c a l l y ranked means under d i f f e r e n t treatments are presented i n Table 12. The mean, standard d e v i a t i o n and c o e f f i c i e n t of v a r i a t i o n of the three v a r i a b l e s are presented i n Table 13 f o r the four treatment combinations. Table 14 contains ANOVA t a b l e s and s t a t i s t i c a l l y ranked means of v a r i a b l e s obtained from specimens te s t e d f o r adequate c u r i n g temperature. Table 15 contains the mean values f o r treatment combinations. The e f f e c t of pressure and aging on shear strength, wood f a i l u r e and th i c k n e s s of LVL panels are presented i n Table 16. 4.1.3 Adequate Gluing C o n d i t i o n s f o r Black Cottonwood Dry shear strength at t e s t , adjusted shear strength and wood f a i l u r e were the three v a r i a b l e s used i n determining the adequate g l u i n g c o n d i t i o n s f o r black cottonwood and sugar ma pie (Table 17). For adequate gluespread, ANOVA t a b l e s , and s t a t i s t i c a l l y ranked means are presented i n Table 18. The mean values of v a r i a b l e s at v a r i o u s treatment combinations are presented i n Table 18. Tables 19 and 20 co n t a i n ANOVA t a b l e s w i t h s t a t i s t i c a l l y ranked means, and mean values f o r treatment combinations, involved i n the study of adequate pressure f o r black cottonwood. 49 4.1.4 Adequate Gluing C o n d i t i o n s f o r Sugar Maple LVL Re s u l t s f o r adequate gluespread and adequate pressure t e s t s are presented i n Tables 21, 22 and 23, 24, r e s p e c t i v e l y . V a r i a b l e s , gluespread l e v e l s , agings and t e s t s are as f o r Tables 17, 18, 19 and 20. For e f f e c t of double-pressing, f i v e v a r i a b l e s were considered. Tables 25 and 26 con t a i n ANOVA t a b l e s w i t h s t a t i s t i c a l l y ranked means, mean and v a r i a b i l i t y of strength and r e l a t e d p r o p e r t i e s ( v a r i a b l e s ) , at the d i f f e r -ent treatment combinations, r e s p e c t i v e l y . 4.1.5 Performance of MPRG i n Sugar Maple and Black Cottonwood LVL For the adequate gluespread t e s t a n a l y s i s of variance t a b l e s w i t h s t a t i s t i c a l ranking are presented i n Table 27. Mean and v a r i a b i l i t y of strength p r o p e r t i e s under the d i f f e r -ent treatment combinations are presented i n Table 28. To i n v e s t i g a t e bond q u a l i t y of bl a c k cottonwood LVL laminated w i t h MPRG, ANOVA t e s t was c a r r i e d out f o r dry shear strength and wood f a i l u r e . The r e s u l t s are presented i n Table 29. Mean and v a r i a b i l i t y at the v a r i o u s treatment combinations are presented i n Table 30. 4.2 Continuous LVL Tests 4.2.1 Mean Values f o r Continuous LVL S e c t i o n s Mean and v a r i a b i l i t y of each of the three s e c t i o n s of the continuous LVL board are presented i n Table 31. The 50 v a r i o u s combinations of speci e s , aging, glue and s e c t i o n are shown. 4.2.2 G l u e l i n e Temperature of Continuous LVL • Temperature r i s e curves f o r the three c r i t i c a l p o i n t s i n the LVL board during continuous production are presented i n f i g u r e 9. Temperature d i s t r i b u t i o n w i t h i n LVL during the press schedule and the average r i s e at the v a r i o u s p o i n t s w i t h i n the boards, are presented i n Table 32. The wood species, p l a t e n pressure and glue combinations are shown on the t a b l e . 4.2.3 Strength Q u a l i t y Response to Continuous Laminating Process Dry and adjusted shear strength and wood f a i l u r e along the l e n g t h of continuous boards are presented graph-i c a l l y i n f i g u r e s 10 to 19. The three s e c t i o n s of board are i d e n t i f i e d . The e f f e c t s of aging are a l s o shown. Trends are shown f o r d i f f e r e n t wood species/glue combinations. 4.2.4 Delamination Test Average delamination i n each of the three s e c t i o n s f o r wood species/glue combinations are shown i n Tables 33 and 34. R e s u l t s i n Table 33 were obtained from specimens t e s t e d by c y c l i c vacuum/pressure/dry delamination of LVL while those i n Table 34 were obtained from b o i l / d r y / b o i l t e s t of PF IB-334-bonded LVL. 51 5.0 DISCUSSION 5.1 Small Panel Tests 5.1.1 Press Schedule f o r Broadleaf Maple Bohlen (1972a) used a 20-minute press time, 200 p s i pressure and 30 lb/MSGL of glue i n h i s D o u b l a s - f i r LVL study. Using s i m i l a r pressing c o n d i t i o n s of 200 p s i and 300°F p l a t e n pressure and temperature, r e s p e c t i v e l y , the same gluespread of 30 lb/MSGL, and same glue, PF IB-337, BMP LVL reached a CGLT of 233°F i n 32 minutes. This press-ing time was f o r 16 by 16 i n . panels r a t h e r than 54 by 54 i n . panels. The CGLT, while using gluespread of 42.5 l b / MSGL, reached 240°F i n 25 minutes when the la r g e press at pla t e n temperature 350°F was used. The longer press time w i t h BMP LVL was expected because BMP i s denser than D o u g l a s - f i r . Although conduct-i v i t y of BMP i s higher than t h a t of D o u g l a s - f i r (MacLean 1941), i t s r a t e of temperature r i s e i s decreased by i t s higher s p e c i f i c heat. According t o MacLean (1930, 1932) d i f f u s i v i t y , ^ which i s a measure of rate of change of temperature can be expressed by the equation h 2 = J<_ n ce ' where: h 2 i s the d i f f u s i v i t y , K the thermal c o n d u c t i v i t y ; c, the d e n s i t y and e, the s p e c i f i c heat. Consequently, w i t h i n 16 D i f f u s i v i t y i s i n inch-second-degree, thermal c o n d u c t i v i t y , i n Btu/hr/ft2/°F/in. and s p e c i f i c heat i n Btu. 52 certain l i m i t s , the denser wood should have a lower r a t e of change of temperature and hence a longer press time than a l e s s dense wood. The veneers w i t h zero gluespread heated f a s t e r than the gluespread ones. Although MacLean (1955) concluded t h a t glue does not appreciably a l t e r the c o n d u c t i v i t y of plywood panels, the presence of e x t r a m a t e r i a l to heat g e n e r a l l y increases time t o r a i s e CGLT. Data presented i n Table 7 confirm that the higher the p l a t e n temperature, the lower the press time required to reach a s p e c i f i e d CGLT. Table 7 a l s o shows t h a t the higher the gluespread, the longer the press time. 5.1.2 Adequate Gluespreads f o r Broadleaf Maple LVL The ANOVA of maximum load i n shear, shear strength and wood f a i l u r e developed at spreads 27.5-, 30- and 37.5 lb/MSGL under dry and 24 hour c o l d soak agings show the f o l l o w i n g (see Table 9): (a) There was no s i g n i f i c a n t d i f f e r e n c e between maximum load at spread 27.5 and 30 lb/MSGL, but value at spread 42.5 lb/MSGL was s i g n i f i c a n t l y higher than f o r the lower spreads. The same i s true f o r shear s t r e n g t h . The three spread l e v e l s showed s i g n i f i c a n t d i f f e r e n c e s i n wood f a i l u r e . In a l l cases, the 24-hour c o l d soak s i g n i f i c a n t l y reduced the three strength p r o p e r t i e s . The ANOVA t a b l e i n the l a s t row of Table 9 showed 53 no s i g n i f i c a n t d i f f e r e n c e between wood f a i l u r e at spreads 37.5- and 42.5 lb/MSGL. This a n a l y s i s , done w i t h sub-samples of 5, was l e s s s e n s i t i v e than t h a t c a r r i e d out w i t h samples of 10 because as shown by the l a t t e r , the wood f a i l u r e at spreads of 27.5- and 30 lb/MSGL d i f f e r e d . Larger samples might p o s s i b l y show s i g n i f i c a n t d i f f e r e n c e between the two higher spreads. In essence, the strength p r o p e r t i e s developed w i t h a spread of 42.5 lb/MSGL would be higher than those developed w i t h the three lower spreads. The American N a t i o n a l Standard A 190.1-1973 (PS 56-73) s p e c i f i e s a minimum of 80 percent average wood f a i l u r e f o r wet-use adhesives used w i t h a l l species and f o r dry-use adhesives used w i t h softwoods and non-dense hardwoods. A minimum of 90 percent of c l e a r lumber shear strength p a r a l l e l t o g r a i n was s p e c i f i e d f o r laminated timber. Tables 10 and 11 show th a t specimens w i t h 27.5-and 30 lb/MSGL gluespread f a i l e d both i n dry and wet shear and those w i t h 37.5 lb/MSGL passed only i n dry shear. Table 11 shows that bonds produced at 42.5 lb/MSGL spread passed at both dry and c o l d soak. The average strength values showed a general trend of i n c r e a s i n g strength w i t h i n c r e a s i n g gluespread (Tables 10 and 11). This agrees w i t h the f i n d i n g of F i s c h e r and Bensend (1969) i n t h e i r study of southern pine, which i s a porous softwood, that shear strength continued t o r i s e , and 54 maximum gluespread of 90 lb/MSGL (higher than maximum gluespread i n t h i s study) gave maximum wood f a i l u r e . The c o l d soak t e s t reduced maximum load by 74, 66, 66 and 66 percent f o r spreads of 27.5, 30, 37.5 and 42.5 lb/MSGL, r e s p e c t i v e l y , shear strength by 75, 68, 70 and 68 percent, r e s p e c t i v e l y , and wood f a i l u r e by 68, 47, 24 and 11 percent, r e s p e c t i v e l y . I t should be noted that part of the r e d u c t i o n was due to presence of water. However, high r e d u c t i o n i n strength was not expected because CGLT was r a i s e d t o 233°F before the press was opened, and hence proper cur i n g of glue was expected. This CGLT was higher than the 220°F reported f o r the plywood i n d u s t r y ( J a r v i 1967; Chow et a l . 1973, and Shelton 1969). This corroborates the warning of Chow et a l . (1973) that the i n d u s t r y should ensure that CGLT reached the proper temperature p r i o r to hot stacking i f the CGLT i s to reach adequate c u r i n g temperature. S a t u r a t i o n of specimens w i t h water (Chunsi 1973) and presence of lathe checks (Bohlen 1972a, and Schaffer et a l . 1972) and p o s s i b l y , undercure of g l u e l i n e were r e s p o n s i b l e f o r the s u b s t a n t i a l strength r e d u c t i o n . Although average wood f a i l u r e at 42.5 lb/MSGL spread was 85 percent i t was considered quite low although i t passed the 80 percent wood f a i l u r e s p e c i f i c a t i o n of the American N a t i o n a l Standard PS 56-73. I t was considered quite low because of the presence of lathe checks which u s u a l l y increase wood f a i l u r e . 55 5.1.3 E f f e c t of Pl a t e n Temperature The ANOVA (Table 12) showed that panels heated t o CGLT of 2 3 3 ° F using 300OF and 4 0 0 ° F p l a t e n s d i d not show any s i g n i f i c a n t d i f f e r e n c e i n e i t h e r maximum l o a d , shear strength or wood f a i l u r e . This showed that p l a t e n temperature d i d not have any s i g n i f i c a n t e f f e c t on CGL of LVL but the temperature t o which the CGL was heated. In essence, i t i s the degree of cure of the CGL that matters, not the p l a t e n c o n d i t i o n used. The s i g n i f i c a n t d i f f e r e n c e i n the aging t e s t showed that the CGL was weakened by aging. Mean dry strength values (Table 13) showed s l i g h t l y higher values f o r panels pressed at 300°F than f o r those pressed w i t h 4 0 0 ° F p l a t e n s , except f o r the dry wood f a i l u r e which was 96 percent i n e i t h e r case. The aged specimens showed higher values i n panels heated w i t h 4 0 0 ° F platens thanvin those heated w i t h 3 0 0 ° F p l a t e n s . At the two pla t e n temperatures, averages of maximum load were 2500 and 2114 l b . , shear strength, 575 and 477 p s i , r e s p e c t i v e l y , while average wood f a i l u r e of panels were 83 t o 85 percent f o r the two p l a t e n temperatures, r e s p e c t i v e l y . These d i f f e r e n c e s are q u i t e large though not s i g n i -f i c a n t at 0.05 l e v e l as shown above. 5.1.4 Adequate Curing Temperature Panels heated t o CGLT 2330>, 2400 and 3 0 0 ° F were t e s t e d dry, c o l d soaked and c y c l i c (vacuum/pressure) soaked 56 and analysed f o r d i f f e r e n c e of means (Table 14). The p l a t e n temperatures used were ignored, on the b a s i s of the t e s t above. Maximum load and shear strength showed no s i g n i f i -cant d i f f e r e n c e between panels at CGLT 1 and 2. S i m i l a r l y they showed no s i g n i f i c a n t d i f f e r e n c e between panels at CGLT 2 and 3. That i s , only panels at CGLT 1 and 3 were s i g n i f i c a n t l y d i f f e r e n t . The maximum load and shear strength were not s i g n i f i c a n t l y d i f f e r e n t a f t e r 24-hour c o l d soak and c y c l i c (vacuum/pressure) soak, though they were s i g n i f i c a n t l y higher when t e s t e d dry than a f t e r the two a c c e l e r a t e d agings. These r e s u l t s show than at an 0.05 l e v e l of s i g n i f i -cance CGLT3, (300°F) does not produce a b e t t e r bond than CGLT2 (240°F). S i m i l a r l y , the 24-hour c o l d soak and the c y c l i c (vacuum/pressure) soak do not d i f f e r s i g n i f i c a n t l y i n t h e i r aging e f f e c t on shear specimens. Wood f a i l u r e showed the e f f e c t s of CGLT more c l e a r l y because while there was no s i g n i f i c a n t d i f f e r e n c e between CGLT of 240 and 300°F, i t showed that e i t h e r of them produced s i g n i f i c a n t l y higher wood f a i l u r e than CGLT of 233°F. Maximum load and shear strength d i d not show s i g n i f i c a n t d i f f e r e n c e between CGLT 1 and 2. This b e t t e r estimate of bond d u r a b i l i t y obtained w i t h wood f a i l u r e agrees w i t h the c o n c l u s i o n of Northcott and Colbeck ( i 9 6 0 ) , and Northcott et a l . (1963), that w i t h i n l i m i t s , percent wood f a i l u r e was a p o t e n t i a l l y good 57 estimator of plywood d u r a b i l i t y . In an e a r l i e r work, Northcott (1955) had po s t u l a t e d t h a t there was poorer c o r r e l a t i o n between breaking load and s e r v i c e l i f e than between percent wood f a i l u r e and s e r v i c e l i f e . The average wood f a i l u r e values presented i n Table 15 were highest at CGLT 240°F i r r e s p e c t i v e of aging and were lowest at CGLT 233°F. These r e s u l t s , i n c l u d i n g the ANOVA, j u s t i f y the acceptance of 240°F as an adequate c u r i n g temperature t o be a t t a i n e d i n the press t o ensure adequate cure of these phenolic r e s i n s during hot stacking of LVL. This 240°F minimum was adopted i n the small panel t e s t s . 5.1.5 E f f e c t of P l a t e n Pressures Pressures of 250 and 275 p s i showed considerable increase i n shear strength and wood f a i l u r e over the values f o r panels pressed at 200 p s i (Table 16). Net t h i c k n e s s of specimens made at 200, 250 and 275 p s i are 1.548, 1.351 and 1.296 inches, r e s p e c t i v e l y . The l a t t e r two are e v i d e n t l y lower than the nominal 2-inch t h i c k n e s s r e q u i r e d f o r an LVL j o i s t or stud. While specimens made at 200 p s i showed an increase i n t h i c k n e s s of 5.8 and 7.2 percent during c o l d soak and c y c l i c aging, r e s p e c t i v e l y , those made at 250 p s i increased by 16.1 and 20.0 percent, r e s p e c t i v e l y and those made at 275 p s i swelled by.21.7 and 24.4 percent, respec-t i v e l y . Broadleaf maple LVL pressed at 250 and 275 p s i 58 therefore, showed severe dimensional movement, which was. probably due t o over compression during manufacture. For dry-use c o n d i t i o n s and i n s t r u c t u r a l uses where t h i c k n e s s i s not l i m i t i n g , using these higher p l a t e n pressures f o r broadleaf maple LVL would be advantageous. They would be h i g h l y l i m i t e d i n wet use s i t u a t i o n s . The broadleaf maple LVL study proved the f o l l o w i n g general g l u i n g c o n d i t i o n s : that gluespread of 42.5 lb/MSGL gives b e t t e r r e s u l t s than lower gluespreads, CGLT and not pla t e n temperature determines CGL bond s t r e n g t h , and CGLT of 240°F i s p r e f e r a b l e t o e i t h e r 233 or 300°F, while using PF IB-337. S p e c i f i c a l l y , broadleaf maple LVL at a spread of 42.5 lb/MSGL would r e q u i r e a press time of about 25 minutes to get CGL to 240°F when using a 54-inch by 54-inch press heated t o 350°F and maintained at 200 p s i . A small 16 by 16-inch press at 300°F and 200 p s i would take about 40 minutes. A l s o , a press pressure of 200 p s i would be , p r e f e r r e d t o e i t h e r of 250 or 275 p s i . 5.1.6 Black Cottonwood and Sugar Maple Studies As shown i n Table 5, the pee l i n g c h a r a c t e r i s t i c s of b l a c k cottonwood and sugar maple veneers were much b e t t e r than corresponding values f o r broadleaf maple veneers (pa9e2.t)» I f pee l i n g c h a r a c t e r i s t i c s are the main deter-mining f a c t o r s f o r using high gluespreads, then black cottonwood and sugar maple would r e q u i r e lower spreads. 59 5.1.6.1 Press schedules f o r black cottonwood and sugar maple LVL The b l a c k cottonwood LVL panels took 27.5, 31 and 35 minutes, at gluespreads of 30, 37.5 and 42.5 f o r the CGL t o heat up t o 240°F. P l a t e n s i z e of 16 by 16 inches and temperature of 350OF were used. At the time the 240°F CGLT was reached the outer g l u e l i n e a t t a i n e d 299, 300 and 309°F at the three gluespreads. The non-glued panels reached 240 t 1°F w i t h i n 15 t o 18 minutes and the outer g l u e l i n e reached 288 t o 295°F w i t h i n the same p e r i o d . These show the same trend of press time w i t h gluespread as shown by broadleaf maple. A l s o , by the time CGL was heated t o 240°F, the CGL had reached temperatures which preclude undercure. Sugar maple LVL a l s o showed the same t r e n d , the CGLT reaching 240°F i n 17.3 t o 20.25 minutes f o r gluespreads ranging from zero t o 42.5 lb/MSGL.' The press times presented i n Table 8 a r e , s t r i c t l y speaking, not comparable. This i s because the i n i t i a l temperature of the assemblies d i f f e r e d i n the b l a c k c o t t o n -wood and sugar maple LVL. A f a c t o r X, c a l c u l a t e d by d i v i d i n g change i n temperature of CGL over the pressing period by the press time, i s considered more comparable. In a l l species s t u d i e d , the higher the gluespread, the lower was f a c t o r X and the higher the plat e n temperature (see Table 7 ) , the higher was f a c t o r X. The nearer the g l u e l i n e t o the p l a t e n , the higher i s the f a c t o r X. Over a long press time, the gradient between f a c t o r X of the c e n t r a l and outer 60 gluelin.es diminished. This was shown by the data f o r the double-pressed panels i n Table 8. The e f f e c t of pressure on press time was s l i g h t . The CGL of sugar maple LVL panels pressed at 275 p s i a t t a i n e d 240°F, 1.5 minutes f a s t e r than t h a t f o r panels pressed at 250 p s i . There was no d i f f e r e n c e i n press time of black cottonwood LVL pressed at 69 and 100 p s i , r e s p e c t i v e l y . Other f a c t o r s such as the s l i g h t d i f f e r e n c e s i n t h i c k n e s s of boards, presence or absence of knots and knot holes i n the assemblies may a l s o have had an e f f e c t on press time. I n v e s t i g a t i o n of such f a c t o r s were beyond the scope of t h i s study. 5.1.7 Adequate Gluespread f o r Black Cottonwood LVL A n a l y s i s of variance (Table 17) showed th a t each of shear strength, adjusted shear strength and wood f a i l u r e was s i g n i f i c a n t l y d i f f e r e n t at spreads of 30, 37.5 and 42.5 lb/MSGL, consequently showing that spread 42.5 lb/MSGL was superior t o a l l others. The c y c l i c (vacuum/pressure) soak a l s o s i g n i f i c a n t l y reduced the three strength c h a r a c t e r i s t i c s of LVL. The strength values f o r i n d i v i d u a l spread/aging combination (Table 18) showed progressive increase from the lowest to the highest gluespreads studied. The same trend was observed both i n the dry and c y c l i c (vacuum/pressure) soak specimens. Dry shear specimens showed wood f a i l u r e of 42, 88, and 95 percent, r e s p e c t i v e l y , while the aged specimens showed wood f a i l u r e of 18, 71, and 87 percent, 61 r e s p e c t i v e l y . Only the 42.5 lb/MSGL specimens passed the minimum 80 percent requirement of the American N a t i o n a l Standards PS 56-73. V a r i a b i l i t y of the s t r e n g t h c h a r a c t e r i s t i c s decreased from the lowest t o the highest spreads studied and was higher i n the c y c l i c (vacuum/pressure) soak than i n the dry specimens. The gradient of v a r i a b i l i t y between the two agings a l s o decreased w i t h i n c r e a s i n g spread l e v e l . T his lower v a r i a b i l i t y suggests that as bond improved, g l u e l i n e c h a r a c t e r i s t i c s became more uniform. 5.1.8 Adequate P l a t e n Pressure f o r Black Cottonwood LVL A n a l y s i s of variance showed that strength c h a r a c t e r -i s t i c s (shear strength and wood f a i l u r e ) of panels pressed at 100 p s i press pressure were s i g n i f i c a n t l y higher than f o r those pressed at 69 p s i (Table 19). The p l a t e n pressure/ aging combinations (Table 20) showed wood f a i l u r e of 97 compared to 87 percent f o r panels pressed at 100 p s i and 69 p s i , r e s p e c t i v e l y a f t e r aging. The dry t e s t wood f a i l u r e s were 99 and 95 percent, r e s p e c t i v e l y . This shows that the s u p e r i o r i t y of bonds produced at 100 p s i over t h a t produced at 69 p s i was more pronounc'ed a f t e r aging. Dry t e s t shear strengths were 1228 and 1097 p s i and adjusted shear strengths were 1156 and 1034 p s i , r e s p e c t i v e -l y , f o r the two pressure l e v e l s , while the c y c l i c (vacuum/ pressure) soak specimens showed shear strengths of 566 and 450 p s i , r e s p e c t i v e l y . 62 The improved strength values must have r e s u l t e d .. from the more intimate mating of the wood surfaces caused by higher pressure. Average t h i c k n e s s of b l a c k cottonwood LVL pressed at 69 p s i and t e s t e d dry was 1.509 inches. I t was 1.456 inches at 100 p s i . The c y c l i c aged eq u i v a l e n t s had mean t h i c k n e s s of 1.568 and 1.506 inches r e s p e c t i v e l y . These represent thickness increases of 3.9 and 3.2 percent. Thickness of black cottonwood LVL panels produced at p l a t e n pressure of 100 p s i was not s u b s t a n t i a l l y lower than that f o r panels produced at 69 p s i . Thickness i n e i t h e r case was quite c l o s e to the nominal 2-inch dimension f o r stud or j o i s t lumber. .Dimensional movement during aging was not excessive. Shear strength value f o r small c l e a r specimens of s o l i d sawn b l a c k cottonwood published by Kennedy (1965) f o r shear p a r a l l e l t o g r a i n i n t a n g e n t i a l plane i s 1157 p s i f o r a i r dry (12 percent MC) c o n d i t i o n and 770 p s i at green c o n d i t i o n . The a i r dry shear strength, adjusted t o the seven percent MC e q u i v a l e n t , using the approximate conversion f a c t o r of three f o r every percent moisture change as suggest-ed by the USDA f o r e s t s e r v i c e (1955), becomes 1331 p s i . The shear value of black cottonwood LVL s i m i l a r l y adjusted becomes 1156 p s i which equals 87 percent of the s o l i d lumber equ i v a l e n t . The shear strength of c y c l i c (vacuum/pressure) soak LVL specimens was 566 p s i or 74 percent of published green f i g u r e s (Table 36). 63 These shear strength values of black cottonwood LVL are qu i t e high percentage-wise, bearing i n mind that the veneers were of r e l a t i v e l y poor q u a l i t y compared w i t h the small c l e a r specimens used i n Kennedy's study. S c h a f f e r et a l . (1972) reported Pres-Lam shear strength which was 67 percent of s o l i d sawn c o n t r o l s . 5.1.9 Adequate Gluespread f o r Sugar Maple LVL There was s i g n i f i c a n t i n t e r a c t i o n between spread and aging i n the ANOVA of dry t e s t shear strength (Table 21). No such i n t e r a c t i o n occurred i n ANOVA of wood f a i l u r e which showed s i g n i f i c a n t d i f f e r e n c e between spreads 30, 37.5 and 42.5 lb/MSGL, and between values at dry t e s t and a f t e r c y c l i c (vacuum/pressure) soak aging. Adjusted shear strength at spread/dry t e s t combina-t i o n s showed s i g n i f i c a n t d i f f e r e n c e between the three combinationSi Strength values at the spread/aging combinations p r o g r e s s i v e l y increased w i t h i n c r e a s i n g gluespread i r r e s p e c -t i v e of aging (Table 22). The wood f a i l u r e s recorded at the d i f f e r e n t spread l e v e l s were q u i t e comparable w i t h those produced by black cottonwood LVL. As expected, shear strengths at which these wood f a i l u r e s were produced were much higher i n sugar maple LVL than i n bl a c k cottonwood LVL (see Tables 18 and 21). V a r i a b i l i t y decreased w i t h glue-spread i r r e s p e c t i v e of aging. In the l i g h t of the same trend i n strength p r o p e r t i e s 64 i n both b lack cottonwood and sugar maple LVL, i t was not understood why the i n t e r a c t i o n term should be so h i g h l y s i g n i f i c a n t i n sugar maple ( f o r shear strength) while not s i g n i f i c a n t i n black cottonwood LVL. P o s s i b l y because of the t i g h e r p e e l , and lower p o r o s i t y (of gr a i n ) of the sugar maple veneers, more of the glue remained i n the g l u e l i n e than w i t h poplar. This would increase the t h i c k -ness of the g l u e l i n e and i f under the g l u i n g c o n d i t i o n s there was undercure, the t h i c k e r the g l u e l i n e , the higher would be the percentage of undercure, and hence the l a c k of water-proofness of g l u e l i n e . A l s o , the t h i c k e r the g l u e l i n e the higher the tendency t o develop micro cracks which would lead t o g l u e l i n e f a i l u r e when s t r e s s e d . This.would r e s u l t i n high i n t e r a c t i o n between gluespread and aging. Very low pressure would a l s o have the same e f f e c t on g l u e l i n e t h i c k -ness. 5.1.10 Adequate P l a t e n Pressure f o r Sugar Maple LVL The r e s u l t s of both wood f a i l u r e and shear strength show s i g n i f i c a n t i n t e r a c t i o n of pressure and aging (Table 23). The adjusted shear strength showed s i g n i f i c a n t l y higher values at 275 p s i pressure than at 250 p s i . The higher pressure improved both the shear strength and wood f a i l u r e i r r e s p e c t i v e of the aging. V a r i a b i l i t y of dry strength increased w i t h pressure contrary t o ex p e c t a t i o n , but the aged samples had lower v a r i a b i l i t y at the higher 65 pressure. The l a t t e r was t r u e of both dry and aged samples of sugar maple LVL (Table 24). -5.1.11 Small Panel Study, Summary and Comments These t e s t s have shown that good q u a l i t y LVL can be produced from black cottonwood and sugar maple ^ - i n c h veneers. G l u i n g c o n d i t i o n s were: maximum gluespread of 42.5 lb/MSGL of phenol-formaldehyde glue IB-337, CGLT of 240°F a t t a i n e d i n the press, 100 p s i and 275 p s i f o r the two s p e c i e s , r e s p e c t i v e l y , and p l a t e n temperature of 350°F. This high gluespread would introduce s u b s t a n t i a l moisture i n t o the g l u e l i n e . Table 36 shows that the s t r e n g t h of CGL produced under these c o n d i t i o n s compares favourably w i t h c l e a r s o l i d lumber except f o r broadleaf maple LVL. At the average c o n d i t i o n of veneers given i n Table 5, and the glue mixes given i n appendices IV(a) and I V ( b ) , and using the formula developed by Freas and Selbo (1947), PF IB-337 would increase moisture content of black c o t t o n -wood sugar maple LVL lay-up by 0.93 and 0.53 percent, r e s p e c t i v e l y . I n the l i g h t of the long press time, high 1 7 / \ Increase i n moisture content (percent) i s : W/100 x G x (L - 1) i m = 0.000192 WG L - 1 T x L x 1000 x S x 62.5 TS L 12 where* ^ = P o u n <^ s °^ water i n 100 l b . of mixed glue; G = pounds of mixed glue used per thousand square fe e t of g l u e - j o i n t area; L = number of l a m i n a t i o n s ; L - 1 = number of g l u e l i n e s i n glued assembly; T = average l a m i n a t i o n t h i c k n e s s ( i n i n c h e s ) ; S = s p e c i f i c g r a v i t y of wood ( d r y ) . 66 p l a t e n temperature and low i n i t i a l moisture content veneers, t h i s a d d i t i o n a l moisture would o f f e r no d i s -advantage and even would o f f e r a ' l i t t l e help i n reducing the tendency of laminations to oven-dry during p r e s s i n g . Glue PF IB-334 added 1.25 and 0.71 percent, r e s p e c t i v e l y , t o the black cottonwood and sugar maple glued LVL assembly. The long press time makes the economic f e a s i b i l i t y of t h i s wood product questionable except i t could be d r a s t i c a l l y reduced. This i s f u r t h e r discussed below. 5.1.12 Adequate Gluespread of Phenol-Resorcinol Glue w i t h Sugar Maple The ANOVA of wood f a i l u r e (Table 27) showed s i g n i f i c a n t d i f f e r e n c e between panels at spreads of 37.5 and 42.5 lb/MSGL. Aging d i d not reduce wood f a i l u r e s i g n i f i c a n t l y at the 0.05 l e v e l . This i s an expected improvement over the phenolic r e s i n s used i n t h i s study. Shear strength showed s i g n i f i c a n t i n t e r a c t i o n between gluespread and aging. This a l s o happened w i t h PF IB-337-bonded sugar maple LVL (Table 21). This i n t e r -a c t i o n thus appears t o be a f a c t o r inherent i n sugar maple and probably not w i t h the glue used. Adjusted shear strength at the two spread l e v e l s were s i g n i f i c a n t l y d i f f e r e n t at the 0.05 l e v e l . The dry shear strengths developed were higher at 67 37.5 lb/MSGL gluespread than at 42.5 lb/MSGL, but a f t e r aging, the shear strength was higher at 42.5 lb/MSGL than at 37.5 lb/MSGL spread (Table 28). Under both dry and c y c l i c (vacuum/pressure) soak, wood f a i l u r e was higher at 42.5 than at 37.5 lb/MSGL spreads. Fr om t h i s and other cases noted above, where the s u p e r i o r i t y of the bond at higher glue-spreads showed more c l e a r l y a f t e r aging, i t can be concluded that dry shear strength values tend to mask the a c t u a l q u a l i t y of bond s t r e n g t h . In MPRG-bonded sugar maple LVL, shear strengths developed at spreads of 37.5 and 42.5 lb/MSGL were decreased by 56 and 44 percent, r e s p e c t i v e l y , and wood f a i l u r e , by 2.8 and 0 percent, by c y c l i c (vacuum/pressure) soak. This aging reduced bond strength of PF IB-337-bonded sugar maple LVL by 59 and 4.5 percent i n shear strength and wood f a i l u r e , respec-t i v e l y . This decrease i s higher than 44 and 0 percent given f o r MPRG-bonded sugar maple at 42.5 lb/MSGL gluespread reported above. Chunsi (1973) recorded a shear strength r e d u c t i o n of 37 percent f o r laminated timber of In (Dipterocarpus tuber- c u l a t u s Roxb.) having a s p e c i f i c g r a v i t y of 0.67 which i s s i m i l a r t o th a t of sugar maple. Since he used s o l i d planed lumber, the d i f f e r e n c e may be due t o lat h e checks and surface roughness of the ^ - i n c h veneers used. The sugar maple LVL bonded w i t h p h e n o l - r e s o r c i n o l glue (MPRG) and pressed at 275 p s i and w i t h a gluespread of 42.5 lb/MSGL, developed higher wood f a i l u r e than i t s PF IB-337 bonded counterpart, and samples were l e s s 68 v a r i a b l e (Tables 24 and 28). These a l s o agreed w i t h the f i n d i n g s of Chunsi (1973). The wood f a i l u r e developed was a l s o not s i g n i f i c a n t l y reduced by c y c l i c (vacuum/ pressure) soak, u n l i k e that developed w i t h PF IB-337. 5.1.13 Bond Strength w i t h Black Cottonwood As w i t h sugar maple LVL, the wood f a i l u r e s at the two agings were very high, here 99.9 and 99.7 r e s p e c t i v e l y . Dry t e s t wood f a i l u r e was not s i g n i f i c a n t l y reduced by aging (Table 29). The wood f a i l u r e values were s l i g h t l y higher than i n PF IB-337-bonded b l a c k cottonwood LVL (Table 20). The average shear and wood f a i l u r e values (Table 30) showed some improvement over PF IB-337 p e r f o r -mance i n the aged samples. The MPRG-bonded LVL developed 581 p s i shear strength and 99.7 percent wood f a i l u r e , w hile PF IB-337 bonded LVL developed.566 p s i shear strength and 97.3 percent wood f a i l u r e . As i n the sugar maple LVL, dry t e s t samples scored higher adjusted shear strength i n PF IB-337-bonded than i n MPRG-bonded b l a c k cottonwood LVL, whereas the reverse was true a f t e r the aging t e s t . C y c l i c (vacuum/pressure) soak decreased the dry shear strength and wood f a i l u r e by 41 and 0.2 percent, r e s p e c t i v e l y . These compare favourably w i t h the c o r r e s -ponding 54 and 1.9 percent r e d u c t i o n c a l c u l a t e d from Table 20, f o r panels pressed at 100 p s i i n PF IB-337 bonded LVL. 69 5.1.14 E f f e c t of Double-Pressing Of the f i v e v a r i a b l e s t e s t e d i n e i g h t combinations, only i n one v a r i a b l e was the i n t e r a c t i o n term not s i g n i f i -cant (Table 25). In the t e s t , ANOVA f o r moisture content of samples at aging 1, the specimens showed s i g n i f i c a n t l y d i f f e r e n t moisture content between panels pressed f o r 20 minutes only (press time l ) and those pressed i n two 20-minute press c y c l e s - w i t h a three minute i n t e r v a l (press time 2 ) . I t d i d not d i f f e r s i g n i f i c a n t l y between glues. Adjusted shear strength at the two pressing times d i f f e r e d s i g n i f i c a n t l y f o r each of the glues. Thickness of LVL at aging 1 showed n o n - s i g n i f i c a n t F-values f o r any of pressing time, glue type and t h e i r i n t e r a c t i o n term. Hence, t h i c k n e s s of panels d i d not s i g n i -f i c a n t l y d i f f e r i r r e s p e c t i v e of treatment/glue. Strength values of samples glued w i t h PF IB-337 were s u b s t a n t i a l l y lower f o r panels double-pressed than f o r those pressed once whereas the reverse was tru e f o r those glued w i t h PF IB-334. This decrease i n strength at high temperature agrees w i t h wood f a i l u r e values obtained f o r broadleaf maple LVL at CGLT of 300°F, which were s l i g h t l y lower than values at CGLT of 240°F (Table 15). T h i s s t r e n g t h r e d u c t i o n i s unusual. Moisture content of double-pressed panels was lower than that of s i n g l e pressed panels. A f t e r c y c l i c (vacuum/ pressure) soak, the double-pressed panels had higher moisture content than those single-pressed (Table 26). This i s 70 ra t h e r unusual because d e n s i f i c a t i o n and heat s t a b i l i z a -t i o n should reduce moisture pick-up of the double-pressed panels. A comparison of glues at pressing time of 20 minutes shows th a t PF IB-337-glued panels developed higher shear strengths and wood f a i l u r e than PF IB-334-glued panels. This was expected because PF -IB-337 was the glue o r i g i n a l l y m o d i f i e d 1 f o r LVL production whereas PF IB-334 was t r i e d only because of i t s higher dryout t o l e r a n c e . The l a t t e r glue may, t h e r e f o r e , have not developed f u l l bonds w i t h i n the s p e c i f i e d press time. This agrees w i t h the manufacturer's a d v i c e ^ that PF IB-334 has a slower r a t e of cure than PF IB-337. Depending on the wood used, q u a l i t y of g l u e l i n e may or may not be s u b s t a n t i a l l y a f f e c t e d by prolonged heating though d i f f e r e n c e s i n moisture content may cause adverse h y g r o s c o p i c i t y problems. Thickness i s not s u b s t a n t i a l l y a l t e r e d i f the same pressure i s ap p l i e d throughout the press c y c l e s . When s i n g l e - and double-pressed bands occur i n a continuous board, some b u i l t - i n d e f e c t s may r e s u l t . 5.2 Continuous LVL Study 5.2.1 Average Strength C h a r a c t e r i s t i c s of Board S e c t i o n s The CGL q u a l i t y of continuous LVL produced by the P r i v a t e communication w i t h W.C. A i n s l i e (Wood Laboratory Manager, Reichhold Chemicals L t d . , Port Moody, Canada, 9th August 1973 (Appendix V ) . 71" process described by Bohlen was evaluated on the b a s i s of whether or not the three s e c t i o n s passed the American N a t i o n a l Standard P.S. 56-73, and v a r i a t i o n s of the t h i c k -ness and moisture content of board s e c t i o n s were examined. The adjusted value of shear p a r a l l e l t o g r a i n published by Kennedy (1965) was used i n place of shear s t r e n g t h p a r a l l e l t o g r a i n as determined according t o ASTM D255_5-70, s p e c i f i e d i n P.S. 56-73. Adjusted shear strength of LVL l e s s than 90 percent of the adjusted published equivalent (Table 35) was considered f a i l e d . P u blished f i g u r e s f o r white spruce were 670 and 985 p s i , f o r green and a i r dry shear strength p a r a l l e l t o g r a i n , r e s p e c t i v e l y (Kennedy 1965). The a i r dry (approximately 12 percent MC) was adjusted to 1132 p s i at approximately seven percent. From adjusted shear strength and wood f a i l u r e f i g u r e s presented i n Table 32, and i n f o r m a t i o n on s o l i d lumber i n Table 35, Table 36 was prepared and i t shows the f o l l o w i n g : ( i ) I r r e s p e c t i v e of glue or aging, continuous sugar maple LVL boards f a i l e d the s p e c i f i c a t i o n f o r laminated timbers. S e c t i o n s l a n d 2 passed the wood f a i l u r e s p e c i f i c a -t i o h w h i l e they f a i l e d the shear strength s p e c i f i c a t i o n . Sec-t i o n 3 performed poorly i n a l l treatments. The f a i l u r e of sections 1 and 2 i n shear may be a t t r i b u t e d t o peeling c h a r a c t e r i s t i c s such as l a t h e checks and roughness of mating surfaces. These have been stated i n the l i t e r a t u r e t o reduce shear strength though they have a tendency to increase wood f a i l u r e . 72 ( i i ) S e c t i o n s 1 and 2 of PF IB-337-bonded black cottonwood LVL passed while s e c t i o n 3 f a i l e d the dxy t e s t s p e c i f i c a t i o n s . The aged specimens showed a s i m i l a r r e s u l t f o r the s e c t i o n s . The dry t e s t w i t h PF IB-334-bonded LVL passed i n a l l three s e c t i o n s , but s e c t i o n 3 f a i l e d the wet t e s t . ( i i i ) White spruce. LVL passed the s p e c i f i c a t i o n s i r r e s p e c t i v e of treatment, except s e c t i o n 1 which developed 74 percent wood f a i l u r e a f t e r aging. This low wood f a i l u r e was observed t o be due t o allowable d e f e c t s i n the veneers of the two c e n t r a l p l i e s . Because of complete delamination of the outer glue-l i n e i n some s e c t i o n 3 specimens (Table 31), i t was not po s s i b l e t o estimate t h i c k n e s s and moisture content f o r th a t s e c t i o n i n PF IB-337-bonded sugar maple LVL. There was no d i f f e r e n c e between t h i c k n e s s of dry t e s t specimens from s e c t i o n s 1 and 2, and s e c t i o n 1 was l e s s than two percent t h i c k e r than s e c t i o n 2 a f t e r c y c l i c (vacuum/pressure) soak. Moisture content of sections 1 and 2 d i d not d i f f e r s i g n i f i -c a n t l y i r r e s p e c t i v e of, aging. In a l l wood species/aging/glue combinations, except i n b l a c k cottonwood/dry test/PF IB-337, the trend was towards a s l i g h t l y lower t h i c k n e s s i n s e c t i o n 2 than the two other s e c t i o n s which were approximately equal. I f thicknesses d i f f e r e d a p p r e c i a b l y at time of manufacture, they were almost f u l l y recovered a f t e r the c o n d i t i o n i n g . 73 The d i f f e r e n c e s i n t h i c k n e s s and moisture content of sections are not of such magnitude as could a f f e c t continuous LVL adversely i n s e r v i c e . The s t r e n g t h and r e l a t e d c h a r a c t e r i s t i c s considered showed c o n s i s t e n t l y higher v a r i a b i l i t y i n s e c t i o n 3 than i n s e c t i o n s 1 and 2, i r r e s p e c t i v e of aging. There was no c o n s i s t e n t trend between s e c t i o n s 1 and 2 w i t h i n species. White spruce LVL was the most v a r i a b l e i n shear strength and wood f a i l u r e i n s e c tions 1 and 2. Conversely, i t was the l e a s t v a r i a b l e i n s e c t i o n 3. 5.2.2 Strength Q u a l i t y Response to the Continuous Board Laminating Process The average strength c h a r a c t e r i s t i c s discussed above showed the o v e r a l l q u a l i t y of s e c t i o n s without l o c a t i n g i n d i v i d u a l observations as they occurred i n the beam. The object of t h i s q u a l i t y response t e s t was t o examine q u a l i t y of bonds along the length of continuous LVL board. Defects co u l d , t h e r e f o r e , be r e l a t e d t o the continuous LVL produc-t i o n process. 5.2.2.1 G l u e l i n e temperature along l e n g t h of boards Recorder channels (thermocouple p o i n t s i n LVL) I and 2 monitored the temperature of s e c t i o n 1 c e n t r a l and outer g l u e l i n e s r e s p e c t i v e l y , and 5 and 8 monitored those of the l a s t two inches of s e c t i o n 2'. In a l l , except PF IB-337-74 bonded black cottonwood and sugar maple, CGLT at point 8 was s l i g h t l y lower than t h a t at point 1 (see Table 33). A lower temperature at point 8 was expected because of heat l o s s at edge of pl a t e n s , as reported by Carruthers (1959). The temperature r i s e of three c r i t i c a l p o i n t s i n the continuous board i s presented i n f i g u r e 9. P o i n t s 5 and 8 were not c r i t i c a l because t h a t segment of board would be double pressed and hence f u l l cure was assured. P o i n t s 1 and 2 were c r i t i c a l because they would determine the press time. I t was mandatory t o have temperature at p o i n t s 7, 3, 6 and 4 (see fi g u r e - 2 ) as low as p o s s i b l e because that segment might be under substandard pressure. I f soy. at high temperature, glue would precure or dry out and f a i l t o flow or t r a n s f e r . S e c t i o n s f u r t h e r than p o i n t s 6 and 4 would s u f f e r prolonged closed assembly time, and while the glue might not precure, i t would s u f f e r moisture l o s s and hence improper bonding as Troughton and Chow (1972) demonstrated w i t h plywood. Figure 9 shows that up t i l l about 226°F ( i . e . during the f i r s t 15 minutes of press time) CGL of b l a c k cottonwood LVL showed the f a s t e s t r a t e of temperature p i c k up. From then on temperature r i s e was slow. Temperature of c e n t r a l g l u e l i n e , one i n c h outside p l a t e n , was lower t h a n . i t s outer g l u e l i n e e quivalent i n white spruce and sugar maple. The b e t t e r performance of white spruce i n s e c t i o n 3 i s under-standable because i t scored the lowest temperatures at pounts 7, 3, 6 and 4 except f o r PF IB-334 bonded sugar maple 75" which recorded a lower temperature than d i d white spruce LVL at point 4 ( r e f e r to f i g u r e 7 and Table 32). The lower c e n t r a l g l u e l i n e temperature of white spruce LVL suggested temperature to be the main cause of f a i l u r e of s e c t i o n 3. The c e n t r a l g l u e l i n e temperature of bla c k cottonwood was higher i n s e c t i o n 3 than t h a t of sugar maple and the sugar maple LVL s t i l l performed more poorly than d i d black cottonwood LVL. A l s o , temperature i n p o i n t s 7 and 6 were lower i n LVL boards bonded w i t h PF IB-337 than i n those bonded w i t h PF IB-334. Nevertheless, the l a t t e r produced b e t t e r bonds i n s e c t i o n 3. These suggest that f a c t o r s , other than temperature, were re s p o n s i b l e f o r f a i l u r e of s e c t i o n 3. P o r o s i t y of veneers and e f f e c t of a d d i t i v e s i n the glues are probably two of such f a c t o r s . 5.2.2.2 Gr a p h i c a l i l l u s t r a t i o n of bond q u a l i t y of c e n t r a l g l u e l i n e In a l l cases, the most serious s t r e n g t h f a i l u r e occurred at the beginning of s e c t i o n 3. This f u r t h e r suggested that high temperature was more c r i t i c a l than pressure. The l a s t 18 inches of the c e n t r a l g l u e l i n e of s e c t i o n 3 should pass because i t d i d not experience long assembly time. In a l l f i g u r e s except 11 and 13 (wood f a i l u r e of PF IB-337-bonded black cottonwood and same of PF IB-334 b l a c k cottonwood), t h i s l a s t segment was a l s o h i g h l y v a r i a b l e . 76 Figures 16 and 17 showed s i g n i f i c a n t improvement of shear strength and wood f a i l u r e , r e s p e c t i v e l y , of PF IB-334-bonded sugar maple LVL over those of PF IB-337-bonded LVL ( f i g u r e s 14, 15). The same was true of b l a c k cottonwood LVL i n f i g u r e s 10, 11 and 12, 13. This i s probably due to presence of f i l l e r s which reduced dry out. The v a r i a b i l i t y of white spruce LVL i s depicted i n f i g u r e s 18 and 19. While the average f i g u r e s were reason-a b l y high, v a r i a b i l i t y along the length was very h i g h . The f i r s t 12 inches of s e c t i o n 3 a l s o showed d e f i n i t e evidence of some f a i l u r e . The. graphs showed that a l l the continuous LVL boards produced were markedly v a r i a b l e along t h e i r l e n g t h . Even sec t i o n s 1 and 2, which developed high strength values i n the c e n t r a l g l u e l i n e s , were a l s o markedly v a r i a b l e . The shear strength of PF IB-334-glued black cottonwood LVL ( f i g u r e 12) showed a marked drop i n strength along the board from s e c t i o n 1 through s e c t i o n 2. The trend a f t e r c y c l i c (vacuum/pressure) soak showed s e c t i o n 1 f a i r l y uniform and same w i t h s e c t i o n 2 which was a l s o shown to be d e f i n i t e l y lower than s e c t i o n 1. This drop i n strength i s probably due to wood d e t e r i o r a t i o n i n s e c t i o n 2. In the other f i g u r e s , s e c t i o n 2 showed g e n e r a l l y higher average values than s e c t i o n 1. This t e s t proved to be more s e n s i t i v e than the average v a l u e s . Not only are a l l boards shown to be h i g h l y v a r i a b l e , but even white spruce was shown t o have developed 77 weaker bonds at the step j o i n t s which protruded from the press. 5.2.2.3 Delamination t e s t 5.2.2.3.1 C y c l i c vacuum/pressure delamination (CSA 0177-1965) The shear strength t e s t showed the q u a l i t y of the c e n t r a l g l u e l i n e only. The delamination t e s t was t o show the q u a l i t y of a l l g l u e l i n e s . As stated above, the temperatures of the outer g l u e l i n e at p o i n t s 3 and 4 were higher than those of the c e n t r a l g l u e l i n e at p o i n t s 7 and 6, r e s p e c t i v e l y , i n almost a l l cases. This caused the outer g l u e l i n e and the g l u e l i n e between i t and c e n t r a l g l u e l i n e ( h e r e a f t e r c a l l e d mGL) t o be more s u s c e p t i b l e t o dryout or precure than the c e n t r a l g l u e l i n e . Resistance to delamination would t h e r e f o r e be a b e t t e r estimate of bond q u a l i t y of a l l g l u e l i n e s . The average delamination f i g u r e s presented i n Table 33 showed th a t only PF IB-337-bonded sugar maple f a i l e d the maximum 8 percent delamination s p e c i f i e d f o r hardwoods. None of the samples f a i l e d i n s e c t i o n 2 and only sugar maple LVL f a i l e d i n s e c t i o n 3, i r r e s p e c t i v e of glue used. White spruce LVL showed no delamination i n any of the three s e c t i o n s . S e c t i o n 3 of PF IB-337-bonded black cottonwood LVL appeared t o pass the t e s t by s c o r i n g an average of 7 percent delamination. Performance of consecutive specimens 78 showed that only the f i r s t four of the 13 specimens f a i l e d , scoring from 11 t o 34 percent delamination. A l s o i n three cases, some of the delamination occurred i n mGL and i n seven cases, some of the delamination occurred i n c e n t r a l g l u e l i n e . I n PF IB-334 bonded black cottonwood LVL, only the f i r s t two specimens of s e c t i o n 3 f a i l e d , each scoring 32 and 35 percent delamination r e s p e c t i v e l y . Each of the g l u e l i n e s showed some measure of delamination. Sugar maple LVL (PF IB-337-bonded) showed large scale delamination. S i x of the ten specimens i n s e c t i o n 1 f a i l e d , most of the f a i l u r e being a t t r i b u t e d t o larg e knots and very rough spots around knots i n the c e n t r a l g l u e l i n e . Ten of the 15 recorded cases of delamination occurred i n the c e n t r a l g l u e l i n e . Only once d i d delamination occur i n the outer g l u e l i n e , while i t occurred four times i n the mGL. S e c t i o n 2 wa.s r e l a t i v e l y good but two specimens f a i l e d . The f i r s t specimen i n s e c t i o n 3 recorded 55 percent delamination, the next four completely delaminated i n the c e n t r a l g l u e l i n e , the next two scored 30 and 27 percent, r e s p e c t i v e l y , w i t h a l l delamination being i n mGL. The next specimen completely delaminated, and the l a s t four scored 23, 27, 21 and 14 percent, r e s p e c t i v e l y , and most of the delamination occurred i n the CGL followed by CGL. In s e c t i o n s 1 and 2 of PF IB-334-bonded sugar maple, delamination was n e g l i g i b l e . In s e c t i o n 3, there was no complete delamination of any specimen but delamination was 79 high i n the f i r s t part of s e c t i o n 3. The recorded delamin-a t i o n s were 34, 46, 22, 11, 7, 0, 10, 14, 15, 1 4, 0, 0 percent, r e s p e c t i v e l y , beginning from the p l a t e n end of s e c t i o n 3. Eighteen out of the 25 recorded cases of delamination occurred i n mGL, three i n the outer g l u e l i n e and four i n the c e n t r a l g l u e l i n e . These t e s t r e s u l t s showed that the l o c a t i o n of delamination i s more important than the average. Therefore, both black cottonwood and sugar maple LVL ( i r r e s p e c t i v e of glue used) f a i l e d the delamination t e s t . Table 34 shows average b o i l t e s t delaminations f o r b l a c k cottonwood and sugar maple LVL which are lower than f i g u r e s recorded f o r c y c l i c (vacuum/pressure/dry) delamination i n Table 33. In the black cottonwood LVL f i g u r e s , only the f i r s t two specimens f a i l e d i n s e c t i o n 3, scoring 23 and 14 percent delamination, r e s p e c t i v e l y . This shows that the f i r s t four inches of s e c t i o n 3 f a i l e d . Sugar maple LVL showed a more severe f a i l u r e than black cottonwood LVL but i n both cases f a i l u r e was r e l a t i v e l y l e s s severe than i n the c y c l i c vacuum/pressure/dry delamination. These agreed w i t h the f i n d i n g of F i s c h e r and Bensend (1969) t h a t the b o i l t e s t i s a l e s s s e n s i t i v e t e s t of bond q u a l i t y . T h i s i s due t o the tendency of b o i l t e s t to complete c u r i n g of undercured bonds which the vacuum/pressure t e s t would d e t e c t . F a i l u r e of s e c t i o n 3 of the LVL board makes the continuous LVL production process, described by Bohlen (1972a) 80 and modified f o r species studied i n t h i s t h e s i s , not t e c h n i c a l l y f e a s i b l e . The process was q u i t e adequate f o r white spruce, though f u r t h e r work i s required t o reduce the v a r i a b i l i t y of white spruce LVL beams. A p o s s i b i l i t y f o r hardwoods i s to use a c o o l i n g system ( e i t h e r a water j a c k e t or dry i c e ) around the stepped j o i n t s protruding from the platens to minimize the temperature r i s e of t h i s s e c t i o n of board. Development of glues w i t h b e t t e r assembly time tolerance would represent a major breakthrough i n the development of t h i s wood product. The small panels had proved that adequate bonds could be produced w i t h these s p e c i e s . Beams up to or longer than 16 f e e t could be produced, using 16-foot p l a t e n (or longer) presses. In such a case, a beam l i k e t hat shown i n f i g u r e 3 could be assembled and pressed i n one press c y c l e . Such a beam would ensure a l l the advantages of u n i f o r m i t y of moisture content and strength, c h a r a c t e r i s t i c of laminated beams. M u l t i p l a t e n arrange-ments are a l s o p o s s i b l e which would increase d a i l y production and minimize u n i t c o s t . Such m u l t i p l a t e n arrangements would involve some mechanized layup, charging and d i s c h a r g i n g of press. An 8-opening 16-foot p l a t e n press c u r r e n t l y c o s t s about $250,000.00 and would represent the main item of cost i n an operation coupled t o a l a r g e r m i l l complex. A l i s t i n g and current cost of the machinery f o r an independent operation i s presented i n appendix An economic a n a l y s i s of such a production operation i outside the scope of t h i s t h e s i s . 82 6.0 CONCLUSION Veneers used i n t h i s study were obtained from wood species grown i n Canada. Trees were not obtained by any s p e c i a l sampling design, and b o l t s were fre e only of sound and unsound de f e c t s that would s e r i o u s l y hinder p e e l i n g . R e s u l t s do not, t h e r e f o r e , n e c e s s a r i l y r e f l e c t the c h a r a c t e r i s t i c s of the species as a whole. Conclu-sions based on stated experiments, sample s i z e s and observations of sample behaviour can, however, be drawn. A simple experimental design that would i n c o r p o r -ate a l l p o s s i b l e treatment combinations was not considered f e a s i b l e because of incomplete i n f o r m a t i o n on glue cure, heat p e n e t r a t i o n of wood species a v a i l a b l e , and optimum press schedules f o r the wood product under t e s t . E x p e r i -ments were t h e r e f o r e conducted s u c c e s s i v e l y , and f a c t o r s which were not considered u s e f u l from a production point of view were e l i m i n a t e d . Some of the f a c t o r s not t e s t e d , such as lower gluespreads f o r black cottonwood LVL at 100 p s i , and f o r sugar maple LVL at 275 p s i and glue PF IB-334 f o r optimum gluespread, could f u r n i s h u s e f u l i n f o r m a t i o n i n a more extensive p r o j e c t . Presence of glue decreased r a t e of temperature r i s e of the c e n t r a l g l u e l i n e , i n a l l species t e s t e d and t h i s e f f e c t was p r o p o r t i o n a l t o gluespread. When using p l a t e n 83 temperature of 350°F and gluespread of 42.5 lb/MSGL, press times of 19, 20 and 22 minutes were found s u i t a b l e f o r continuous LVL of white spruce, sugar maple and black cottonwood, r e s p e c t i v e l y . G l u e l i n e shear strength and wood f a i l u r e increased w i t h i n c r e a s i n g gluespread and pressure i n broadleaf maple, black cottonwood and sugar maple LVL. The c e n t r a l g l u e l i n e temperature a t t a i n e d , and not the p l a t e n temperature used t o a t t a i n i t , was the main f a c t o r t h a t determined c e n t r a l g l u e l i n e bond q u a l i t y . There was no s i g n i f i c a n t d i f f e r e n c e between c e n t r a l g l u e l i n e strength q u a l i t y of broadleaf maple LVL produced at a c e n t r a l g l u e l i n e temperature of 240°F and tha t produced at 300°F. Small LVL panels.produced at a gluespread of 42.5 lb/MSGL, c e n t r a l g l u e l i n e temperature of 240°F, and pressures of 200 p s i , f o r broadleaf maple; 275 p s i f o r sugar maple; and 100 p s i f o r black cottonwood, produced wood f a i l u r e s which passed the American N a t i o n a l Standards s p e c i f i c a t i o n P.S. 56-73. Small sugar maple LVL panels, constructed t o simulate the double pressing which occurs i n continuous LVL production, showed no s i g n i f i c a n t d i f f e r e n c e s i n t h i c k n e s s between single-pressed and double-pressed panels, but a s i g n i f i c a n t d i f f e r e n c e i n moisture contents. There was a s i g n i f i c a n t r e d u c t i o n i n strength of double-pressed phenol-formaldehyde glue IB-337-bonded LVK, but a s i g n i f i c a n t 84 increase i n strength of that bonded w i t h the same glue modified f o r dry-out r e s i s t a n c e . There was considerable v a r i a t i o n between the three s e c t i o n s w i t h i n the continuous LVL boards i n a l l species considered. The average strength values of s e c t i o n s , the strength q u a l i t y response p l o t t e d i n t o graphs and the delamination t e s t s showed th a t the step j o i n t s which protruded from platens during a press c y c l e i n both b l a c k cottonwood and sugar maple continuous LVL f a i l e d . There-for e the species would be unsu i t a b l e f o r continuous LVL production w i t h the manufacturing process described by Bohlen (1972a) and modified i n t h i s study. The phenol-formaldehyde glue modified f o r dry-out r e s i s t a n c e (IB-334) produced b e t t e r bonds i n the step j o i n t s than d i d the unmodified PF IB-337 which was o r i g i n -a l l y formulated f o r D o u g l a s - f i r LVL. White spruce produced LVL of reasonable q u a l i t y but would re q u i r e f u r t h e r and more d e t a i l e d study t o minimize the v a r i a b i l i t y w i t h i n the board. P h e n o l - r e s o r c i n o l glue produced stronger and l e s s v a r i a b l e bonds than d i d phenol-formaldehyde glues i n sugar maple and black cottonwood LVL. 85 7.0 RECOMMENDA HONS The main features of the continuous LVL production process are: u t i l i z a t i o n of conventional plywood machinery, o p e r a t i o n a l s i m p l i c i t y , labour intensiveness and the many advantages of wide endless boards. I recommend: ( l ) the use of a c o o l i n g system f o r the step j o i n t s , coupled w i t h f o r m u l a t i o n of a b e t t e r adhesive or (2) the use of a s i n g l e -step system employing a long press i n order t o extend the p o t e n t i a l of t h i s wood product t o the u t i l i z a t i o n of hard-woods. 86 8o0 LITERATURE CITED American N a t i o n a l Standards. 1973. " S t r u c t u r a l Glued laminated timber v o l u n t a r y product standard P.S. 56-73." American N a t i o n a l Standard A 190, 1-1973. Arneson, G.N. 1947. 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E f f e c t of thic k n e s s of g l u e l i n e on strength and d u r a b i l i t y of glued wood j o i s t s . USDA Forest Serv. Rept. No.: R1616, US FPL Madison, Wis. C u r r i e r , R.A., 1960. Compression of white pocket veneer i n hot-pressed D o u g l a s - f i r plywood. F o r e s t r Prod. J . 10(8): 409-415. Curry , W.J. 1957. The strength p r o p e r t i e s of plywood Part 3: Influence of the adhesive. DSIR, Forest Prod. Res. B u l l . No. 39, HMSO, London. Dobie, J . , 1970. Trends i n Forest research use and f o r e s t products manufacturing i n B r i t i s h Columbia, Canada Forest Serv. Western Forest Prod. Lab. I n f o . Rept. VP-X-75. 9 pp. Echols, R.M., and R. A. C u r r i e r , 1973. Comparative proper-t i e s of D o u g l a s - f i r boards made from p a r a l l e l - l a m i n -ated veneers vs s o l i d wood. Forest Prod. J . 23(2): 45-47. Eickner, H.W. 1942. The g l u i n g c h a r a c t e r i s t i c s of 15 species of wood w i t h c o l d s e t t i n g u r e a - r e s i n glues. USDA Forest Serv. Mimeo No. 1342. Forest Prod. Lab., Madison, Wis. Enabor, E.E. 1973. The prospects of f o r e s t i n d u s t r i e s development i n N i g e r i a . Journal of the Geographical A s s o c i a t i o n of N i g e r i a 16.(1) : 51-65. Farmer, R.H. (ed.) 1972. Handbook of hardwoods, 2nd ed. Buiding Research Establishment. P r i n c e s Risborough Forest Prod. Lab. Aylesbury, Buckinghamshire. F e i h l , 0. 1960. Wear, play and heat d i s t o r t i o n i n veneer l a t h e s . Canadian Wood Worker. Dec. 1960. and V. Godin, 1970. P e e l i n g d e f e c t s i n veneer, t h e i r causes and c o n t r o l . Canada Dept. Fo r e s t . R u r a l Develop. Publ. No. 1280. , 1966. Veneer and plywood from aspen poplar. Canada Dept. Fo r e s t . R u r a l Develop. Publ. No. 1157. F i s c h e r , C., and D. W. Bensend. 1969. G l u i n g of southern pine veneer w i t h blood modified phenolic r e s i n g lues. Forest Prod. J . 19_(5): 32-37. 8 9 Freeman, H.A. 1959. R e l a t i o n between p h y s i c a l and chemical p r o p e r t i e s of wood and adhesion. Forest Prod. J . 2(12): 451-458. F r i t z , D.W. 1969. The p h o t o e l a s t i c coating method a p p l i e d to s t r e s s a n a l y s i s of wood. Master's degree t h e s i s , Oregon State Univ. C o r v a l i s ( o r i g i n a l not seen, c i t e d from Bohlen, 1972a). Government of B.C. 1972. The sawmilling i n d u s t r y of B r i t i s h Columbia. Dept. Ind. Develop. Trade and Comm. Parliament B u i l d i n g s , V i c t o r i a , B.C. Hann, R.A., R.W. J o k e r s t , R.S. Kurtenacker, C.C. Peters, and J . L. T s c h e r n i t z , 1971. Rapid production of p a l l e t deckboards from low-grade l o g s . USDA Forest Prod. Lab. Madison, Wis. Hse, C.V. 1968. G l u a b i l i t y of Southern pine e a r l y wood and l a t e wood. Forest Prod. J . 18_(l2): 32-36. J a r v i , R.A. 1967. E x t e r i o r glues f o r plywood. Forest Prod. J . 17(1): 37-42. J o k e r s t , R.W. 1972. F e a s i b i l i t y of producing a h i g h - y i e l d laminated s t r u c t u r a l product: r e s i d u a l heat of dry i n g a c c e l e r a t e s adhesives cure. USDA Forest Serv. Res. Pap. FPL179 Forest Prod. Lab. Madison, Wis. Kennedy, E.I. 1965. Strength and r e l a t e d p r o p e r t i e s of woods grown i n Canada. Canada Dept. Forest R u r a l Develop. Publ. No. 1104. Koch, P. 1973. S t r u c t u r a l lumber laminated from ^ - i n c h of uniform high s t r e n g t h . Forest Prod. J . 18(10): 45-51. , 1967. Super-strength beams laminated from r o t a r y cut Southern pine veneer. Forest Prod. J . 1 Z(6): 42-48. , 1964. Techniques f o r drying t h i c k southern pine veneer. Forest Prod. J . 14_(9): 382-386. , and G. W. Woodson, 1968. Laminating b u t t - j o i n t e d log-run Southern pine veneers i n t o long beams of uniform high strength. Forest Prod. J . 18.(10): 45-51. , and B. Bohannan, 1965. Beam streng t h as a f f e c t e d by placement of laminae. Forest Prod. J . 15(7): 289-295. 90 L e i c e s t e r , R.H., and P.C. Bunker, 1969. Fracture at butt j o i n t s i n laminated pine. Forest Prod. J . 19(2): 59-60. L u t z , J.F. 1972. Veneer species t h a t grow i n the United S t a t e s . USDA Forest Serv. Res. Pap. FPL 167, Forest Prod. Lab. Madison, Wis. Luxford, R.F., 1944. Strength of glued laminated S i t k a spruce made up of r o t a r y cut veneer. USDA Forest Serv. Rept. No. 1512, Forest Prod. Lab., Madison, Wis. Macdonald, M.D. 1951. Compression of D o u g l a s - f i r veneer during processing. The Timberman 52.(4) : 98-100; 52.(5): 86-92. MacLean, J.D. 1955. The rat e of temperature change i n wood panels heated between hot p l a t e s . USDA Forest Serv. Rept. No. 1299, Forest Prod. Lab. Madison, Wis. , 1943. . Method of computing the r a t e of temperature change i n wood and plywood panels when the two opposite surfaces are maintained at d i f f e r e n t temperature. USDA Forest Serv. Mimeo No. R1406, Forest Prod. Lab. Madison, Wis. , 1941. Thermal c o n d u c t i v i t y of wood. Reprinted from ASHVE, Journal S e c t i o n , Heating P i p i n g and A i r C o n d i t i o n i n g . , 1932. Studies of heat conduction i n wood - Part I I . R e s u l t s of steaming green sawed southern pine timbers. Proc. AWPA, 1932, pp. 303-329. , 1930. Studies of heat conduction i n wood. R e s u l t s of steaming green round southern pine timbers. Proc. AWPA, 1930, pp. 197-217. Marian, J.E., and D.A. Stumbo, 1962. Adhesion i n wood. P h y s i c a l F a c t o r s . H o l z f o r s c hung 16(5): 134-142. and C.W. Maxey, 1958. Surface t e x t u r e of wood as r e l a t e d t o glue j o i n t strength. Forest Prod. J . 8(12): 345-351. Marra, G.G., 1959. Development of a method f o r r a p i d lamin-a t i n g of lumber without the use of high frequency heat. Forest Prod. J . 6(3): 97-104. 91 McKean, H.B. and W. J . Smith, 1958. P i l o t p l a n t i n g laminated 2 by 4's. Forest Prod. J . 8_(8) : 19A-22A. Moody, R.C., 1972. T e n s i l e strength of lumber laminated from l / 8 - i n c h - t h i c k veneers. USDA Forest Serv. Res. Pap. FDL 181 Forest Prod. Lab. Madison, Wis. , and C.C. Peters. 1972. F e a s i b i l i t y of producing of high y i e l d laminated s t r u c t u r a l product: strength property of r o t a r y k n i f e cut laminated southern pine. USDA Forest Serv. Res. Pap. FDL 178, Forest Prod. Lab. Madison, Wis. Murphey, W.K., 1963. C e l l w a l l c r y s t a l l i n i t y as a f u n c t i o n of t e n s i l e s t r a i n . Forest Prod. J . I3_(l4) : 151-155. N o r t h c o t t , P.L., 1955. Bond strength as i n d i c a t e d by wood f a i l u r e or mechanical t e s t . Forest Prod. J . 5(2): 118-123. ., and D.C. Walser., 1965. Veneer roughness s c a l e . Canada Dept. F o r e s t . Rural Develop. Forest Prod. Res. C o n t r i b . No. P-115, 3 pp. W.V. Hancock and H.G.M. Colbeck, 1963. Evidence o f heed f o r wood f a i l u r e , standard. Adhesion S.T.P. No. 360 of the ASTM. 13,pp. , and H.G.M. Colbeck, 1960. P r e d i c t i o n of plywood bond d u r a b i l i t y . Forest Prod. J . 1 0 . ( 8 ) : 403-408. W.V. Hancock, and K.C. Shen. 1959. Undercure... case hardening i n plywood. Forest Prod. J . 9.(12): 442-450. Olson, W.Z., and R.J. Blomquist, 1953. G l u i n g techniques f o r beech. Beech u t i l i z a t i o n s e r i e s No. 5. North Eastern Technical Committee on the u t i l i z a t i o n of beech, i n co-operation w i t h North Eastern Forest Experiment S t a t i o n , USDA, Forest Serv. Orth, G.O., and A . J . Norton, 1947. Personnel f a c t o r s i n high frequency g l u i n g . Proc. Conf. Radio Frequency and i t s A p p l i c a t i o n s i n Gluing Wood. Univ. of Washington, S e a t t l e , Wash. B u l l . No. 2, pp. 21-23. Pa l k a , L.C., 1964. Factors i n f l u e n c i n g the streng t h p r o p e r t i e s of D o u g l a s - f i r plywood normal t o g l u e l i n e . M.F. t h e s i s , F a c u l t y of F o r e s t r y , U n i v e r s i t y of B r i t i s h Columbia. 92 Parker, R.S.R., and P. T a y l o r , 1966. Adhesion and adhesives. Pergamom Press Inc. 44-01 21st s t r e e t , Long I s l a n d C i t y , New York 11101. P e r k i t n y , T., and L. H e l i n s k a , 1961. Uber den E i n f l u s s g l o i c h z e i t i g e r , Temperatur-und Feuchtigkctsanderung auf die Verformungen des Holzes. Holz a l s Roh Werkstoff 19(7): 259-269. ( c i t e d from P a l k a , 1964) Sc h a f f e r , E.L., J o k e r s t , R.W., R.C. Moody, C C . Pe t e r s , J.L. T s c h e r n i t z , and J . J . Zahn., 1972. F e a s i b i l i t y of producing a h i g h - y i e l d laminated s t r u c t u r a l product: General summary. USDA Forest Serv. Res. Pap. FPL 175, Forest Prod. Lab. Madison, Wis. Shelton, F.J., 1969. Plywood adheasives—developments and tre n d s . Forest Prod. J . 1 9 ( l ) : 9-12. Stumbo, D.A. 1960. Surface t e x t u r e measurements f o r q u a l i t y and production c o n t r o l . Forest Prod. J . 10(2): 122-124. Troughton, G.E., and S.-Z. Chow, 1972. A study on the cause f o r v a r i a t i o n i n plywood bond q u a l i t y w i t h open assembly time. Forest Prod. J . 22.(3): 55-58. Truax, T.R. 1929. The g l u i n g of wood. USDA Forest Serv. Tech. B u l l . No. 1500. Forest Prod. Lab. Madison, Wis, ( o r i g i n a l not seen, c i t e d from Olson and Blomquist 1953J. USDA Forest S e r v i c e , 1955. Wood handbook. A g r i c . Handbk. 72, Forest Prod. Lab. Madison, Wis. US Forest Products Laboratory, 1966. Basic p r o p e r t i e s of y e l l o w - b i r c h laminates modified w i t h phenol and urea r e s i n s . U.S. Forest Serv. Res. Note FPL-0140 ( o r i g i n a l not seen, c i t e d from Moody, 1972). , and Gamble Brothers, Inc. 1944. Manual on the laminat i n g of r e s i n glues. USDA Forest Prod. Serv. Mimeo No. R1437, Forest Prod. Lab. Madison, Wis. Westman, E.F., and L . J . Nemeth., 1968. S i n g l e p l y vs. 2-ply laminated t e n s i o n v a l u e s . Forest Prod. J . 18(8) 41-42. Winlund, . 1947. High frequency g l u i n g - f a c t or fantasy. Proc. Conf. on Radio Frequency and i t s A p p l i c a t i o n i n G l u i n g Wood. Coll e g e of F o r e s t r y , Univ. of Washington, S e a t t l e , Wash. B u l l . No. 2, pp. 6-17. 93 Wood, A.D., 1963. Plywoods of the world, t h e i r development manufacture and a p p l i c a t i o n . W & A.K. Johnson and G.W. Bacon, L t d . Edinburgh and London, 489 pp. Zisman, W.A., 1963. Influence of c o n s t i t u t i o n on adhesion. Ind. and Eng. Chem. 5_5_(l0): 19-38. 94 ' 9.0 TABLES 95 TABLE 1 Frequency of grades of black cottonwood ^ - i n c h veneers peeled f o r the study G R A D E S ^ Veneer s i z e A BB B C C- T o t a l F R E Q U E N C Y F u l l s i z e 1 8 18 20 17 64 Narrows 5 15 2 22 F i s h t a i l s 4 2 - 6 T o t a l 10 8 35 22 17 92 According to CSA standard 0153-1963 f o r popular plywood veneers. F u l l s i z e i s 25 by 54 inches. Narrows are from seven to 15 inches wide by 54 inches. F i s h t a i l s are from f i v e t o ten inches wide by 20 to 39 inches long. 96 TABLE 2 Average green moisture content of black cottonwood 'A i n c h veneers ^ b c B o l t No, Sapwood Heartwood B o l t average 1 178.5 164.4 171.4 2 190.9 212.7 201.8 3 160.6 144.2 152.4 4 210.4 143.0 176.7 A l l b o l t s average 185.1 166.1 176 c a Veneers were wrapped i n polythene p l a s t i c sheets, a f t e r about f i v e minutes exposure, to check (minimize) moisture c o n t r o l . b Each woodzone f i g u r e i s an average of three moisture content values. Rounded to the nearest one percent moisture content. TABLE 3 Design of s m a l l - p a n o l experiments Veneer Wood Spe c i e s Test V a r i a b l e Experiment Design A n a l y s i s B r o a d l e a f Maple Adequate 2 Gluespread Maximum f a i l -i n g l o a d i n shear ( l b ) Shear st r e n g t h ) ( p s i ) Wood f a i l u r e (*) 4 x 2 F a c t o r i a l (crossed) i Completely randomized i i L i n e a r model 3 i s Y i j k = ^ + S i + A j + ( S A ) i j + E i j k -ANOVA -1 w i t h i n t e r -a c t i o n s 1 Maximum f a i l - ) i n g l o a d i n shear ( l b ) E f f e c t of ) 2 x 2 p l a t e n 2 Shear s t r e n g t h ) F a c t o r i a l temperature ( p s i ) ) (crossed) 3 Wood f a i l u r e {%) i C ompletely randomized i i L i n e a r model'5 i s Y i j k = f + P i + A j + ( P A ) i j + E i j k — 2 Adequate '. c u r i n g temperature Maximum f a i l -i n g l o a d i n shear ( l b ) 3 x 3 Shear s t r e n g t h ) F a c t o r i a l ( p s i ) } (crossed) Wood f a i l u r e (%)  i C o m p l etely randomized i i L i n e a r model 0 i s Y i j k = ^ + C i + A j + ( C A ) i j + E i j k — - 3 E f f e c t of p l a t e n p r e s s u r e 1 Maximum f a i l - ) i n g l o a d i n shear ( l b ) 2 Shear s t r e n g t h ) ( p s i ) 3 Wood f a i l u r e Mean and standard d e v i a -t i o n B l a c k Adequate 3 Cottonwood gluespread and Sugar Maple 2 Shear s t r e n g t h ) ( p s i ) Wood f a i l u r e [%) 3 x 2 F a c t o r i a l i Completely ANOVA randomized , w i t h i i L i n e a r model i s same as i n t e r -i n e q u a t i o n 1 a c t i o n s Adjusted shear) S i n g l e s t r e n g t h ( p s i ) ) f a c t o r i C ompletely randomized i i L i n e a r model i s Yijk=/<+Sj+Eij One-way ANOVA 1 Shear s t r e n g t h ) i C o m p l e t ely ANOVA ( p s i ) ) 2 x 2 randomized w i t h F a c t o r i a l i i L i n e a r model i s same i n t e r -II Adequate pre s s u r e 3 Wood f a i l u r e ) (*) ) (crossed) as i n e q u a t i o n 2 a c t i o n s 2 Ad j u s t e d shear) s t r e n g t h ( p s i ) ) S i n g l e f a c t o r i i i C o m pletely randomized j: L i n e a r model i s same i n e q u a t i o n 4 One-way ANOVA as Sugar Maple E f f e c t of double p r e s s i n g 1 Shear s t r e n g t h ) ( p s i ) 3 Wood f a i l u r e [%) 4 LVL t h i c k n e s s ( i n ) 5 Moisture con-t e n t (%) 2 Adjusted shear) s t r e n g t h ( p s i ) ) 2 x 2 F a c t o r i a l (crossed) i Completely .,,„,,„ randomized w i t h i i L i n e a r model^ i s i n t e r -Yijk=y[/ +Pi+Gj+(PG)ij+£ijk—5 a c t i o n s S i n g l e f a c t o r i C o m pletely randomized One-i i L i n e a r model" same as .'!,." i n e q u a t i o n 5  •way ANOVA Adequate gluespread w i t h modif i e d phenol-r e s o r c i n o l glue(MPKG) 1 Shear st r e n g t h ) ( p s i ) ) 3 Wood f a i l u r e ( 2 x 2 F a c t o r i a l ( c r o s s e d ) 2 Adjusted shear) S i n g l e s t r e n g t h ( p s i ) ) f a c t o r i Completely randomized ANOVA i i L i n e a r model* i s the w i t h samek as i n e q u a t i o n 1 i n t e r -a c t i o n s i Completely randomized One-way i i L i n e a r moduli i s _ t h o ANOVA same as i n eq u a t i o n 4 Bla c k Cottonwood Bond q u n l l t y w i . L h IVIPKG 1 Shear st r e n g t h ) ( p s i ) 2 Wood f a i l u r e ( CO ' S i n g l e f a c t o r i Completely randomized One-way i i L i n e a r model1'- i s same ANOVA an i n e q u a t i o n 4 9 8 •TABLE 3 - Continued a In equation 1, S = gluespread, A = aging, i . e . dry or c y c l i c (vacuum/pressure) soak; E = e r r o r ; i = 1,2,3,4; j = 1,2; k = 1,2 10 b In equation 2, P = p l a t e n temperature; A = aging; E = e r r o r , and i = 1,2; j - 1,2, and k = 1,2 - - - 15. c In equation 3, C = c e n t r a l g l u e l i n e temperature; A = aging; E = e r r o r ; i = 1,2,3; j = 1,2,3, and k = 1, 2, 15. d Model n o t a t i o n i s the same as f o r equation 1, but i = 1,2,3 and k = 1,2, - - - 15. e In equation 4. S = e f f e c t of the j t h treatment ( i . e . gluespread by dry t e s t ) , E = e r r o r ; j = 1,2.3 (treatments); i = 1,2 - - - 15 (observations per treatment). f Model n o t a t i o n i s the same as i n equation 2, except t h a t P = p l a t e n pressure, and k = 1,2 - - - 15. 9 Model n o t a t i o n i s the same as i n equation 4, except that S = pressure by dry t e s t and j = 1,2. h In equation 5, G = glue type (PF IB-337 or PF IB-334); P = press time, E = e r r o r ; j = 1,2; i = 1,2, and k = 1,2 15. i Model n o t a t i o n i s the same as i n equation 4, except t h a t S = glue type by dry t e s t , and j = 1,2. 3 Model n o t a t i o n i s the same as i n equation 1, except t h a t i = 1,2 and k = 1,2 15. Model n o t a t i o n i s same as i n equation 4, except t h a t j = 1,2. '''Model n o t a t i o n i s same as i n equation 4, except t h a t S i s e f f e c t of aging on the i t h observation. > TABU; A Factors examined i n tho small panel experiments 99 Veneer wood F A C T 0 I! species Test A c omme nt . D Comment Gluespread Aging 1 27.5 lb/MSGL) chor.en to 1 Dry (laboratory (Kecommended Broadleaf Adequate 2 30 " " ) cover plywood condition) (by Bohlen for maple gluespread 3 37.5 " " ) and LVL manu- 2 24-hour cold (LVL 4 42.5 " " ) facturing soak practice Platen Aging Temperature n Effect of 1 300°F) two extremes 1 Dry ( laboratory platen 2 400°F) chosen condit ion) II temperature a r b i t r a r i l y 2 24-hour cold soak Central g lue l ine Temperature3 Adequate 1 233°F) curing ) temperature 2 240°F] 3 300°F) curing range of many phenolic glues Aging 1 Dry ( labora-tory condit ion) 2 24-hour cold soak 3 C y c l i c (vacuum/ pressure) soak , modified test ,for q u a l i t y of , centra l glue-, l i n e bond Black cotton-wood Adequate gluespread Gluespread 1 30 lb/MSGL chosen to cover plywood 2 37.5 lb/MSGL and LVL manu ) factur ing 3 42.5 lb/MSGL) practice Aging 1 Dry ( laboratory condit ion) 2 C y c l i c (vacuum/ pressure) soak (modified test (for q u a l i t y (of c e n t r a l (g lue l ine bond Platen pressure Aging It Adequate 1 69 p s i ) w i t h i n range 1 Dry (laboratory pressure 2 100 p s i j speci f ied for condit ion) low density hardwoods 2 C y c l i c (vacuum/ P.S. 56-73 b pressure) soak n Sugar maple Adequate pressure Platen pressure 1 250 p s i 2 275 p s i upper l i m i t 1 recommended for dense hardwoods'3 Aging Dry (laboratory condit ion) ) t r i e d because 2 C y c l i c (vacuum/ i t s w i t h i n pressure) soak ranges reported i n l i t e r a t u r e Pressing time Glue type 1 PF IB-337 C Effect of 1 single ) to simulate double- (20 minutes) ) Bohlen 1 s pressing ) LVL produc- 2 PF IB-334 d 2 double ) t i o n process (40 minutes) ) (to observe (effect of (glue formula-( t i o n Adequate gluespread with MP FIG Gluespread 1 37.5 lb/MSGL Aging lower spreads • r a p i d l y 1 Dry ( laboratory 2 42.5 lb/MSGL j i n t T ^ condit ion) veneers 2 C y c l i c (vacuum/ pressure) soak m e a s u r e d . T e ' : ' P e r a t U r e a t t a i n e d i n P«6s. Rise i n temperature during hot stacking was not "American nat ional Standards, Voluntary Products Standards P.S. 56-1965. c Phenol ic r e s i n glue manufactured by Heichhold Chemicals (Canada) L i m i t e d . d Phenol lc r e s i n glue modified for dryout tolerance (also a Heichhold product) . TABLE 5 Some c h a r a c t e r i s t i c s of the ^ - i n c h veneers used i n t h i s study Veneer Glue to Moisture S p e c i f i c Veneer % depth Veneer Test wood be used content g r a v i t y 3 t h i c k n e s s of l a t e roughness species i n t e s t (%) ( i n ) check ( i n x v 10-3) Mean SD b Mean SD Mean SD Mean SD Mean SD Small ~" . Sugar maple IB-337 3.5 0.02 0.652 0.0016 0.265 0.005 53 10 15 6 panel Black II cottonwood II 5.1 0.02 0.375 0.0016 0.268 0.009 65 19 20 9 Continuous Sugar maple ti 3.4 0.03 0.662 0.0040 0.264 0.005 55 10 15 6 LVL it II II IB-334 3.5 0.02 0.656 0.0015 0.267 0.013 52 12 15 6 II Black c 4 — - < cottonwood IB-337 5.3 0.02 0.370 0.0024 0.268 0.009 72 22 15 7 it II II IB-334 5.2 0.02 0.369 0.0023 0.269 0.010 66 20 20 8 II White spruce IB-337 6.8 0.03 0.376 0.0120 0.268 0.012 30 19 20 7 S p e c i f i c g r a v i t y based on oven dry weight and t e s t volume Standard d e v i a t i o n . 101 TABLE 6 Shear block samples for the small panel t e s t s T E S T A G I N G Drv Coldsoak C y c l i c (Vac/ Dress) soak To t a l Broadleaf Maple Adequate gluespread 5/spread of 42.5 lb/MSGL 10 spread of 27.5, 30 & 37.5 lb/MSGL 5/spread of 42.5 lb/MSGL , 10/spread of 27.5, 30 8. 37.5 lb/MSGL -10 60 E f f e c t of platen temperature 5/platen temperature 5/platen temperature - 20 Adequate curing temperature 5/CGL temperature 5/CGL temperature 5/CGL temperature 45 Other pressures (250 and 275 psi) 5/pressure 5/pressure 10 pressure 40 Black Cottonwood Adequate gluespread 15/spread - 15/spread 90 Adequate pressure 15/aging - 15/aging 60 Suaar Maple Adequate gluespread 15/spread - 15/spread 90 Adequate pressure 15/pressure - 15/pressure 60 E f f e c t of presstime 15/presstime - 15/presstime 60 Adequate gluespread of MPRG glue on sugar maple 15/spread - 15/spread 60 Testing black cottonwood forMPRG glue bond strength 15 - 15 30 TABLE 7 C e n t r a l g l u e l i n e temperature r i s e of phenolic glue IB-337 bonded broadleaf maple LVL Press s i z e Small (16 in . x 16 in) Small (16 i n . x 16 in) Large (54 i n . x 54 i n ) P l a t e n temperature (°F) 300 400 350 Gluespread 1 (lb/MSGL) 0 0 3.0- 37..5 42.5 42.5 0-; 0- 42.5^  42. 5 42.5 42.5 42.5 I n i t i a l c e n t r a l g l u e -l i n e temperaturear(°F) 75 75 75 75 75 75 75 75 75 75 75 97 75 F i n a l temperature of c e n t r a l g l u e l i n e (°F) 233 240 233 233 233 240 233 240 233 240 300 297 240 Time to f i n a l temp-erature (min.) 26 34 32 33 36 40 20 24 27 30 48 39 25 T o t a l temperature change (°F) 158 165 158 158 158 165 158 165 158 165 225 200 165 Factor X b •. °F/min.) 6-1 4 - 9 4 ' 9 4 - 8 4 ' 4 4 - X 7.9 6.9 5.9 5.5 4.7 5.1 6.6 G l u e l i n e was held.at 200"psi platen pressure, and each LVL-panel was 12 inches 0 by 12 inches. . . w Factor X was c a l c u l a t e d by d i v i d i n g change i n CGLT by time of change. 103 TAtU . l i a G l u e l i n e t e m p e r a t u r e i n 6 - p l y L a m i n a t e d - V o n e e r - I . u m b e r a t v a r i o u s l e v e l s o f g l u e s p r e a d S p e c i e s P l a t e n p r e s s u r e I p s i ) G l u e -s p r e a d (W M S G L ) G l u e -l i n e 1 n i t i a 1 t e m p e r a t u r e ( ° l - ' i n a l t e m p e r a -I : r t u r e (°i\ T o t a l . c h a n g e ) i n t e m p -e r a t u r e liiiio t o f i n a l t e m p e r a -t u r e ( m i n ) F a c t o r ( ° 1 : m i n ) P h e n o l -f o r m a l -d e h y d e g l u e -b r a n d C o t t o n -w o o d d 0 C G L 7 8 2 4 1 1 6 3 1 8 9 . 0 6 S a p w o o d b 9 G 0 O G L 9 8 2 9 5 1 9 7 1 8 1 0 . 9 4 -0 C G L 7 7 2 4 0 1 6 3 1 5 . 2 5 1 0 . 6 9 H e a r t w o o d 6 9 0 C G L 1 0 5 2 8 8 1 8 3 1 5 . 2 5 1 2 . 0 0 -3 0 C G L 7 7 2 4 0 1 6 3 2 7 . 5 5 . 9 3 I B - 3 3 7 R a n d o m 6 9 3 0 O G L 8 1 2 9 9 2 1 8 2 7 . 5 7 . 9 3 II 3 7 . 5 C G L 7 8 2 4 0 1 6 2 3 1 5 . 2 3 II it 6 9 3 7 . 5 O G L 8 2 3 0 0 2 1 8 3 1 7 . 0 3 II 4 2 . 5 C G L 7 8 2 4 0 1 6 2 3 5 4 . 6 3 „ n 6 9 4 2 . 5 O G L 8 3 3 0 9 2 2 6 3 5 6 . 4 6 II M 1 0 0 4 2 . 5 C G L 7 7 2 4 0 1 6 3 3 5 4 . 6 6 II 0 7 8 2 4 0 1 6 2 . 1 7 . 3 3 9 . 3 5 I B - 3 3 7 S u g a r 2 5 0 m a p l e 0 O G L 9 9 2 9 9 2 0 0 1 7 . 3 3 1 1 . 5 4 It 3 0 C G L 7 8 2 4 0 1 6 2 1 9 8 . 5 3 II t i 2 5 0 3 0 O G L 8 5 2 9 8 2 1 4 1 9 1 1 . 2 6 II 3 7 . 5 C G L 7 5 2 4 0 1 6 5 2 0 8 . 2 5 n it 2 5 0 3 7 . 5 O G L 8 2 2 9 5 2 1 3 2 0 1 0 . 6 5 it 4 2 . 5 C G L 7 9 2 4 0 1 6 1 2 0 . 2 5 7 . 9 5 II n 2 5 0 4 2 . 5 O G L 8 4 2 9 7 2 1 3 2 0 . 2 5 1 0 . 5 2 n 4 2 . 5 C G L 7 6 2 4 0 1 6 4 1 9 8 . 6 3 II n 2 7 5 4 2 . 5 O G L 8 0 . 2 9 5 2 1 5 1 9 1 1 . 3 2 " 4 2 . 5 C G L 7 5 2 4 0 1 6 5 2 0 8 . 2 5 I B - 3 3 4 tt 2 7 5 4 2 . 5 O G L 7 6 2 8 9 2 1 3 2 0 1 0 . 6 5 4 2 . 5 C G L 7 6 2 8 5 2 0 9 4 3 f 4 . 8 6 I B - 3 3 7 n 2 7 5 4 3 * 4 2 . 5 O G L 8 0 3 2 8 2 4 8 5 . 7 7 II 4 2 . 5 C G L 7 5 2 8 5 2 1 0 4 3 f 4 . 8 8 I B - 3 3 4 II 2 7 5 4 2 . 5 O G L 7 6 3 2 6 2 5 0 4 3 f 5 . 8 1 II a T e m p e r a t u r e w h e n f u l l p r e s s u r e w a s a t t a i n e d . b F i n a l t e m p e r a t u r e o f o u t e r g l u e l i n e w a s t h a t a t t a i n e d w h e n C G L r e a c h e d 2 4 0 ° F . C F a c t o r X w a s c a l c u l a t e d b y d i v i d i n g t h e c h a n g e i n C G L T b y t i m e o f c h a n g e . ^ C G L i s c e n t r a l g l u e l i n e . e O G L i s o u t e r g l u e l i n e . ^ T w o 2 0 m i n u t e p r e s s i n g p l u s a 3 m i n u t e i n t e r v a l w i t h o u t p r e s s u r e . 104 T A B L E 9 T e s t i n g b r o a d l e a f m a p l e L V L f o r a d e q u a t e g l u e s p r e a d A n a l y s i s o f V a r i a n c e T a b l e V a r i a b l e S o u r c e DF S S MS C o m - S t a t i s t i c a l l y r a n k e d F m e n t m e a n s 3 . , . , S p r e a d 2 2 1 1 5 9 0 0 0 . 0 0 1 0 5 8 0 0 0 0 . 0 0 2 4 . 2 2 * * M a x . l o a d A g i n g 0 1 4 9 7 5 5 0 0 0 . 0 0 4 9 7 5 5 0 0 0 . 0 0 1 1 3 . 8 8 * * U b ; S p x A g 2 8 1 4 2 4 0 . 0 0 4 0 7 1 2 0 . 0 0 0 . 9 3 NS E r r o r 5 3 2 3 1 5 5 0 0 0 . 0 0 . 4 3 6 8 9 0 . 0 0 T o t a l 5 8 9 4 8 8 4 0 0 0 . 0 0 1 4 2 9 . 2 1 6 3 Q r Q 2 8 0 2 . 6 2 8 4 5 . 8 1 0 0 8 . 9 S p r e a d 2 1 4 6 2 1 0 0 . 0 0 7 3 1 0 3 0 . 0 0 2 3 . 9 0 * * D r y s h e a r A g i n g 1 3 4 6 8 5 0 0 . 0 0 3 4 6 8 5 0 0 . 0 0 1 1 3 . 4 0 * * s t r e n g t h S p x A g 2 8 3 1 6 8 . 0 0 4 1 5 8 4 . 0 0 1 . 3 6 N S I p s i J E r r o r 5 3 1 6 2 1 1 0 0 . 0 0 3 0 5 8 8 . 0 0 T o t a l . 5 8 6 6 3 4 9 0 0 . 0 0 3 5 3 . 6 3 9 7 . 8 7 1 0 . 4 7 2 1 . 9 2 3 6 . 9 S p r e a d 2 A g i n g 1 W o o d S p x A g 2 f a i l u r e {%) E r r o r 5 3 T o t a l 5 8 2 6 2 3 8 . 0 0 1 0 5 3 6 . 0 0 - 6 4 4 . 4 1 1 1 9 0 1 . 0 0 4 8 0 3 1 . 0 0 1 3 1 1 9 . 0 0 5 8 . 4 2 * * 1 0 5 3 6 . 0 0 4 6 . 9 2 * * - 3 2 2 . 2 0 - 1 . 4 3 NS 2 2 4 . 5 5 2 7 . 0 3 8 . 0 7 6 . 6 5 9 . 8 3 3 . 1 W o o d f a i l u r e S p r e a d 3 A g i n g 1 S p x A g 3 E r r o r 3 2 T o t a l 3 9 3 2 7 7 3 . 0 0 4 2 0 2 . 5 0 3 2 2 . 5 0 6 1 4 0 . 0 0 4 3 4 3 8 . 0 0 1 0 9 2 4 . 0 0 5 6 . 9 3 * * 2 ^ Q _ ^ 0 8 ^ 5 _ ^ l 4 2 0 2 . 5 0 2 1 . 9 0 * * 6 9 . 0 4 8 . 5 — 1 0 7 . 5 0 0 . 5 6 NS 1 9 1 . 8 7 a M e a n s u n d e r s c o r e d w i t h a c o m m o n l i n e a r e n o t s i g n i f i c a n t l y d i f f e r e n t a t 0 . 0 5 l e v e l . N u m b e r s i n p a r e n t h e s e s r e f e r t o e i t h e r g l u e s p r e a d l e v e l o r a g i n g . ' b S p r e a d s 1 , 2 , 3 , a n d 4 a r e 2 7 . 5 - , 3 0 - , 3 7 . 5 a n d 4 2 . 5 l b / M S G L r e s p e c t i v e l y . c A g i n g 1 a n d 2 a r e d r y t e s t a n d 2 4 - h o u r c o l d - s o a k , r e s p e c t i v e l y . + R e f e r s t o a n a l y s e s c a r r i e d o u t w i t h s a m p l e s o f 5 s p e c i e s f o r e a c h g l u e -s p r e a d l e v e l . N S S i g n i f i c a n t a t 0 . 0 1 l e v e l . N o t s i g n i f i c a n t . TABLE. 10 Mean and v a r i a b i l i t y of three strength p r o p e r t i e s of broadleaf maple LVL t e s t e d f o r adequate gluespread Spread (lb/MSGL) Aging V a r i a b l e Sample s i z e Mean Standard d e v i a t i o n C o e f f i c i e n t of v a r i a t i o n {%)'-27.5 Dry t e s t Max. load ( l b ) Shear s t r . ( o s i ) Wood f a i l u r e ' { % ) 10 10 10 2235.8 564.5 40.0 511.34 120.16 20.28 22.9 21.3 52.2 27.5 24-hour c o l d soak Max. load ( l b ) Shear s t r . ( p s i ) Wood f a i l u r e (%) 10 . 10 10 622.5 142.8 14.0 380.46 79.75 9.37 61.1 55.8 66.9 30 Dry t e s t Max. load ( l b ) Shear s t r . ( p s i ) Wood f a i l u r e (%) 10 10 10 2370.5 577.3 49.0 1096.83 255.07 11.97 46.3 44.2 24.4 30 24-hour c o l d soak Max. load ( l b ) Shear s t r . ( p s i ) Wood f a i l u r e {%) 10 10 10 905.2 . 208.3 27.0 447.61 . 95.18 18.44 49.2 45.7 68.3 37.5 Dry t e s t Max. load ( l b ) Shear s t r . ( p s i ) Wood f a i l u r e {%) 10 10 10 3931.0 1013.9 91.0 833.26 292.29 7.62 21.2 28.8 8.4 37.5 24-hour c o l d soak Max. load ( l b ) Shear s t r . ( p s i ) Wood f a i l u r e (%) 10 10 10 1548.9 373.2 61 278.38 85.15 17.81 18.0 22.8 29.2 TABLE 11 Mean and v a r i a b i l i t y of three strength p r o p e r t i e s of Broadleaf maple LVL t e s t e d f o r adequate gluespreads Spread Aging V a r i a b l e Sample s i z e Mean Standard d e v i a t i o n C o e f f i c i e n t of v a r i a t i o n * 27.5 Dry t e s t Max.load(lb) Dry shear s t r Wood f a i l u r e ; (? (%) s i ) 5 5 5 1951.6 469.5 38.0 476.00 169.89 23.61 24.4 36.2 62.1 27.5 24-hour c o l d soak Max.load ( l b ) Dry shear s t r Wood f a i l u r e {%) s i ) 5 5 5 501.0 115.1 12.0 222.02 44.34 9.75 44.3 33.5 • 81.2 30 Dry t e s t Max. load ( l b Dry shear s t r Wood f a i l u r e s i ) 5 5 5 2752.0 678.3 47.0 1344.70 295.32 12.04 48.9 43.5 25.6 30 24-hour co l d soak Max. load ( l b Dry shear s t r Wood f a i l u r e s i ) 5 5 5 948.8 216.0 25.0 448.60 94.25 19.04 47.3 43.6 76.2 37.5 Dry t e s t Max.. load ( l b Dry shear s t r Wood f a i l u r e s i ) 5 5 5 4467.0 1209.7 95.0 603.20 265.39 6.12 13.5 21.9 6.4 37.5 24-hour c o l d soak Max. load ( l b Dry shear s t r Wood f a i l u r e s i ) 5 5 1539.4 368.1 72.0 235.25 65.70 15.25 15.3 17.8 21.2 42.5 Max. load ( l b Dr y - t e s t Dry shear s t r Wood f a i l u r e s i ) 5 5 5 6223.0 1490.8 96.0 1362.24 317.63 6.52 21.9 21.3 6.8 42.5 24-hour Max. load ( l b co l d soak Dry shear s t r Wood f a i l u r e s i ) 5 5 5 2114.0 477.1 85.0 696.65 157.86 7.91 33.0 33.1 9.3 Subsamples of 5 were select e d randomly from samples i n spreads l t o 3 and were t e s t e d w i t h the samples of 5 obtained from spread panel. TABLE 12 T e s t i n g Broadleaf maple LVL f o r e f f e c t of p l a t e n temperature A n a l y s i s of v a r i a n c e t a b l e V a r i a b l e Source DF SS MS F Com-ment S t a t i s t i c a l l y ranked means 3 (1) (2) P l a t e n tempk Max. load A g i n g c ( l b ) P l a t . T x Ag E r r o r T o t a l 1 1 1 16 19 281.25 695830C0.*00 716310.00 14030000.00 84330000.00 .. 281.25 69583000.00 716310.00 876900.00 0.00 79.35 0.82 NS ** NS 4168.5 4176.0 6037.5 2307.0 P l a t e n temp 1 1111.50 Dry shear Aging 1 4055000.00 st r e n g t h P l a t . T x Ag 1 63924.00 ( p s i ) E r r o r 16 595540.00 T o t a l 19 4715500.00 1111.50 0.03 4055000.00 108.94 63924.00 1.72 37221.00 NS *-* NS 984.0 1426.8 969JL 526.3 P l a t e n temp 1 7.20 7.20 . 0.07 NS 90.5 89.3 Wood Aging 1 720.00 720.00 7.32 95.9 83.9 f a i l u r e P l a t . T x Ag 1 5.00 5.00 0.05 NS {%) E r r o r T o t a l 16 19 1573.60 2305.80 98.35 Means underscored w i t h a common l i n e are not s i g n i f i c a n t l y d i f f e r e n t at 0.05 ' l e v e l . Numbers i n parentheses r e f e r t o pla t e n temperature and aging l e v e l s . b P l a t e n temperature 1 i s 300°F and 2 i s 400°F. c Agings 1 and 2 are dry t e s t and 24-hour c o l d soak, r e s p e c t i v e l y . TABLE .13 Mean and v a r i a b i l i t y of three strength p r o p e r t i e s of broadleaf maple LVL te s t e d f o r e f f e c t of plat e n temperature P l a t e n temp. (°F) Aging V a r i a b l e Sample s i z e Mean Standard d e v i a t i o n C o e f f i c i e n t of v a r i a t i o n {%) 300 Dry -test Max. load ( l b ) Shear s t r . ( p s i ) Wood f a i l u r e {%) 5 5 5 6223.0 1490.8 96.0 1362.24 317.63 6.52 21.9 21.3 6.8 300 24-hour c o l d soak Max.load ( l b ) Shear s t r . ( p s i ) Wood f a i l u r e (%) 5 5 5 2114.0 477.1 85.0 696.65 157.86 7.91 33.0 33.1 9.3 400 Dry t e s t Max. load ( l b ) Shear s t r . ( p s i ) Wood f a i l u r e {%) 5 5 5 5852.0 1362.8 96.0 918.35 74.58 1.30 15.7 5.5 1.4 400 24-hour c o l d soak Max. load ( l b ) Shear s t r . ( p s i ) Wood f a i l u r e {%) 5 5 5 2500.0 575.3 83.0 568.54 132.39 16.93 22.7 23.0 20.4 I—1 o CO TABLE 14 Testing broadleaf maple LVL f o r adequate curing temperature A n a l y s i s of variance t a b l e V a r i a b l e Source DF SS MS F Com-ment S t a t i s t i c a l l y ranked means 3 Dry shear strength ( p s i ) CGL TempD A g i n g 0 CGL T x Ag Er r o r T o t a l 2 210070.00 2 10080000.00 4 78648.00 36 702040.00 44 11070000.00 105040.00 5039800.00 19662.00 19501.00 5.39 258 .-44 1.01 (1) 853.4 (2) 934.1 ** 1605.2 NS (3) 1020.7 615.9 587.2 CGL Temp 2 1456.10 ' 728.07 12.43 *•* 85.9 98.6 97.1 Wood Aging 2 474.53 237.27 4.05 *• 98.0 93.5 90,1 f a i l u r e CGL T x Ag 4 390.13 97.53 1.67 NS (%) E r r o r 36 2108.40 58.57 T o t a l 44 4429.20 CGL Temp 2 3403800.00 1701900.00 5.03 -* 3579.3 3833,6 4246.7 Max. load Aging 2 152920000.00 76471000.00 226.05 6493.0 2630,6 2536,1 (lb ) CGL T x Ag 4 1284100.00 321030.00 0.95 NS Er r o r 36 12177 000.00 338250.34 T o t a l 44 169290000.00 Means underscored w i t h a common l i n e are not s i g n i f i c a n t l y d i f f e r e n t at 0.05 l e v e l . Numbers i n parentheses r e f e r t o g l u e l i n e temperature and aging l e v e l s , respec-t i v e l y . C e n t r a l g l u e l i n e temperature 1 i s 233°F; c e n t r a l g l u e l i n e temperature 2 i s 240°F; c e n t r a l g l u e l i n e temperature 3 i s 300°F. cAgings 1, 2 and 3 are dry t e s t , 24-hour c o l d soak and c y c l i c (vac/press)soak, r e s p e c t i v e l y . TABLE 15 Mean and v a r i a b i l i t y of three strength p r o p e r t i e s of broadleaf maple LVL te s t e d f o r adequate cur i n g temperature CGL Temp' Aging' V a r i a b l e Sample s i z e Mean Standard d e v i a t i o n C o e f f i c i e n t of v a r i a t i o n 233 Dry-test Max. load ( l b) Dry shear ( psi) Wood f a i l u r e (%) 5 5 5 5852.0 1439.2 95.8 918.36 217.03 1.30 15.7 15.1 1.4 233 24-hour c o l d soak Max. load ( l b) Dry shear ( p s i ) Wood f a i l u r e (%) 5 5 5 2500.0 575.3 82.8 568.54 132.39 16.93 22.7 23.0 20.4 233 C y c l i c (vac/ press) soak Max. load (lb) Dry shear ( p s i ) Wood f a i l u r e (%) 5 5 5 2386.0 545.7 79.0 357.90 79.12 12.94 15.0 14.5 16.4 240 Dry-test Max. load ( l b ) Dry shear ( p s i ) Wood f a i l u r e {%) 5 5 5 6567.0 1639.1 99.4 805.56 197.75 0.90 12.3 12.1 0.9 240 24-hour c o l d soak Max. load ( l b ) Dry shear ( p s i ) Wood f a i l u r e (%) 5 5 5 2492.8 594.1 99.2 319.40 77.16 0.84 12.8 13.0 0.8 240 C y c l i c (vac/ press) soak Max. load ( l b) Dry shear ( p s i ) Wood f a i l u r e (%) 5 5 5 2441.0 569.2 97.2 374.42 92.90 4.38 15.3 16.3 4.5 300 Dry-test Max. load ( l b) Dry shear ( psi) Wood f a i l u r e (%) 5 5 5 7060.0 1737.3 98.8 786.13 194.65 1.79 11.1 11.2 1.8 300 24-hour c o l d soak Max. load ( l b) Dry shear ( psi) Wood f a i l u r e (%) 5 5 5' 2899.0 678.3. 98.6 391.88 89.57 2.19 13.5 13.2 2.2 300 C y c l i c (vac/ Dress) soak Max. load (lb) Dry shear ( p s i ) Wood f a i l u r e (%) 5 5 5 2781.2 646.6 9 4 , 0 294.70 70.90 6,52 10.6 11.0 6.9 I l l TABLE 10 E f f e c t of pressure on c e r t a i n c h a r a c t e r i s t i c s of broadleaf maple LVL — — — ~~~ ~~ Sample Pressure Aging Variable Mean SD CV size 200 Dry t e s t Shear strength (psi) 1639.1 197.75 12.1 5 II II II . Wood f a i l u r e {%) 99.4 0.90 0.9 5 It II II LVL thickness (in) 1.548 0.11 0.7 5 II 24-hour Shear strength ( p s i) 594.1 77.5 13.0 5 cold soak Wood f a i l u r e {%) 0.84 0.8 II II II 99.2 5 11 it it LVL thickness (in) 1.637 0.006 0.4 5 It C y c l i c (vac/ Shear strength (psi) 569.2 92.90 16.3 5 It press) soak ti it Wood f a i l u r e (%) 97.2 4.38 4.5 5 II II it LVL thickness (in) 1.660 0.009 0.5 5 250 Dry t e s t Shear strength (psi) 1965.3 357.9 18.2 5 II n II Wood f a i l u r e {%) 100 0 0 5 II it II LVL thickness (in) 1.351 0.007 0.5 5 II 24-hour Shear strength ( p s i) 743.8 142.8 19.2 5 cold soak Wood f a i l u r e [%) II it it 100 .0 0 5 II ti tt LVL thickness (in) 1.568 0.009 0.6 5 It C y c l i c (Vac/ Shear strength (psi) 713.4 75.3 10.6 10 II press) soak r it ii Wood f a i l u r e (%) 100 0 0 10 II it ii LVL thickness (in) 1.622 0.012 0.7 10 275 Dry t e s t Shear strength (psi) 2000.3 198.2 9.9 5 it n n Wood f a i l u r e {%) 100 0 0 5 ti ti ii LVL thickness (in) 1.296 0.010 0.8 5 it 24-hour Shear strength (psi) 710.4 78.4 11.0 5 cold soak Wood f a i l u r e {%) 100 0 II it n 0 5 II ii tt LVL thickness (in) 1.577 0.010 0.6 5 II C y c l i c (vac/ Shear strength (psi) 632.4 66.4 10.5 10 II press) soak II II Wood f a i l u r e {%) 100 0 0 10 n it it LVL thickness (in) 1.612 0.008 0.5 10 TABLE 17 Testing black cottonwood fox adequate gluespread of phenolic r e s i n glue IB-337 3 Analys i s of variance t a b l e V a r i a b l e Source DF SS MF F Com-ment S t a t i s t i c a l l y ranked means" Dry shear s t r . ( p s i ) Spread 0 Agingd Sp x A g e E r r o r T o t a l 2 1 2 84 89 3101400.. 00 8010800.00 42696.00 1381900.00 12537000.00 1550700.00 8010800.00 21348.00 16452.00 94.26 486.93 1.30 -** ** NS (1) (2) (3) 323.4 602.1 733.9 864.8 268.1 Wood f a i l u r e {%) Spread Aging Sp x Ag Er r o r T o t a l 2 1 2 84 89 64099.00 6117.40 990.96 19807.00 91014.00 ; 32050.00 6117.40 495.48 235.80 135.92 25.94 2.10 NS 29.6 79.7 91.1 75.0 58.6 A d j . shear strength ( p s i ) Spread E r r o r T o t a l 2 42 44 1762300.00 1018400.00 2780700.00 881160.00 24248.00 36.34 555.7 864.1 1033.7 aIB-337 i s a phenol-formaldehyde r e s i n manufactured by Reichhold Chemicals (Canada) L i m i t e d , Vancouver, B.C. Means underscored w i t h a common liner.are not s i g n i f i c a n t l y d i f f e r e n t . Numbers i n parentheses r e f e r to spread or aging. Same numbers r e f e r to both spread and aging. cSpread 1 i s 30 lb/MSGL; spread 2 i s 37.5 lb/MSGL; spread 3 i s 42.5'lb/MSGL. ^Aging 1 i s dry t e s t under l a b o r a t o r y c o n d i t i o n ; 2 i s c y c l i c (vacuum/pressure) soak. i n t e r a c t i o n term. ^ S i g n i f i c a n t at 0.01 or h i g h l y s i g n i f i c a n t . NS Not s i g n i f i c a n t . TABLE 18 Mean and v a r i a b i l i t y of some strength p r o p e r t i e s of black cottonwood LVL at d i f f e r e n t l e v e l s of gluespread^ Spread (lb/MSGL) Aging V a r i a b l e Sample s i z e Mean Standard d e v i a t i o n C o e f f i c i e n t of v a r i a t i o n (#) 30 Dry t e s t Dry shear s t r . ( p s i ) A d j . shear s t r . ( p s i ) Wood f a i l u r e {%) 15 15 15 593.7 555.7 41.7 160.99 153.33 25.34 27.1 27.6 60.7 30 C y c l i c (vac/press) soak Dry shear s t r . ( p s i ) Wood f a i l u r e {%) 15 15 53.1 17.5 39.89 15.53 75.2 88.6 37.5 Dry t e s t Dry shear s t r . ( p s i ) A d j . shear s t r . ( p s i ) Wood f a i l u r e {%) 15 15 15 903.4 864.1 88.3 169.08 167.41 14.54 18.7 19.4 16.5 37.5 C y c l i c (vac/press) soak Dry shear s t r . ( p s i ) Wood f a i l u r e {%) 15 15 300.7 71.1 101.81 12.06 33.9 17.0 42.5 Dry t e s t Dry shear s t r . ( p s i ) A d j . shear s t r . ( p s i ) Wood f a i l u r e {%) 15 15 15 1097.3 1033.7 95.1 160.56 145.63 5.62 14.6 14.1 5.9 42.5 C y c l i c (vac/press) soak Dry shear s t r . ( p s i ) Wood f a i l u r e {%) 15 15 450.5 87.1 80.44 11.95 17.9 13.7 Laminated Veneer Lumber ^Gluespread of phenol-formaldehyde r e s i n glue IB-337 manufactured by Reichhold Chemicals.(Canada) L i m i t e d , Vancouver, B.C. TABLE 19 Testing black cottonwood LVL f o r e f f e c t of p r e s s i n g 3 at 69 and 100 p s i r e s p e c t i v e l y A n a l y s i s of variance t a b l e Variable-' Source DF SS MF F Com-ment S t a t i s t i c a l l y ranked means Dry shear s t r . ( p s i ) P r e s s u r e 0 A g i n g a Pr x A g e E r r o r T o t a l 1 1 1 56 59 225460.00 6421000.00 83627.00 649690.00 7297000.00 225460.00 6421000.00 83627.00 11602.00 19.43 553.46 0.07 -3BC-#-x-NS U ) 773.9 1162.3 (2) 896.5 508.0 Wood f a i l -ure (%) Pressure Aging Pr x Ag E r r o r T o t a l 1 1 1 56 59 777.60 365.07 141.07 3083.60 4367.30 777.60 365.07 141.07 55.06 14.12 6.63 2.56 -X--X-•* NS 91.1 97.1 98.3 92.2 A d j . shear streng t h ( p s i ) Pressure E r r o r T o t a l 1 28 29 111870.00 430770.00 541940.00 111870.00 15360.00 7.28 * 1033.7 1155.9 a Glue spread was 42.5 lb/MSGL and c e n t r a l g l u e l i n e s were heated to 240°F w i t h 350°F pl a t e n s . ' ^Means underscored w i t h a common l i n e are not s i g n i f i c a n t at 0.05 l e v e l . c P r e s s u r e 1 i s 69 p s i and pressure 2 i s 100 p s i . ^Aging .1 i s dry t e s t at l a b o r a t o r y c o n d i t i o n ; aging 2 i s c y c l i c (vacuum/pressure soak. i n t e r a c t i o n term. TABLE 20 Mean and v a r i a b i l i t y of some strength p r o p e r t i e s of black cottonwood LVL at two l e v e l s of plat e n pressure' 3 P l a t e n pressure ( p s i ) Aging V a r i a b l e - Sample s i z e Mean Standard d e v i a t i o n C o e f f i c i e n t of v a r i a t i o n {%) 69 Dry t e s t Dry shear s t r . A d j . shear s t r . Wood f a i l u r e {% (ps i ) ( p s i ) 15 15 15 1097.3 1033.7 95.1 160.56 145.63 5.63 14.6 14.1 5.9 69 C y c l i c (vac/press soak ,Dry shear s t r . 'Wood f a i l u r e {% (ps i ) ) 15 15 450.5 87.1 80.44 11.95 17.9 13.7 100 Dry t e s t Dry shear s t r . A d j . shear s t r . Wood f a i l u r e {% (p s i ) ^ ( p s i ) 15 15 15 1227.3 1155.9 99.2 100.06 97.53 0.86 8.2 8.4 0.9 100 C y c l i c (vac/press soak Dry shear s t r . )Wood f a i l u r e {% ( p s i ) ) 15 15 565.6 97.3 64.38 6.72 11.4 6.9 a Laminated Veneer Lumber P l a t e n s i z e i s 16 inches by 16 inches; LVL boards were 8 inches by 12 inch e s . TABLE 21 Testing sugar maple LVL f o r adequate gluespread of phenolic r e s i n glue IB-337 3 A n a l y s i s of variance t a b l e V a r i a b l e Source DF SS MF F Com-ment S t a t i s t i c a l l y ranked means" (1) (2) (3) Dry shear s t r . ( p s i ) Spread 0 A g i n g e Sp x Ag Er r o r T o t a l 2 1 2 84 89 28811000.00 45624000.00 1162000.00 7907400.00 83504000.00 14405000.00 45624000.00 581000.00 94136.00 153.03 484.66 6.17 N0 d NU Wood f a i l -ure {%) Spread Aging Sp x Ag Er r o r T o t a l 2 1 2 84 89 50683.00 9589.30 232.16 15663.00 76167.00 25342.00 9589.30 116.08 186.46 135.91 51.43 0.62 *-* NS 34.3 74.0 90.9 A d j . shear s t r . ( p s i ) Spread E r r o r T o t a l 2 42 44 16965000.00 5938500.00 22904000.00 8482600.00 141390.00 59.99 ** 1191.4 1856.8 2692.2 aIB-337 i s a phenol-formaldehyde r e s i n manufactured by Reichhold Chemicals (Canada) L i m i t e d , Vancouver, B.C. "Means underscored w i t h a common l i n e are not s i g n i f i c a n t l y d i f f e r e n t at 0.05 l e v e l . Numbers i n parentheses r e f e r t o spread and aging. cSpread 1 i s 30 lb/MSGL; spread 2 i s 37.5 lb/MSGL; spread 3 i s 42.5 lb/MSGL. a F - v a l u e not u s e f u l because i n t e r a c t i o n i s s i g n i f i c a n t . o e A g i n g 1 i s dry t e s t under l a b o r a t o r y c o n d i t i o n ; aging 2 i s c y c l i c (vac/press)soak. ^ S i g n i f i c a n t at 0.01, i . e . h i g h l y s i g n i f i c a n t . TABLE 22 Mean and v a r i a b i l i t y of some strength p r o p e r t i e s of sugar maple LVL at d i f f e r e n t l e v e l s of gluespread' 3 Spread (lb/MSGL Aging V a r i a b l e Sample s i z e Mean Standard devia-t i o n C o e f f i c i e n t of v a r i a t i o n {%) 30 Dry t e s t Dry shear s t r . ( p s i ) A d j . shear s t r . ( psi) Wood f a i l u r e {%) 15 15 15 1307.2 1191.4 46.5 470.78 430.54 22.56 36.0 36.7 48.5 30 C y c l i c (vac/ press) soak Dry shear s t r . ( p s i ) Wood f a i l u r e {%) 15 15 145.0 22.0 86.02 9.29 59.3 42.2 37.5 Dry t e s t Dry shear s t r . ( p s i ) A d j . shear s t r . ( p s i ) Wood f a i l u r e {%) 15 15 15 1999.5 1856.8 84.4 492.11 447.66 14.39 24.6 24.1 17.0 37.5 C y c l i c (vac/ press) soak Dry shear s t r . ( p s i ) Wood f a i l u r e {%) 15 15 606.1 63.7 195.35 13.56 32.2 21.3 42.5 Dry t e s t Dry shear s t r . ( p s i ) A d j . shear s t r . ( p s i ) Wood f a i l u r e {%) 15 15 15 2964.0 2962.2 99.2 200.94 179.82 1.47 6.8 6.7 1.5 42.5 C y c l i c (vac/ press) soak Dry shear s t r . ( psi) Wood f a i l u r e {%) 15 15 1247.7 82.5 122.77 11.43 9.8 13.8 a Laminated Veneer Lumber Glue used was phenol-formaldehyde r e s i n glue IB-337 manufactured by Reichhold Chemicals,(Canada) L i m i t e d , Vancouver, B.C. TABLE 23 Testing sugar maple LVL f o r e f f e c t of p r e s s i n g 3 at 250 and 275 p s i , r e s p e c t i v e l y A n a l y s i s of variance t a b l e SS MF Com- S t a t i s t i c a l l y V a r i a b l e Source DF F me nt ranked meansh P r e s s u r e 0 1 960890.00 960890.00 22.42 (1) (2) Dry shear Aginge 1 51317000.00 51317000.00 1197.24 NU s t r . ( p s i ) Pr x Ag* 1 266530.00 266530.00 6.22 •* E r r o r 56 2400300.00 42863.00 T o t a l 59 54945000.00 Wood f a i l -ure Pressure Aging Pr x Ag Erro r T o t a l 1 1 1 56 59 442.82 1653.80 570.42 2303.60 4970.60 442.82 1653.80 570.42 41.14 10.76 40.20 13.87 NU NU Ad j . shear s t r . ( p s i ) Pressure E r r o r T o t a l 1 747970.00 28 1638700.00 29 2386600.00 747970.00 58524.00 12.78 2692.2 3008.0 a + o Gluespread 3 was ap p l i e d t o a l l boards and c e n t r a l g l u e l i n e was heated t o 240.. I F before removing pressure. kfvieans not underscored w i t h a common l i n e are s i g n i f i c a n t l y d i f f e r e n t at 0.05 l e v e l . When i n t e r a c t i o n i s s i g n i f i c a n t , Duncan's M u l t i p l e Range Test i s not c a r r i e d out. c P r e s s u r e s 1 and 2 were 250 and 275 p s i , r e s p e c t i v e l y . "%-value not u s e f u l because i n t e r a c t i o n term i s s i g n i f i c a n t l e v e l . e A g i n g 1 and 2 were dry t e s t e d under l a b o r a t o r y c o n d i t i o n s , and c y c l i c (vacuum/ pressed) soak, r e s p e c t i v e l y . •^Interaction term. CO •x-S i g n i f i c a n t at 0.05 l e v e l . ^ S i g n i f i c a n t at 0.01 l e v e l , i . e . h i g h l y s i g n i f i c a n t . TABLE 24 Mean and v a r i a b i l i t y of some strength p r o p e r t i e s of sugar maple LVL a at two l e v e l s of p l a t e n ^ pressure P l a t e n pressure ( p s i ) Aging V a r i a b l e Sample s i z e Mean Standard devia-t i o n C o e f f i c i e n t of v a r i a t i o n 250 Dry shear s t r . ( p si) Dry t e s t A d j . shear s t r . ( p s i ) Wood f a i l u r e {%) 15 15 15 2964.0 2692.2 99.2 200.94 179.82 1.47 6.8 6.7 1.5 250 C y c l i c (vac/ Dry shear s t r . ( p s i ) press) soak Wood f a i l u r e {%) 15 15 1247.7 82.5 122.77 11.43 9.8 13.8 275 Dry shear s t r . ( p s i ) Dry t e s t A d j . shear s t r . ( p si) Wood f a i l u r e {%) 15 15 15 3350.4 3008.0 98.5 323.35 231.04 2.70 9.7 9.7 2.7 275 C y c l i c (vac/ Dry shear s t r . ( p si) press) soak Wood f a i l u r e {%) 15 15 1367.5 94.1 106.94 4.96 7.8 5.3 Laminated Veneer Lumber P l a t e n s i z e i s 16 inches by 16 inches TABU; 25 Hffect of pressing time and glue on somp strength and related properties of sugar maple I.VLa Analysis of variance table Phenolic resin Aging glue Variable Source DF SS MS F Com-ment S t a t i s t i c a l l y ranked means" IB-337 & IB-334 Dry tes t Dry shear str (psi) Press time 0 Gliied Pr.T x G l e Error Total 1 1 1 56 59 156470.00 3292900.00 6244200.00 3513200.00 13207000.00 156470.*00 3292900.00 6244200.00 62736.00 2.49 52.49 99.53 NU NU *-* (1) (2) • H n Wood f a i l u r e (%) Press time Glue Pr.T x Gl Error Total 1 1 1 56 59 228.15 120.42 126.15 1104.10 1578.80 228.15 120.42 126.15 19.72 11.57 6.11 6.40 NU NU * II it it LVL thick-ness (in) Press time Glue Pr.T x Gl Error To'tal 1 1 1 56 59 16667x10-10 7706~xl0-9 6x10-' 223x10-5 16667x10-10 77067x10-9 6x10-7 39821x10-9 0.04 1.94 0.02 NS NS NS II n II Moisture content (%) Press time Glue Pr.T x Gl Error Total 1 1 1 56 59 15647x10-3 58907x10-6 50460x10-6 45919xl0~ 4 20348xl0- 3 15647x10-3 58907xl0" 6 50460x10-6 81999x10"° 190.82 0.72 0.62 ## NS NS 3.53 2.51 3.05 2.99 IB-337 II H Adj. shear str .H psi) Press time Error Total 1 28 29 4313800.00 1399100.00 5712900.00 4313800.OC 49968.OC i 86.33 i ** 3008.0 2249.6 IB-334 Dry test Adj. shear s t r . ( p s i ) Press time Error Total 1 28 29 1237900.00 1407100.00 2645000.00 1237900.00 50253.00 24.63 ** IB-337 Cyclic & (vac/ IB-334 press) soak Dry shear s t r . ( p s i ) Press t i . T i e Glue Pr.T x Gl Error Total 1 1 1 56 59 3904.30 601.67 363790.00 900840.00 1269100.00 3904.30 601.67 363790.00 16086.00 0.24 0.04 22.61 NU NU *~* " Wood Press time 1 742.02 742.02 9.46 NU II Glue 1 93.75 93.75 1.20 NU f a i l u r e la/ \ Pr.T x Gl 1 3360.00 3360.00 42.83 ** \%) Error 56 4392.80 78.44 Total 59 8588.60 LVL Press tir.e 1 68267xl0- 9 68267x10-9 0.96 NU 11 " thickness Glue 1 86400x10-9 86400x10-9 1.22 NU (in) Pr T x Gl 1 38507xl0~ 8 38507x10-8 5.42 * Error 56 39812x10-7 71903x10-9 Total 59 45209xl0- 7 Press time 1 665.07 665.07 299.83 NU II Moisture Glue 1 181.45 181.45 81.80 NU " content Pr.T x Gl 1 20.28 20.28 9.14 ** {%) Error 56 124.22 2.22 Total 59 991.01 3Gluespread was 42.5 lb/'<tSGL and LVL boards were pressed at 275 p s i . ''Means underscored with a common l i n e are not s i g n i f i c a n t l y d i f f e r e n t at 0.05 l e v e l . Those not underscored at a l l d i f f e r s i g n i f i c a n t l y at 0.05 l e v e l . Numbers i n paren-theses refer to pressing time and glue type, c Pressing time 2 i s two 20-rcinute cycles with a three-minute i n t e r v a l . This pressing time was used to simulate the portion.of the continuous LVL that i s usually pressed twice. r-ho • , i I ? ^ 3 3 ? , i ? ? laminating phenol-formaldehyde r e s i n manufactured by the Reichhold tolerance 5. ' V a n C 0 u v e r ' 3- C- : I B " 3 3 4 i s a modification of IB-337 for dryout e Interaction term. Glueline shear strength adjusted to i t s 7% MC value ( p s i ) . This variable was not available for the c y c l i c (vacuum/presGure) soak. Hence simple analysis of variance test was used. F-value not useful because interaction term i s s i g n i f i c a n t , * * S i g n l f i c a n t at 0.01 l e v e l , i . e . highly s i g n i f i c a n t . • S i g n i f i c a n t at 0.05 l e v e l . 121 TABLE 26 i Mean and v a r i a b i l i t y of some strength and related properties of sugar maple LVL as affected by press time 3 and type of glue^ Press Phenolic time resin Aging (min) glue Variable Sample Mean size Coeff ic ient Standard °* var iat ion deviation {%) 20 IB-337 Dry test Dry shear s t r . (psi) lb 3350.70 323.00 g~~£~ Adj . shear s t r . (psi) 15 3008.00 291.04 9^7 Wood fa i lu re (%) 15 98.50 2.70 2.7 LVL thickness (in) 15 1.55 0.07 0.4 Moisture content (%) 15 3.59 0.14 4.0 20 40 20 Dry shear s t r . (psi) 15 Cyc l ic Wood fa i lu re {%) 15 (vac/press) LVL thickness (in) 15 _soa_lc Moisture content {%) 15 1367.50 94.10 1.66 95.68 106.94 4.96 0.01 1.41 Dry shear s t r . (psi) 15 Cyc l ic Wood fa i lu re {%) 15 (vac/press) LVL thickness (in) 15 s o a k Moisture content (%) 15 1227.90 86.20 1.65 101.17 IB-334 Dry test Dry shear s t r . (psi) 15 2236.90 Adj . shear s t r . (psi) 15 1999.60 Wood f a i l u r e {%) . 15 92.70 LVL thickness (in) 15 1.55 Moisture content {%) 15 3.47 167.28 11.69 0.04 2.19 303.87 268.12 8.31 0.01 0.30 7.8 5.3 0.6 1.5 Dry shear s t r . (psi) 15 2603.30 147.10 5.7 Adj . shear s t r . (psi) 15 2249.60 123.37 5.5 40 " Dry test Wood fa i lu re {%) 15 99.50 1.41 1.4 LVL thickness (in) 15 .1.55 0.05 0.5 Moisture content {%) 15 2.51 0.22 8.9 13.6 13.6 0.5 2.2 13.6 13.4 9.0 0.5 8.6 20 20 20 Dry s h e a r s t r , (psi) 15 Cyc l ic Wood fa i lu re {%) 15 (vac/press) LVL thickness (in) 15 soak Moisture content {%) 15 Dry shear s t r . (psi) 15 Adj . shear s t r . (ps i ) 15 Dry test Wood fa i lu re {%) 15 LVL thickness (in) 15 Moisture content (%) 15 1205.40 76.70 1.65 91.04 2730.00 2405.90 99.50 1.55 2.51 132.25 12.05 0.01 0.67 180.63 169.16 0.74 0.00 0.41 Dry shear s t r . (psi) 15 1377.30 86.22 Cycl ic Wood fa i lu re {%) 15 98.70 2.72 (vac/press)LVL thickness (in) 15 1.66 0.01 ?oak Moisture content {%) 15 98.86 1.30 11.0 15.7 0.5 0.7 6.5 7.0 0.7 0.0 16.4 6.3 2.8 0.6 1.3 Pressing time of 40 minutes consists of two 20-minute press cycles with an interva l of three minutes in between. This i s to simulate the portion of continuous board pressed twice, with the three minute in terva l between press cyc les . bPhenol-formaldehyde resin IB-337 and IB-334 were used, the la t te r beinq a modification of the former for dryout resistance. TABLE 27 Testing sugar maple LVL f o r adequate gluespread w i t h p h e n o l - r e s o r c i n o l glue a A n a l y s i s of variance table Com- S t a t i s t i c a l l y ment ranked means 0 V a r i a b l e1 Source DF SS MS TIT T2T TsT Dry shear Spread 1 512450.00 512450.00 14.25 NU strength Aging 1 23982000.00 23982000.00 666.97 NU (p s i ) Sp x Ag 1 939750.00 939750.00 26.14 Er r o r 56 2013600.00 35957.00 To t a l 59 27448000.00 Spread 1 138.02 138.02 6.48 96.5 99.5 Wood Aging 1 28.02 28.02 1.31 NS 98.7 97.3 f a i l u r e Sp x Ag 1 25.35 25.35 1.19 NS {%) E r r o r 56 1193.60 21.31 To t a l 59 1385.00 Adjusted Spread 1 1558200.00 1558200.00 27.18 •** 2692.1 2236.3 shear s t r . Er r o r 28 1605000.00 57323.00 ( p s i ) T o t a l 29 3163200.00 ^Gluespreads 2 and 3,. are 37.5 and 42.5 lb/MSGL, r e s p e c t i v e l y ; agings 1 and 2 were dry t e s t and c y c l i c (vacuum/pressure) soak. ^ V a r i a b l e 2 i s g l u e l i n e shear strength adjusted t o i t s 1% MC value. Q Means underscored w i t h a common l i n e are not s i g n i f i c a n t l y d i f f e r e n t at 0.05 l e v e l . Those not underscored at a l l are s i g n i f i c a n t l y d i f f e r e n t at 0.05 l e v e l . Numbers i n parentheses r e f e r to gluespreads or aging. S i g n i f i c a n t at 0.01 l e v e l , i . e . h i g h l y s i g n i f i c a n t ; S i g n i f i c a n t at 0.05 l e v e l . t—• ro ro NS Not s i g n i f i c a n t . N U F - v a l u e not u s e f u l because i n t e r a c t i o n term i s s i g n i f i c a n t . TABLE 28 Mean and v a r i a b i l i t y of some s t r e n g t h p r o p e r t i e s of phenol- r e s o r c i n o l -bonded sugar maple LVL at two l e v e l s of gluespread Spread (lb/MSGL) a Aging V a r i a b l e Sample s i z e Mean Standard d e v i a -t i o n C o e f f i c i e n t of v a r i a t i o n (%) 37.5 Dry t e s t Dry shear s t r . ( p s i ) A d j . shear s t r . ( p s i ) Wood f a i l u r e {%) 15 15 15 2724.3 2692.1 97.8 309.64 'v 320.92 4.00 11.4 11.9 4.1 37.5 C y c l i c (vac/press) soak Dry shear s t r . ( p s i ) Wood f a i l u r e {%) 15 15 1209.5 95.1 169.19 8.17 13.0 8.6 ' 42.5 Dry t e s t Dry shear s t r . ( p s i ) A d j . shear s t r . ( p s i ) Wood f a i l u r e {%) 15 15 15 2289.1 2236.3 99.5 91.37 107.94 1.13 4.0 4.8 1.1 42.5 C y c l i c (vac/press) soak Dry shear s t r . ( p s i ) Wood f a i l u r e {%) 15 15 1275.0 99.5 104.73 1.13 8.2 1 - 1 a Gluespreads lower than 37.5 were d i f f i c u l t t o spread w i t h brush, hence were not inc l u d e d i n t h i s t e s t . TABLE 29 Testing black cottonwood LVL fox bond q u a l i t y w i t h phenol- r e s o r e i n o l glue a A n a l y s i s of variance t a b l e V a r i a b l e Source DF SS MS F Com-ment S t a t i s t i c a l l y ranked means*3 Dry shear s t r . ( p s i ) Aging Er r o r T o t a l 1 28 29 1225700.00 153310.00 1379000.00 1225700.00 5473.30 223.87 (1) 985.3 ? , 581.1 Wood f a i l -ure {%) Aging Er r o r T o t a l 1 28 29 0.30 17.07 17.37 0.30 0.61 0.49 NS 99,9 99.7 a -The only spread used was 42.5 lb/MSGL. C e n t r a l g l u e l i n e was heated to .216--2°F using p l a t e n temperature and pressure of 350°F and p s i , r e s p e c t i v e l y . Means underscored w i t h a common l i n e are not s i g n i f i c a n t l y d i f f e r e n t at 0.05 l e v e l whereas those not underscored d i f f e r . Numbers i n parentheses r e f e r to the aging. S i g n i f i c a n t at 0.01 l e v e l . Not s i g n i f i c a n t . TABLE 30 Mean and v a r i a b i l i t y of three strength p r o p e r t i e s of .phenol resorcinol-bonded black cottonwood LVL Aging V a r i a b l e Sample si z e Mean Standard d e v i a t i o n C o e f f i c i e n t of v a r i a t i o n (%) Dry t e s t Dry A d j . Wood shear s t r . ( p s i ) shear s t r . ( p s i ) f a i l u r e (%) 15 15 15 985.3 966.1 99.9 66.12 73.51 0.35 6.7 7.6 0.4 C y c l i c (vac/press) soak Dry Wood shear s t r . ( p s i ) f a i l u r e (%) 15 15 581.1 99.7 81.11 1.05 14.0 1.1 T A B U : 31 M e a n a n d v a r i a b i l i t y o f s o m e s t r e n g t h a n d r e l a t e d p r o p e r t i e s o f t h e t h r e e s e c t i o n s o f c o n t i n u o u s L V L 126 W o o d s p e c i e s A g i n g P h e n o l i c g l u e S e c t i o n 3 V a r i a b l e S a m p l e S t a n d a r d s i z e M e a n d e v i a t i o n C o e f f i c i e n t o f v a r i a -t i o n {%) S u g a r D r y t e s t m a p l e I B - 3 3 7 D r y s h e a r s t r . J p s i A d j . s h e a r s t r . W o o d f a i l u r e ( 9 2 1 3 8 . 6 0 2 0 5 . 0 5 9 . 6 9 2 0 4 0 . 8 0 1 9 4 . 0 5 9 . 5 9 9 5 . 0 0 3 . 2 8 3 . 5 L V L t h i c k n e s s ( i n ) 9 1 . 5 8 0 . 0 0 0 . 0 D r y s h e a r s t r . ( p s i ) 1 2 2 3 2 6 . 4 0 2 4 3 . 3 3 1 0 . 5 A d j . s h e a r s t r . ( p s i ) 1 2 2 2 0 4 . 1 0 2 3 9 . 6 3 1 0 . 9 " 2 W o o d f a i l u r e {%) 1 2 9 3 . 8 0 7 . 3 5 7 . 8 L V L t h i c k n e s s ( i n ) 1 2 1 . 5 8 0 . 0 0 0 . 8 M o i s t u r e c o n t e n t(jo) 1 2 5 . 2 4 0 . 2 9 5 . 5 II II II D r y s h e a r s t r . ( p s i ) 1 4 1 0 6 5 . 2 0 9 3 1 . 3 0 8 7 . 5 A d j . s h e a r s t r . ( p s i ) 1 4 1 0 2 3 . 1 0 8 9 5 . 3 6 8 7 . 5 W o o d f a i l u r e (%) 1 4 4 4 . 6 0 3 5 . 1 1 7 8 . 7 L V L t h i c k n e s s ( i n ) -M o i s t u r e c o n t e n t { " ) - -II C y c l i c ( v a c / p r e s s ) " s o a k 1 D r y s h e a r s t r . ( p s i ) W o o d f a i l u r e {%) L V L t h i c k n e s s ( i n ) M o i s t u r e c o n t e n t ( % ) 9 9 9 9 1 1 5 9 . 9 0 8 9 . 7 0 1 . 6 8 1 0 3 . 9 0 -7 9 . 3 3 8 . 3 8 0 . 0 1 3 . 6 1 6 . 8 9 . 3 0 . 5 3 . 5 II II II n 2 D r y s h e a r s t r . ( p s i ) W o o d f a i l u r e (%) L V L t h i c k n e s s ( i n ) M o i s t u r e c o n t e n t { % ) 1 1 1 1 1 1 1 1 1 1 9 3 . 5 0 8 6 . 7 0 1 . 6 6 1 0 5 . 2 4 1 4 7 . 7 1 5 . 8 8 0 . 0 2 1 . 0 9 1 2 . 4 6 . 8 1 . 5 1 . 0 II it it t i 3 D r y s h e a r s t r . ( p s i ) W o o d f a i l u r e {%) L V L t h i c k n e s s ( i n ) M o i s t u r e c o n t e n t ( w ) 1 5 1 5 5 9 4 . 1 0 4 3 . 5 0 3 8 0 . 0 0 2 9 . 0 0 6 4 . 0 6 7 . 5 II D r y t e s t I B - 3 3 4 1 D r y s h e a r s t r . ( p s i ) A d j . s h e a r s t r . ( p s i ) W o o d f a i l u r e (%) L V L t h i c k n e s s ( i n ) M o i s t u r e c o n t e n t { % ) 7 7 7 7 7 1 8 3 4 . 1 0 1 6 5 7 . 9 0 8 9 . 1 0 1 . 5 6 3 . 3 4 1 8 7 . 5 7 1 4 4 . 5 7 1 3 . 0 7 0 . 0 0 0 . 2 6 1 0 . 2 8 . 7 1 4 . 7 0 . 2 7 . 6 II i i I I i i 2. D r y s h e a r s t r . ( p s i ) A d j . s h e a r s t r . ( p s i ) W o o d f a i l u r e {%) L V L t h i c k n e s s ( i n ) M o i s t u r e c o n t e n t { % ) 1 1 1 1 1 1 1 1 1 1 1 9 7 3 . 2 0 1 7 0 5 . 2 0 9 7 . 3 0 1 . 5 6 2 . 4 8 2 0 2 . 7 6 1 7 5 . 5 7 5 . 0 6 0 . 0 0 0 . 6 3 1 0 . 3 1 0 . 3 5 . 2 0 . 2 2 5 . 3 II it n I I 3 D r y s h e a r s t r . ( p s i ) A d j . s h e a r s t r . ( p s i ) W o o d f a i l u r e (%) L V L t h i c k n e s s ( i n ) M o i s t u r e c o n t e n t ( ° o ) 1 3 1 3 1 3 1 3 1 3 1 8 0 5 . 5 0 1 6 2 0 . 0 0 8 2 . 2 0 1 . 5 6 3 . 5 9 3 2 8 . 8 7 3 0 0 . 4 9 1 3 . 5 4 0 . 0 2 0 . 2 0 1 8 . 2 1 8 . 5 1 6 . 5 1 . 0 5 . 5 II C y c l i c II ( v a c / p r e s s ) s o a k 1 D r y s h e a r s t r . ( p s i ) W o o d f a i l u r e {%) L V L t h i c k n e s s ( i n ) M o i s t u r e c o n t e n t [ % ) 7 7 7 6 9 2 4 . 1 0 8 2 . 6 0 1 . 6 6 9 6 . 1 5 1 4 3 . 4 9 9 . 1 6 0 . 0 0 1 5 . 5 1 1 . 1 0 . 0 II II it n 2 D r y s h e a r s t r . ( p s i ) W o o d f a i l u r e (%) L V L t h i c k n e s s ( i n ) M o i s t u r e c o n t e n t ( % ) 1 1 1 1 1 1 1 1 1 0 7 7 . 1 0 8 8 . 4 0 1 . 6 6 1 0 0 . 7 0 9 0 . 8 9 1 0 . 2 5 0 . 0 1 1 . 6 8 8 . 4 1 1 . 6 0 . 3 1 . 7 ' It ti it ti 3 D r y s h e a r s t r . ( p s i ) W o o d f a i l u r e (%) L V L t h i c k n e s s ( i n ) M o i s t u r e c o n t e n t ( % ) 1 3 1 3 1 3 1 3 6 3 5 . 8 0 6 1 . 2 0 1 . 6 7 1 0 5 . 2 6 2 4 7 . 6 6 2 6 . 9 9 0 . 0 1 1 . 6 6 3 8 . 9 4 4 . 1 • 0 . 5 1 . 6 B l a c k c o t t o n - D r y t e s t w o o d D r y s h e a r s t r , , . . , A d j . s h e a r s t r . ( p s i ) 7 1 0 6 3 . 2 0 1 3 6 . 2 8 1 2 . 8 I B - 3 3 7 1 W o o d f a i l u r e {%) 7 9 7 . 6 0 0 . 9 0 ' . 0 . 9 L V L t h i c k n e s s ( i n ) 7 1 . 4 3 0 . 0 3 ' 2 . 1 M o i s t u r e c o n t e n t ( # ) 7 6 . 5 0 0 . 0 7 1 . 0 D r y s h e a r s t r . ( p s i ) A d j . s h e a r s t r . ( p s i ) W o o d f a i l u r e \%) L V L t h i c k n e s s ( i n ) M o i s t u r e c o n t e n t ( % ) 1 1 1 1 1 1 1 1 1 1 9 2 4 . 7 0 8 9 7 . 9 0 9 3 . 2 0 1 . 4 8 6 . 0 0 1 3 2 . 7 0 1 2 8 . 9 9 2 . 2 7 0 . 0 0 0 . 1 5 1 4 . 4 1 4 . 4 2 . 3 0 . 3 2 . 4 II It « 3 D r y s h e a r s t r . ( p s i ) A d j . s h e a r s t r . ( p s i ) W o o d f a i l u r e {%) L V L t h i c k n e s s ( i n ) M o i s t u r e c o n t e n t ( % ) 1 3 1 3 1 3 1 3 1 3 7 5 0 . 3 0 7 4 3 . 6 0 7 1 . 6 0 1 . 4 9 6 . 7 0 3 5 0 . 3 8 3 4 7 . 8 8 3 5 . 9 4 0 . 0 2 0 . 1 2 4 6 . 8 4 6 . 8 5 0 . 2 1 . 2 1 . 7 It C y c l i c ( v a c / p r e s s ) s o a k II 1 D r y s h e a r s t r . ( p s i ) W o o d f a i l u r e (%) L V L t h i c k n e s s ( i n ) M o i s t u r e c o n t e n t ( / ' ) 5 5 5 5 5 3 2 . 0 0 8 8 . 0 0 1 . 5 8 2 2 1 . 2 1 5 1 . 3 0 7 . 5 2 0 . 0 0 3 . 3 2 9 . 6 8 . 5 0 . 0 1 . 7 - •1 M 2 D r y s h e a r s t r . ( p s i ) W o o d f a i l u r e {%) L V L t h i c k n e s s ( i n ) M o i s t u r e c o n t e n t ( " ' ) 1 1 1 1 1 1 1 1 6 1 8 . 3 0 9 3 . 2 0 1 . 5 7 2 2 0 . 6 1 6 7 . 6 0 5 . 4 9 0 . 0 1 5 . 5 6 1 0 . 9 5 . 9 0 . 6 2 . 5 M II • ! i i 3 D r y s h e a r s t r . ( p s i ) ' W o o d f a i l u r e {'/,) L V L t h i c k n e s s ( i n ) M o i s t u r e c o n t e n t ^ , ) . 1 4 1 4 1 4 1 4 3 6 3 . 2 0 5 8 . 9 0 2 1 8 . 5 6 _ 2 4 8 . 1 2 3 9 . 1 9 1 0 . 1 6 6 8 . 3 6 6 . 6 4 * 7 127 TABLE 31 - Continued VI™A P h o n n U r Sample Standard Coefficient spelies A 9 - g " " g l ^ 1 0 Section Variable sile Mean deviation o f ^ . i a -Black . . cotton- Dry test wood IB-334 Dry shear s t r . (ps i ) 7 1335.90 106.83 8.0 Adj.shear s t r . (ps i ) 7 1297.10 102.85 7.9 Wood fai lure (%) 7 98.10 0.69 0.7 LVL thickness (in) 7 1.49 0.01 0.8 Moisture content^) 7 5.79 1.66 11.4 it II Dry shear s t r . (ps i ) r .(psi) Wood fa i lure (%) Adj.shear s t r . n II tt Cycl ic (vac/press) soak 7.5 7.5 0.7 0.3 3.3 9 1040.90 78.08 9 963.30 72.47 9 99.70 0.71 LVL thickness (in) 9 1.47 0.01 Moisture content(^) 9 4.52 0.15 Dry shear s t r . (ps i ) 13 896.70 280.81 Adj.shear s t r . (ps i ) 13 875.20 273.64 Wood fa i lure (%) 13 88.10 24.63 LVL thickness (in) 13 1.48 0.01 Moisture content^) 13 6.21 0.12  Dry shear s t r . (ps i ) 7 710.30 28.67 4.0 Wood fa i lure {%) 7 80.70 9.14 11.3 LVL thickness (in) 7 1.58 0.00 0.0 Moisture content(^) 7 209.69 4.48 2.1 31.3 31.3 28.0 0.5 1.9 Dry shear s t r . (ps i ) 9 535.60 46.96 8.8 Wood fa i lure (%) 9 90.90 9.70 10.7 LVL thickness (in) 9 1.58 0.01 0.6 Moisture content.(^) 9 209.09 4.57 2.2 n i t II Dry shear s t r . (ps i ) 13 337.80 132.78 Wood fa i lure (%) 13 78.90' 18.35 LVL thickness (in) 13 1.59 0.12 Moisture content(^) 13 214.72 4.93 White spruce Dry test Dry shear s t r . (ps i ) (psi) Wood fa i lure {%) Adj.shear s t r . 6 990.00 153.77 6 1041.50 162.21 6 89.20 6.88 LVL thickness (in) 6 1.50 0.01 Moisture content^) 6 8.73 , 0.09 39.3 23.2 1.0 2.3 15.5 15.6 7.7 0.3 1.0 n I I Dry shear s t r . (ps i ) 12 Adj.shear s t r . (ps i ) 12 Wood fa i lure (%) 12 LVL thickness (in) 12 Moisture content{%) 12 1147.00 1177.00 94.20 1.48 7.91 218.36 218.94 8.96 0.02 . 0.24 19.0 18.6 9.5 1.2 3.1 it II II Dry shear s t r . (ps i ) 12 : . (psi) 12 Wood fa i lure {%) 12 Adj.shear s t r . 1019.40 1065.70 92.20 1.49 8.51 139.75 147.19 7.07 0.00 0.12 13.7 13.8 7.7 0.0 1.4 LVL thickness (in) 12 Moisture content(%) 12 Dry shear s t r . (ps i ) 6 553.20 1. 165.65 29.9 Wood fa i lure {%) 6 74.00 • 15.49 20.9 LVL thickness (in) 6 1.57 0.02 0.1 Moisture content[%) 6 187.17 ' 7.18 3.8 Cycl ic (vac/press) soak Dry shear s t r . (ps i ) 12 783.90 129.46 16.5 Wood fa i lure {%) 12 87.50 11.14 12.7 LVL thickness (in) 12 1.57 0.02 1.2 Moisture content^) 12 177.57 6.89 3.0 II I I it Dry shear str .( .psi , 12 685.9 Wood fa i lure (%) 12 83.2 LVL thickness .(in) 12 1.586 Moisture content("o) 12 177.57 170.07 12.16 0.010 6.890 24.8 14.6 0.6 3.9 Sections 1, 2 and 3 correspond to segments of continuous LVL which were (a) single-pressed portion of the starter board, (b) double pressed 24-inch portion of continuous LVL and (c) section containing end jo in ts which protruded out of platens for the duration of one press cycle . 128 TABLE 32 G l u e l i n e temperature i n continuous LVL at various p o i n t s along the b o a r d 8 Species P l a t e n pres-sure (p s i ) Recorder Channel (points) I n i t i a l temper-ature (o F)b. F i n a l temper-ature ( 0 F ) C T o t a l change i n temp-ature(°F) Time to f i n a l tempera- , ture(min) Factor Xe (°F/min) Phenol-formalde-hyde glue brand Black Cottonwood 100 1 2 3 4 5 6 7 8 84 133 89 83 144 77 78 79 230 294 210-182 282 207-226 232 146 161 121 99 138 130 148 153 22 22 22 22 21 21 21 21 6.64 7.32 5.50 4.50 6.57 6.19 7.05 7.29 IB-337 Sugar maple 275 1 2 3 4 5 6 7 8 81 107 88 88 132 80 81 81 240 295 226 139 294 • 136 191 246 149 188 138 51 162 56 110 165 19 19 19 19 18 18 18 18 7.84 9.89 7.26 2.68 9.00 3.11 6.11 9.17 „ White spruce 100 1 3 4 5 6 7 8 74 82 77 119 69 69 69 240 166 135 253 108 135 210 166 84 58 134 39 66 141 19 19 19 18 18 18 18 8.74 4.42 3.05 7.44 2.17 3.67 7.83 » Black Cottonwood 100 1 2 3 4 5 6 . 7 8 78 90 88 73 136 73 73 74 226 272 239 211 281 217 219 221 148 182 151 138 145 144 146 147 22 22 22 22 21 21 21 21 6.73 8.27 6.86 6.27 6.90 6.86 6.95 7.00 IB-334 tf B fl 1 * 1  Sugar maple 275 1 2 3 4 5 6 7 8 82 108 86 84 141 77 77 78 240 288 219 129 286 162 202 233 158 180 133 45 145 85 125 155 17 17 17 17 16 16 , 16 16 9.29 10.59 7.82 2.65 9.06 5.31 7.81 9-69 1  II tl 1  0 II • d Four p a i r s of points i n the g l u e l i n e were chosen to monitor temperature of c e n t r a l g l u e l i n e (CGL) and outer g l u e l i n e (OGL) of the continuous board. P o i n t s 1 and 2 were CGL and OGL of LVL and were located at the geometric centre of platens. 1 They were als o w i t h i n " s t a r t e r board." Points 8 and 5 were CGL and OGL located two inches from platen edge, and hence were w i t h i n s e c t i o n 2. Points 7 and 3 were CGL and OGL one inch outside p l a t e n , while 6 and 4 were CGL and OGL two inches outside p l a t e n . ^Temperature when platens at t a i n e d f u l l pressure except i n channels 5 - 8 where the i n i t i a l temperature was monitored one minute l a t e r owing to instrument l i m i t a t i o n . c F i n a l temperature of CGL was 240°F except i n black cottonwood. ^Period over which temperature was monitored. Factor X was c a l c u l a t e d by d i v i d i n g the change i n CGLT by time of chang TABLE• 33 C y c l i c vacuum/pressure/d ry delamination of LVL Continuous LVL Board Se c t i o n 1 2 3 Wood species Glue D e 1 a m i n a t i o n ( % ) Remarks Black c o t t o n -wood IB-337 0 0.6 7 Fiv e specimens f a i l e d i n s e c t i o n 3. Sugar maple II 9.3 2.8 58 S i x , two, and a l l 12 specimens f a i l e d i n sect i o n s 1, 2 and 3, r e s p e c t i v e l y . White spruce it 0 0 0 No delamination Black c o t t o n -wood IB-334 0 0 4.8 Only the f i r s t two specimens f a i l e d , scor-ing 32 and 35% respec-t i v e l y . Sugar maple ii 1.8 1.2 24.3 Only one specimen f a i l e d i n s e c t i o n 2, while seven f a i l e d i n s e c t i o n 3. TABLE 34 B o i l / d r y / b o i l delamination of PF IB-334 bonded LVL Continuous LVL Board Section 1 2 3 Wood species D e l a m i n a t i o n ( % ) Remarks Black cottonwood 0 0 2.8 Only the f i r s t two specimens i n s e c t i o n 3 f a i l e d , s c o r i n g 23 and 14%, respec-t i v e l y Sugar maple 0 0 27.5 Ten specimens f a i l e d i n s e c t i o n 3. co o TABLE 35 Comparison of shear strength of phenolic glue IB-337-bonded LVL with published data on s o l i d sawn lumber 3 Shear stren g t h of LVL ( DSi) Shear strength of s o l i d sawn lumber ( o s i ) Shear s t r e n g t h of LVL as % of s o l i d lumber Dry t e s t b Adjusted t o 1% MC value-Green P i A i r dr; j b l i s h e d /^Green A i r dry adjusted to 7% MC value Adjusted shear strength Green shear strength Broadleaf maple 1639 (--) - 594 1765 1265 2030 - 47 Black cottonwood 1227 (5.05) 1156 566 1157 770 1331 87 74 Sugar maple 3350 (3.59) 3008 1368 2424 1615 2788 108 85 Strength and r e l a t e d p r o p e r t i e s of woods grown i n Canada (Kennedy, 1965). Kennedy 1 study i n v o l v e d l a r g e samples of specimens from s e v e r a l t r e e s sampled over a l a r g e geographic reg i o n whereas the LVL was made from small samples of specimens from a few t r e e s obtained from a s i n g l e l o c a t i o n . ^ F i g u r e s i n parentheses r e f e r to average moisture content at t e s t . These f i g u r e s were not used f o r the adjustment t o 1% MC value. Adjustment was done f o r each specimen. A i r dry c o n d i t i o n was given as approximately 12% moisture content. Approximate adjustment was done using a conversion f a c t o r .of 3% f or increase or decrease i n shear stren g t h f o r each decrease or increase of moisture content from observed t o adjusted moisture content (USDA Forest S e r v i c e , 1955). 132 .TABLE 36 Performance of continuous LVL c e n t r a l g l u e l i n e a c c o r d i n g t o PS 56 - 73 Wood Species Aging Glue S e c t i o n A d j u s t e d shear s t r e n g t h of LVL as percent of a s o l i d lumber e q u i v a l e n t Wood f a i l u r e Comment Sugar maple Dry t e s t PF IB-337 i c 73 95 F a i l e d H it 1  2 79 94 F a i l e d ti n " 3 37 44 F a i l e d it C y c l i c ( v a c / press) soak II 1 72 90 F a i l e d it « II 2 74 87 F a i l e d ti II II 3 37 44 F a i l e d n Dry t e s t PF IB-334 1 59 89 F a i l e d ii II ti 2 61 97 F a i l e d ti n II 3 58 82 F a i l e d - C y c l i c ( v a c / press) soak II 1 57 83 F a i l e d n it II 2 67 88 F a i l e d n II II 3 39 61 F a i l e d B l a c k c o t t o n -wood Dry t e s t PF IB-337 1 107 98 Passed ii it 2 91 98 Passed n " II 3 75 72 F a i l e d it it C y c l i c (Vac/ pr e s s ) soak II 1 2 95 110 88 93 Passed Passed II " it 3 65 59 F a i l e d II Dry t e s t PF IB-334 1 131 98 Passed " " n 2 97 100 Passed II " II 3 88 88 Passed " C y c l i c (Vac/ p r e s s ) soak " 1 127 81 Passed II " it 2 96 91 Passed II " n 3 63 79 F a i l e d White Spruce Dry t e s t PF IB-337 1 92 89 Passed II " tl 2 104 94 Passed ti " II 3 94 92 Passed II C y c l i c (Vac/ P r e s s ) soak II 1 83 74 F a i l e d it II 2 117 88 Passed II " II 3 102 83 Passed b Shear s t r e n g t h p a r a l l e l t o g r a i n p u b l i s h e d by Kennedy (1965) adj u s t e d t o t h e i r Tj<> MC e q u i v a l e n t . Shear s t r e n g t h a f t e r c y c l i c (vacuum/ pressure) soak was regarded as being e q u i v a l e n t t o the green v a l u e s . b F a i l e d + denotes t h a t a s e c t i o n f a i l e d e i t h e r of the s p e c i f i c a t i o n f o r shear s t r e n g t h and t h a t f o r wood f a i l u r e . S e c t i o n 1 corresponds t o segment of LVL s t a r t e r board which was s i n g l e -pressod, s e c t i o n 2 was double-pressed and s e c t i o n 3 was tho segment c o n t a i n i n g tho s t e p - j o i n t s which protruded out of p l a t e n s d u r i n g one press c y c l e . 133 10 FIGURES VENEER ARRANGEMENTS IN CONTINUOUS LVL CHANNELS 1 and 2 ARE LOCATED AT GEOMETRIC CENTRE OF PRESS PLATENS 5 and 8 ARE TWO INCHES FROM PLATEN EDGE 3 and 7 ARE ONE INCH OUTSIDE PLATEN EDGE A and 6 ARE TWO INCHES OUTSIDE PLATEN ARROWS SHOW STEPS PROTRUDING OUT OF PLATENS. (Hoi drown lo scale) . , -J 1 1 8 7 6 ^ 2 5 3 4 f g U r e 2 LOCATION OF THERMOCOUPLES IN GLUELINES OF CONTINUOUS LVL C3 •48 Figure 3 A 16-FOOT CONTINUOUS LVL BOARD L E °  E " ° TT7-X \ / / / \ THE SUCCESSIVE PLATEN CLOSURES ^— PORTIONS DOUBLE-PRESSED OWING TO OVERLAP OF PLATEN ON PREVIOUSLY PRESSED PORTIONS ARE MARKED C2.C3.C4 and C5, RESPECTIVELY. 137 Legend: Arrows point to panels which were not constructed. In such cases, measurements on panels in previous tests were used. CGLT refers to central glueline temperature. MPRG refers to modified phenol-resorcinol glue. Test Adequate gluespread Effect of platen Adequate curing temperature BROADLEAF MAPLE Spread (lb/MSGL) 27.5 Panel No. 1 Platen temp.(°F) Panel No. CGLT (°F) Panel No. Effect of pressure Platen pressure (psi) Panel No. Pressing conditions other than factors tested  42.5 200 p s i , 233°F CGLT and A 300°F platen temperature 200 p s i , 233°F CGLT, Gluespread of 42.5 l b / MSGL Platen temperatures of 300, 350 and 400°F, respect ively , gluespread of 42.5 lb/MSGL CGLT of 240OF, gluespread of 42.5 lb/MSGL BLACK COTTONWOOD Adequate gluespread Spread (lb/MSGL) Panel No. 30 1,2 37.5 3,4 42.5 / 69 p s i , CGLT of 240°F and platen temperature of 350°Fa Adequate pressure Platen pressure (psi) Panel No. 100 3,4 Gluespread of 42.5 l b / MSGL, CGLT of 240°F Bond qual i ty with MPRG Aging Panel No. SUGAR MAPLE, Dry 1 CVPS 2 100 p s i , gluespread of 42.5 lb/MSGL and CGLT of 180OF+ Adequate gluespread Spread (lb/MSGL) Panel No. . 30 1,2 37.5 3,4 42.5 ,5^6, 250 p s i , CGLT of 240°F Adequate pressure Platen pressure (psi) Panel No. 2 5 0 / 1 ^ ' 275 3,4 Gluespread of 42.5 l b / MSGL, CGLT of 240°F Effect of double-pressing Press time/glue (min) PF IB-337 Panel No. 20 1,2 40 3.4 Gluespread 42.5 lb/MSGL 275 ps i and 350°F platen temperature Effect of double-pressing control Press time/glue (min) PF IB-334 Panel No. 20 1.2 40 3.4 II II II Adequate gluespread with MPRG Spread (lb/MSGL) Panel No. 37.5 1.2 42.5 1.2 275 p s i , CGT 180°F+ FIGURE 4. SMALL PANELS CONSTRUCTED FOR THE VARIOUS TESTS a I n subsequent tes ts , platen temperature was at 350°F. DENTED ARROWS SHOW FOUR-INCH STRIPS FROM WHICH THREE 4X4 SPECIMENS (STRIPED) WERE SAWN (Not drawn lo scale) 24.5 24.5 A 3" 4" 4" 4" 4" 4" 2" 19 4" 19 5" 4" 4" 4" 4" 4' 2' 25" BLACK COTTONWOOD 27" SUGAR MAPLE Figure 5 CUTTING FOUR-INCH STRIPS FROM FULL SIZE VENEERS CO DENTED ARROWS SHOW THE VENEER QUALITY SPECIMENS. (Not drawn to the scale ) 16" 16" 16" 52 42 50 4 " 4" 20" BLACK COTTONWOOD 20" SUGAR MAPLE 20" WHITE SPRUCE Figure 6 CUTTING OF VENEER QUALITY SPECIMENS FROM LARGE VENEER SHEETS FOR THE COTINUOUS LVL End board veneer pieces 30" 140 b J Hi M : c *• 12" d »• e *-X. ^ _ T ' Starter board veneers pieces Figure 7 CUTTING THE STARTER AND END BOARDS FROM ONE SET OF FULL LENGHT V4 INCH THICK VENEERS. L E G E N D LENGHT OF STARTER BOARD ( FIGURES ARE IN INCHES) LAMINATES VARIED AS SHOWN BELOW a b c d e f BLACK COTTONWOOD 22 28 34 40 46 52 SUGAR MAPLE 12 18 24 30 36 42 WHITE SPRUCE 20 26 32 38 44 50 141 3 2 0 - | 2 8 C H 3 0 0 ° F 240 + 2 4 0 ° F 2 3 3 °F . — OUTER GLUELINE CENTRAL GLUELINE 2 0 0 H 160H / / / / I P L A T E N TEMPERATURE P L A T E N P R E S S U R E G L U E S P R E A D = 3 0 0 ° F = 200 psi = 42.5 l b / M S G L G L U E Phenol - formaldehyde ( I B - 3 3 7 ) UJ c LU Q. s Ul ui W 8 0 -_i UJ z> -i o I i I 4 0 -o 10 I— 20 i — 30 4 0 50 P R E S S T IME (MIN.) Figure 8 T E M P E R A T U R E RISE AT GEOMETRIC C E N T R E OF INNER AND OUTER GLUEL INES OF B R O A D L E A F M A P L E LAMINATED VENEER L U M B E R . 142 250-22CH Sml^-X Sp1 CRITICAL CURING TEMPERATURE 2 4 0 °F Cw1 Cw7 Cw3 Sm - SUGAR MAPLE Sp - WHITE SPRUCE Cw - COTTONWOOD 1 IS THE CENTRAL GLUELINE TEMPERATURE MONITORED FROM GEOMETRIC CENTRE OF THE PRESS PLATENS. REPRESENTS CENTRAL GLUELINE TEMPERATURE MONITORED FROM THE STEPPED JOINT ONE INCH OUTSIDE THE PLATENS. OUTER GLUELINE TEMPERATURE EQUIVALENT OF 7 l 20 I— 25 P R E S S TIME (MIN) Figure 9 T E M P E R A T U R E R I S E A T T H R E E C R I T I C A L P O I N T S IN T H E L V L L A Y U P I N C O N T I N U O U S B O A R D P R O D U C T I O N P R O C E S S 143 C/3 O •X H O H t/1 to Platen Edge O ' o o A A .A 2 A Section Section 1 2 •- t 1 0 . 0 1 1 7 . 0 1 4 - 0 Legend: j ^ Section l(Pressed once dur-^ Ing manufacture) Section 2(Pressed twice dur» ing manufacture) ° Section 3 (Stepped joints sticking outside platens during f i r s t press cycle and pressed during the second press cycle) Strength value of dry test specimens. Strength value of dry test specimens adjusted to 7% moisture content equivalent. Strength value of specimens aged by cyclic (vacuum/pressure) soak. 21 .0 2 8 . 0 35.0 CONSECUTIVE TWO-INCH BLOCKS ALONG LVL LENGTH FIGURE 1 0 BLACK COTTONWOOD LVL STRENGTH QUALITY RESPONSE TO CONTINUOUS LAMINATING PROCESS USING PHENOL FORMALDEHYDE GLUE 1 B 3 3 7 1 4 4 Legend : A Section 1 (Pressed once during manufacture) t Section 2 (Pressed twice during manufacture) o Section 3 (Stepped jo i n t s s t i c k i n g outside platens during f i r s t press cycle and pressed during the second press cycle) Strength value of dry test specimens. .... Strength value of specimens aged by c y c l i c fy acuum/pressure) s o a k . {Section 1 0.0 Section 2 7.0 1^.0-'Platen Edge o 3 O ' a - 0 - 0 • % 8 - : "~1 21 .0 Section 3 —I 28.0 3r).0 CONSECUT I.VK TWO-INCH BLOCKS AI.ONC LVL LKNGTH FIGURE 11. BLACK COTTONWOOD LVL STRENGTH QUALITY RESPONSE TO CONTINUOUS LAMINATING PROCESS USING PHENOL FORMALDEHYDE GLUE 1B337 145 P l a t e n Edge Legend: A S e c t i o n 1 ( P r e s s e d once dur-i n g manufacture) t S e c t i o n 2 ( P r e s s e d twice d u r -i n g manufacture) o S e c t i o n 3 (Stepped j o i n t s s t i c k i n g o u t s i d e p l a t e n s d u r i n g f i r s t p r e s s c y c l e and pres s e d d u r i n g the second p r e s s c y c l e ) S t r e n g t h v a l u e of dry t e s t specimens. S t r e n g t h v a l u e of dry t e s t specimens a d j u s t e d to 7% mo i s t u r e content e q u i v a l e n t . S t r e n g t h v a l u e of specimens aged by c y c l i c (vacuum/pressure) soak. 7 . 0 1 4 . 0 2 1 . 0 2 8 . 0 CONSECUTIVE TWO-INCH BLOCKS ALONG LVL LENGTH 3 5 . 0 FIGURE 12. BLACK COTTONWOOD LVL STRENGTH QUALITY RESPONSE TO CONTINUOUS LAMINATING PROCESS USING PHENOL FORMALDEHYDE GLUE 1B334 Legend : 146 A, Section l(Pressed once during manufacture) t Section 2 (Pressed twice during manufacture) o Section 3 (Stepped j o i n t s s t i c k i n g outside platens during f i r s t press cycle a n d pressed during the second press cycle) Strength value of dry test specimens. .... Strength value of specimens aged by c y c l i c ( V a c u u m/pressure) s o a k . Platen Edge o o o -\ oo 2 • J < O o o 3 o CM o o Section 1 Section 2 0.0 — f 7.0 oV P/,' ; wo o V I I 1 Section 3 " T 14.0 21.0 28.0 CONSECUTIVE TWO-INCH BLOCKS ALONG LVL LENGTH 35.0 FIGURE 13. BLACK COTTONWOOD LVL STRENGTH QUALITY RESPONSE TO CONTINUOUS LAMINATING PROCESS USING PHENOL FORMALDEHYDE GLUE 1B334 147 Legend: A S e c t i o n 1 ( P r e s s e d once d u r i n g manufacture ) t S e c t i o n 2 (Presse d twice d u r i n g manufacture) o S e c t i o n 3 (Stepped j o i n t s s t i c k i n g o u t s i d e p l a t e n s j l u r i n g f i r s t p r e s s c y c l e and p r e s s e d d u r i n g the second p r e s s c y c l e ) S t r e n g t h v a l u e ot dry t e s t specimens. _Strength v a l u e of dry t e s t specimens a d j u s t e d to 7% moisture content e q u i v a l e n t . S t r e n g t h v a l u e of specimens aged by c y c l i c (vacuum/press-ure soak. P l a t e n Edge 0.0 7.0 14.0 21.0 28.0 CONSECUTIVE TOO-INCH BLOCKS ALONG LVL LENGTH 35.0 FIGURE 14. SUGAR MAPLE LVL STRENGTH QUALITY RESPONSE TO CONTINUOUS LAMINATING PROCESS USING PHENOL FORMALDEHYDE GLUE 1B337 143 Legend : A S e c t i o n t S e c t i o n o S e c t i o n 1 ( P r e s s e d once d u r i n g manufacture) 2 ( P r e s s e d twice d u r i n g manufacture) 3 (Stepped j o i n t s s t i c k i n g o u t s i d e p l a t e n s , d u r i n g f i r s t p r e s s c y c l e and p r e s s e d d u r i n g the second p r e s s c y c l e ) S t r e n g t h v a l u e of dry t e s t specimens a d j u s t e d to 7% moisture content e q u i v a l e n t S t r e n g t h v a l u e of specimens aged by c y c l i c (Vacuum/pressure) soak. 1 A, o oo no -3 < Q O O O - 3 -O CN o o P l a t e n Edge S e c t i o n 1 0.0 ~ ~ 1 — 7.0 S e c t i o n 2 O-O O 0 - O - » 14.0 21.0 28.0 CONSECUTIVE TWO-INCH SLOCKS ALONG LVL LENGTH 35.0 FIGURE 15. SUGAR MAPLE LVL STRENGTH QUALITY RESPONSE TO CONTINUOUS LAMINATING PROCESS USING PHENOL FORMALDEHYDE GLUE 1)5337 Legend: 149 A Section 1 (Pressed once during manufacture) t Section 2 (Pressed twice during manufacture) o Section 3 (Stepped j o i n t s s t i c k i n g outside platens during f i r s t press cycle and pressed during the second press cycle) Strength value o f dry t e s t specimens. Strength value of dry t e s t specimens adjusted to 7% moisture content equivalent. ... Strength value of specimens aged by c y c l i c (vacuum/pressure) s o a k . CONSECUTIVE TWO-INCH BLOCKS ALONG LVL'LENGTH FIGURE 16. SUGAR MAPLE LVL STRENGTH QUALITY RESPONSE TO CONTINUOUS LAMINATING PROCESS USING PHENOL FORMALDEHYDE CLUE 1B334 150 Legend : L S e c t i o n 1 ( P r e s s e d once d u r i n g manufacture) t S e c t i o n 2 ( P r e s s e d twice d u r i n g manufacture) o S e c t i o n 3 (Stepped j o i n t s s t i c k i n g o u t s i d e p l a t e n s d u r i n g f i r s t p r e s s c y c l e and p r e s s e d d u r i n g the second p r e s s c y c l e ) S t r e n g t h v a l u e of dry t e s t specimens. .... S t r e n g t h v a l u e of specimens aged by c y c l i c 0/ acuum/pressure)soak. S e c t i o n 1 •P l a t e n Edge S e c t i o n 2 I •I ?/ i \ 4 I \ \ \ p.jO » I. I . v. v • o ; S e c t i o n 3 0.0 7.0 14.0 21.0 28.0 35.0 CONSECUTIVE TWO-INCH BLOCKS ALONG LVL LENGTH FIGURE 17. SUGAR MAPLE LVL STRENGTH QUALITY RESPONSE TO CONTINUOUS LAMINATING PROCESS USING THENOL FORMALDEHYDE GLUE 1B334 1 5 1 P l a t e n Edge Legend : A S e c t i o n l ( P r e s s e d once dur-i n g manufacture) t S e c t i o n 2 (Pressed twice d u r i n g manufacture) o S e c t i o n 3(Stepped j o i n t s s t i c k i n g o u t s i d e p l a t e n s d u r i n g f i r s t p r e s s c y c l e and pr e s s e d d u r i n g the second p r e s s c y c l e ) S t r e n g t h v a l u e o f dry t e s t specimens. S t r e n g t h v a l u e of dry t e s t specimens a d j u s t e d to 7% moisture content e q u i v a l e n t . S t r e n g t h v a l u e o f specimens aged by c y c l i c (vacuum/pressure) soak. CONSECUTIVE TWO-INCH BLOCKS ALONG LVL LENGTH FIGURE 18. WHITE SPRUCE LVL STRENGTH QUALITY RESPONSE TO CONTINUOUS LAMINATING PROCESS USING PHENOL FORMALDEHYDE GLUE 1B337 152 Legend : A Section 1 (Pressed once during manufacture) t Section 2 (Pressed twice during manufacture) o Section 3 (Stepped jo i n t s s t i c k i n g outside platens during f i r s t press cycle and pressed during the second press cycle) Strength value of dry test specimens. .... Strength value of specimens aged by c y c l i c (V acuum/pressure)soak. Platen E d g e • J M 25 n o o 0 . 0 7 . 0 1 4 . 0 2 1 . 0 2 8 . 0 CONSECUTIVE TWO-INCH BLOCKS ALONG LVL LENGTH FIGURE 19. WHITE SPRUCE LVL STRENGTH QUALITY RESPONSE TO CONTINUOUS LAMINATING PROCESS USING PHENOL FORMALDEHYDE GLUE 1B337 153 11 APPENDICES 154 Environment Environnement our me NOUB dossier 361-3-1-1 Canada Canada Canadian F o r e s t r y S e r v i c e , Eastern Forest Products Lab, Montreal Road, Ottawa K1A-0W5. August 24, 1973. Dr. W.V. Hancock, Western Forest Products Laboratory, 6620 N.W. Marine D r i v e , Vancouver 8, B.C. Dear B i l l : I f i r s t wish to thank you f o r the copies of your r e p o r t VP-X-109 on cedar veneer and the use of the steam k n i f e . We found t h i s r e p o r t to be very i n t e r e s t i n g . I wish to inform you that today we were s u c c e s s f u l i n p e e l i n g 1/4 i n c h hard maple veneer which should be s u i t a b l e f o r the manufacture o f laminated-veneer lumber (LVL). The c u t t i n g c o n d i t i o n s were: Species: acer saccharum (Spec, g r a v i t y 0.66) Thickness: 0.272" (green) H o r i z . gap: 0.260" V e r t , gap: 0.060" Kn i f e angle (24" diam) 89°00' K n i f e angle (9" diam) 88°00' Kn i f e b evel 20° Bar angle 14° B o l t temperature 200°F -Veneer th i c k n e s s v a r i e d from 0.277 i n . to 0.283 i n The average depth.of roughness was 0.008 i n . and the maximum about 0.020 i n . j l a t h e check p e n e t r a t i o n v a r i e d from 50 to 75% of the t h i c k n e s s of veneer. Some sheets were broken r i g h t through, coming o f f the l a t h e ; also more breakage should be expected from handling dry veneer. A l l the sheets were s l i g h t l y corrugated; however, we do not f e e l t h a t the c o r r u g a t i o n would i n t e r f e r e w i t h g l u i n g . This q u a l i t y , o f course, i s that of veneer peeled under l a b o r a t o r y c o n d i t i o n s . We are now ready to p e e l the 600 square f e e t of veneer r e q u i r e d f o r your p r o j e c t . We hope to f i n d a l l the m a t e r i a l i n the four logs we now have i n storage; i f not, we would have to t r a v e l 100 miles to the nearest m i l l which can supply us. The dimensions of these logs are: - 2 - 155 Log No Length Butt diam. Top diam. 7 sound 2 sound 3 sound 4 some decay and r i n g shake 11' 8 1 6' 8' 6" 18" 17" 12" 11" 17" 15" 11" 10" On the b a s i s of these dimensions can you t e l l us the l e n g t h and width of the sheets you r e q u i r e . The maximum l e n g t h we can p e e l i s 4 f e e t but would, p r e f e r not to exceed 40 inches. Should we get more breakage than expected, what i s the minimum width you can accept? F i n a l l y what should be the moisture content of the dry veneer? As f o r the f i n a n c i a l side of t h i s e n t e r p r i s e , only the f r e i g h t (approx. $50) w i l l be charged to your Laboratory. Yours s i n c e r e l y , JW2S 1973-W E S T E R M F O R E S T P R O D U C T S ' . . A B O R A T O R Y V A ; - . C O U V t U S, B.C. PIL2: "%3-O-Q | D A T ; i IN'IT. 0. F e i h l and V. Godin Veneer § Plywood Group, Wood Production D i v i s i o n APPENDIX 1(b) 1 5 6 v >k<" V «,« /Vo ,1 U ) ^ _ 2_. j> Tute 5o^A TU&ASUM> J/^yr-^ S lsjmJ:<, iXy-vliv. t S U.^JLA <> " ... ' D<^ A sUi- /ii.) _ (Sui _ ( i u t M A 2 4 2 I 5" 2oF 1° Z ^ f O A Ay 24 r -Io._ii£ 4Ho cfj) I ^ A Q J A M . i T _ 4o r L ^ F. i A _ i * J D 55 H o 0 I 3D ^ A/ io 46/t/_ 73 1 s U i A , I Le$e. ?Ui>U. _ tvvir.\;.«v*b-_. fpyl^S\R/\*"^ Q ^ i i i fi d , — v ^ - i i ci; 0 p 1 5 7 1 A . A . 2 c) O l j 5 Z 5 A A 2')o 2J$ 2JfJ_ AA± AAAl. 2<iC z A l . l$ i. U 4 AAA A I L j ? y n i jj.± z j j _ J A < L 15 \L i AAA 2JA ; 1J4 Vo ^AAl A Ac) _ . 2 2_n. q ^J ZJO ZJJ ?<^3 21 J_ AA i 7j 2JA_ 2XA UtAL i J A. AAA. IDA AAJ ±o_ Z y_rj l J 2JJ Z J L S lAo AAA J o J l J I Jo_ t l x _ U J K _ 2 $o_ 2 yz 2Jo zj A .6 2L_ _ lib 2Ji 2J[ Ljo_ 10 2 7 c; z i s 2<j a 2 J ?_ APPENDIX ' l ( c ) 1 5 8 SEP 3 1974 CFS WFPL VCR CFS FPL OTT SEPT 3/74 DR HANCOCK DRYING SCHEDULE FOR ONE QUARTER INCH SUGAR MAPLE VENEER INITIAL MC - 90 PERCENT FINAL MC = 2 PERCENT TEMP = 325 F . ANXX AIR VELOCITY = 900 FT/MIN VENEER UAS PASSED TWICE TRHOUGH THE TWO ZONES OF THE DRYER FOR A PERIOD OF 30 MIN EACH PASS OLIVER HEIHL FEIHL CFS FPL OTT * CFS WFPL VCR EV 159 APPENDIX I I Pe e l i n g parameters fox black cottonwood b o l t s Thickness set: 0.273 i n . V e r t i c a l gap: 0.118 i n . Knife ( p i t c h ) angle* (at b o l t diameters greater than 12 i n ) : 90° 00' Knife ( p i t c h ) angle (at 12 i n . b o l t diameters and l o w e r ) : 89° 30 1 Knife angle: 20° 50' Knife t h i c k n e s s : 5/8 i n . Knife hardness 56 Rockwell hardness P e e l i n g speed: . 150 fpm. One of the b o l t s was peeled at 89° 50* APPENDIX I I I K i l n schedule used for drying black cottonwood used i n t h i s study 160 161 APPENDIX 'lV(a) Glue mix and Mixing Sequence f o r a F i v e - G a l l o n Bucket of PF IB-337 9 Water 890 IB-337 6240 N o r p r o f i l ' 1340 Wheat f l o u r 445 (mix f o r 5 min.) Soda ash 356 (mix f o r 30 min.) IB-337 8900 Water 1780 19,951 Other i n f o r m a t i o n supplied by the manufacturer: PF s o l i d s 26.6% Tota l s o l i d s 41.1% APPENDIX IV(b) Glue Mix and Mixing Sequence f o r a F i v e -G a l l o n Bucket of PF IB-334 IB-334 Plyophen 5872 Water 1781 N o r p r o f i l 1444 Wheat f l o u r 963 Soda ash 409 (mix f o r 15 min. 4000 rpm Bowers mixer ) IB-334 Plyophen 7702 Water 1829 20,000 Other i n f o r m a t i o n : PF s o l i d s 23.8% Wheat f l o u r 4.8% Tot a l s o l i d s 43.9% APPENDIX V 163 August 9 t h , 19 74 \ Mr. A. A f o l a y a n , c/o Dr. W. Hancock, F o r e s t P r o d u c t s L a b o r a t o r y , Dear Mr. A f o l a y a n : T h i s l e t t e r i s i n response t o your t e l e p h o n e e n q u i r y f o r i n f o r m a t i o n on t h e r e l a t i v e s p e e d s - o f - c u r e o f IB-334 Plyophen and IB-3 3 7 P l y o p h e n . D u r i n g l a b . development o f t h e s e r e s i n s , our s p e e d - o f - c u r e t e s t i n v o l v i n g p r e s s time r e d u c t i o n s i n d i c a t e d t h a t IB-337 had a n o t i c e a b l e f a s t e r cure r a t e t h a n r e s i n IB-334. The assembly time t o l e r a n c e o f b o t h r e s i n s were e q u i -v a l e n t i n t h e l a b . IB-3 37 accounts f o r o n l y a s m a l l p o r t i o n o f our p h e n o l i c s a l e s and t h e customers u s i n g i t have not f u l l y u t i l i z e d i t s f a s t c u r e c a p a b i l i t i e s . Yours v e r y t r u l y , REICHHOLD CHEMICALS LIMITED W. C. A i n s l i e , Wood Lab. Manager WCA/jm P.O. Box 130 • Port Moody • British Columbia • Telephone: 604-939-1181 • TWX: 610-926-5096 164 203-1847 WEST BROADWAY, VANCOUVER, B.C., CANADA. I TELEPHONE (604) 736-3511. TELEX 04-55286. CABLE "NORINCATE" . - - -V6J 1Y6 *' M a r c h 2 7 , 1 9 7 4 D e a r A d e m o l a : P l e a s e f i n d e n c l o s e d t h e o r i g i n a l l i s t o f m a c h i n e r y f o r y o u r L V L p l a n t s t u d y . We h a v e g i v e n c u r r e n t b u d g e t p r i c e s f o r t h e e q u i p m e n t a n d we h a v e a l s o e n c l o s e d d e s c r i p t i v e l i t e r a t u r e f o r some o f t h e m a j o r e q u i p m e n t i n p l y w o o d a n d s a w m i l l p l a n t s . T r u s t i n g t h i s w i l l a i d y o u i n y o u r s t u d i e s , I r e m a i n , Y o u r s t r u l y , J o h n I n g r a m . J I : s d E n c l o s u r e s j^ftj} 2 8 1974 FORE WESTERN. ST PRODUCTS LABORATORY VANCOUVER is, B. C. F ILE : DATfc -.15 i O j :N1T. j ) ! f i i j i i i i 1 — -•— ! \ i ! ' I ! _ I__ 165 M a c h i n e r y f o r a n L V L P l a n t M a c h i n e r y . C o s t 1 . L o g B a r k e r 3 5 " $ 6 5 , 5 0 0 2 . H o t W a t e r H e a t i n g S y s t e m $ 3 0 , 0 0 0 3 . 8 ' L a t h e , 4 2 " s w i n g $ 1 0 9 , 0 0 0 L a t h e C h a r g e r $ 2 9 , 9 0 0 B a c k - U p R o l l $ 7 , 5 0 0 L a t h e D r i v e ( 1 5 0 H P D C ) $ 3 6 , 9 0 0 4 . V e n e e r C l i p p e r ( 8 ' ) . $ 3 1 , 0 0 0 C l i p p e r I n f e e d S y s t e m ( 4 5 ' ) $ 2 4 , 0 0 0 C l i p p e r O u t f e e d C o n v e y o r s ( 7 5 ' ) $ 9 , 5 0 0 5 . P a n e l S a w . $ 4 3 , 5 0 0 P a n e l S a w ' F e e d e r $ 1 7 , 0 0 0 6 . V e n e e r R o l l e r D r y e r 8 D e c k x 1 2 S e c t i o n s ( a p p r o x . 7 0 ' o f d r y i n g l e n g t h ) $ 1 9 0 , 0 0 0 D r y e r F e e d e r $ 3 0 , 0 0 0 ( i n c l u d e s s t o r a g e c h a i n , h y d r a u l i c h o i s t s e c t i o n ) D r y e r U n l o a d e r V e n e e r O u t f e e d A p r o n $ 2 1 , 0 0 0 M o i s t u r e D e t e c t o r 6 , 0 0 0 6 , 5 0 0 7 . 4 ' G l u e S p r e a d e r ( 5 3 " ) $ 1 7 , 9 0 0 e a c h C u r t a i n C o a t e r " $ 5 0 , 0 0 0 I n f e e d & O u t f e e d t o C u r t a i n C o a t e r $ 6 5 , 0 0 0 -8 . 4 ' x 1 6 ' 8 o p e n i n g P r e s s $ 2 5 0 , 0 0 0 9 . E d g e r ( 1 3 S a w G a n g ) $ 3 0 , 0 0 0 M a c h i n e r y f o r a n L V L P l a n t - c o n t ' d 166 1 0 . T r i m S a w 1 1 . F o r k L i f t ( 7 0 0 0 # c a p ) 1 2 . P u s h C a r t s 1 3 . F l a t D e c k T r u c k f o r l o g d e l i v e r y 1 4 . T r u c k ( M a r k e t i n g & G e n e r a l o f f i c e ) $ 9 , 0 0 0 $ 1 5 , 0 0 0 a p p r o x . $ 3 0 0 - 4 0 0 e a c h $ 8 5 , 0 0 0 e a c h $ 1 0 , 0 0 0 ' A b o v e p r i c e s r e f e r t o e q u i p m e n t p u r c h a s e c o s t s o n l y . N o e s t i m a t e i s i n c l u d e d f o r i n s t a l l a t i o n , l a b o u r , s t a r t - u p , s h i p p i n g o r e x p o r t c o s t s . W h e r e p o s s i b l e , t h e p r i c e g i v e n i s a n o v e r a g e c o s t o f a n y p a r t i c u l a r p i e c e o f m a c h i n e r y . F o r e x a m p l e , a 3 6 " r i n g b a r k e r c a n c o s t a n y w h e r e f r o m $ 4 5 , 0 0 0 u p t o $ 1 0 0 , 0 0 0 , d e p e n d i n g o n t h e s u p p l i e r a n d t h e o p t i o n s d e s i r e d . r ^ w ^ u . 3-7p 

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