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Permeability of a mountain-type Douglas fir stem containing included sapwood bands Koran, Zoltan 1961

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PERMEABILITY OF A MOUNTAIN-TYPE DOUGLAS FIR STEM CONTAINING INCLUDED SAPWOOD BANDS by ZOLTAN KORAN B.S.F. (Sbpron), The University o f B r i t i s h Columbia, 1959  A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER i n the Faculty of Forestry  We accept t h i s t h e s i s as conforming to the required standard  THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1961  In the  presenting  requirements  of  British  it  freely  agree for  that  an  advanced  for  available  I  copying  gain  shall  by or  not  of  his  p a r t i a l  degree  at  the  shall  reference  and  study.  I  extensive  may  be  allowed  The U n i v e r s i t y o f B r i t i s h Vancouver Canada.  of  copying  granted  this  without  Columbia  by  of  the  It thesis  this of  thesis my  understood  for  my w r i t t e n  make  further  Head  is  of  University  Library  representatives.  forestry  fulfilment  the  publication be  i n  that  for  purposes  or  agree  for  permission  that  Department  thesis  Columbia,  scholarly  Department  this  f i n a n c i a l  permission.  '  I.  ABSTRACT Penneability to creosote of sapwood, included sapwood, and normal heartwood of a mountain-type Douglas f i r stem was  correlated with s p e c i f i c  g r a v i t y , growth rate, percent summerwood, tracheid length, number o f l o n g i tudinal r e s i n ducts, alcohol-benzene, acetone and ether-soluble contents of the corresponding zones. ature on creosote r e t e n t i o n was  extractive  The e f f e c t of pressure and temper-  tested on creosote  retention i n true sapwood,  included sapwood (abnormal heartwood), and normal heartwood.  Test specimens  were extracted i n d i f f e r e n t solvents and ease of penetration tested by creosote  impregnation. Among the factors investigated i n the present study, s p e c i f i c  g r a v i t y , tracheid length, growth r a t e , and number o f l o n g i t u d i n a l r e s i n ducts did not have a measurable influence on creosote retention.  Percent  summei*wood d i d not vary s i g n i f i c a n t l y at the f i v e positions tested. Pressure had the greatest e f f e c t on creosote retention at 212°F. for heartwood, l e s s f o r included sapwood and l e a s t for sapwood.  The  influence of temperature on creosote retention i n Douglas f i r heartwood was  greater, at 100 p s i pressure than at atmospheric pressure.  o f alcohol-benzene and acetone-soluble was  not proven s t a t i s t i c a l l y  ship was  The e f f e c t  extractives on wood permeability  significant.  A v i s u a l hyperbolic r e l a t i o n -  obtained between ether-soluble extractives and wood permeability.  The higher the extractive content, the greater the retention.  Pre-treatment  of samples with d i f f e r e n t solvents, i n order to remove some o f the  extrac-  t i v e s , improved the permeability of heartwood and included sapwood s i g n i f i c a n t l y but caused only a s l i g h t improvement i n sapwood.  XX.  CONTENTS  Page_  INTRODUCTION.....  1  LITERATURE REVIEW  2  1.  2.  P h y s i c a l and Chemical Structure o f Douglas F i r Wood  2  (a)  Physical properties  2  (b)  Chemical structure.....  7  General  MATERIAL AND METHODS  9 12  1.  Material  12  2.  Methods  13  A.  Absorption Studies (a) Preparation o f t e s t specimens (b) Conditioning to 14 percent moisture content. (c) Sealing (d) Treatment conditions ( i ) Pressure. ( i i ) Temperature ( i i i ) Duration of treatment............... (e) Preservative..... (f) Measurement of absorption Determination of Some o f the Physical and Chemical Properties of Wood * (a) P h y s i c a l properties '. ( i ) S p e c i f i c gravity ( i i ) Percent summerwood ( i i i ) Growth rate (iv) Tracheid length (v) Longitudinal r e s i n ducts (b) Chemical properties.  13 13 13 14 15 15 15 15 18 IS  Extraction P r i o r to Impregnation (a) Preparation o f t e s t specimens (b) Extractions ( i ) Alcohol-benzene(1:2), ether, acetone, and hot water extraction ( i i ) Alcohol-benzene ( i i i ) 0.1$ Sodium hydroxide extraction (iv) Water.......... (c) Conditioning to 14$ moisture content (d) Sealing (e) Measurements o f absorption a f t e r extraction.  20 20 20  B.  C.  18 18 18 18 19 19 19 19  21 21 21 21 21 22 22  iii Page D.  Microscopic Studies....................  22  (a)  Preparation of s l i d e s . . . .  22  (b)  Microscopic observations  22  RESULTS  22  A.  Absorption Studies....  22  B.  P h y s i c a l and Chemical Properties o f the Wood (a) Physical properties (i) Specific gravity.. ( i i ) Percent summerwood. ( i i i ) Growth rate (iv) Resin ducts (v) Fibre length  23 23 23 23 23 23 24  (b) C.  '.  Chemical properties  Extraction Studies  DISCUSSION 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12.  Effect o f pressure on creosote retention Influence of temperature on creosote retention Correlation between s p e c i f i c gravity and permeability.......... Influence of percent summerwood on permeability ; E f f e c t of growth rate on creosote retention Relationship between f i b r e length and creosote r e t e n t i o n Influence of l o n g i t u d i n a l r e s i n ducts on p e n e t r a b i l i t y Correlation between extractive content and t r e a t a b i l i t y Improvement i n t r e a t a b i l i t y due to extraction E f f e c t of solvent on wood Bordered p i t a s p i r a t i o n Direction of penetration  24 24 24 24 28 33 36 36 37 37 38 40 44 45 46  SUMMARY  47  REFERENCES  50  APPENDIX  54  iv. FIGURES  Page, 1.  Diagram o f a bordered p i t  2.  A section o f an interior-type Douglas f i r timber....  13  3.  A small pressure retort  16  4.  Rate o f absorption o f creosote i n mountain-type Douglas f i r sapwood  17  The e f f e c t of d i r e c t i o n of penetration on creosote retentions i n mountain-type Douglas f i r wood at 70°F. t r e a t i n g temperature and at atmospheric pressure  27  E f f e c t o f pressure and temperature on creosote retention i n a mountain-type Douglas f i r stem  30  The influence o f pressure and temperature on creosote retent i o n i n a mountain-type Douglas f i r stem  31  Influence o f pressure and temperature on creosote retention i n mountain-type Douglas f i r heartwood and sapwood  32  Creosote retentions and some physical and chemical properties o f a mountain-type Douglas f i r stem a t f i v e positions i n the cross section  35  Correlation between creosote retention and alcohol-benzene solubles o f mountain-type Doulgas f i r heartwood  39  Relationship between creosote retention and either-soluble extractive content of mountain-type Douglas f i r heartwood  39a  5.  6. 7. 8. 9.  10. 11. 12.  Relationship between creosote retention and acetone-soluble extractive content o f mountain-type Douglas f i r heartwood  4  Al  v. TABLES Page 1.  The o v e r - a l l composition of Douglas f i r heartwood  2.  Average creosote retentions o f the f i v e zones of a mountaintype Douglas f i r stem under d i f f e r e n t conditions of treatment...  26  E f f e c t of pressure and temperature on creosote retention i n mountain-type Douglas f i r  29  Some physical and chemical properties o f a mountain-type Douglas f i r stem.  34  Average creosote retentions of mountain-type Douglas f i r heartwood, included sapwood and sapwood, following a 240-hour extract i o n i n d i f f e r e n t solvents  43  6.  Creosote absorption values of mountain-type Douglas f i r sapwood.  54  7.  Creosote retentions i n mountain-type Douglas f i r sapwood, included sapwood, and heartwood under d i f f e r e n t conditions of treatment  55  Analysis o f variance of creosote retention i n mountain-type Douglas f i r as affected by pressure, temperature, p o s i t i o n and d i r e c t i o n o f penetration •  56  S p e c i f i c gravity values of a mountain-type Douglas f i r stem  57  Percent summerwood values i n mountain-type Douglas f i r stem and analysis o f variance  58  Fibre length values f o r various sections i n a mountain-type Douglas f i r stem  59  3. 4. 5.  8.  9. 10. 11. 12. 13.  Alcohol-benzene, acetone, and ether s o l u b i l i t y o f mountain-type Douglas f i r wood Creosote retentions of mountain-type Douglas f i r heartwood, included sapwood, and sapwood following a 240-hour extraction i n d i f f e r e n t solvents  8  60  61  ACKNOWLEDGEMENTS  The author wishes to express his gratitude to Dr.  R.W.  Wellwood and Mr. R.W. Kennedy, o f the Faculty of Forestry, The University of B r i t i s h Columbia, f o r t h e i r constructive d i r e c t i o n and h e l p f u l c r i t i c i s m . Special thanks are due Mr. R. Buff, Manager of the Buff Lumber Company, Westwold, B r i t i s h Columbia f o r supplying the material used i n t h i s p r o j e c t . The author would also l i k e to g r a t e f u l l y acknowledge the help given by the Vancouver Laboratory, Forest Products Research Branch, Canada Department of Forestry, f o r the free use of their f a c i l i t i e s .  INTRODUCTION The movement o f l i q u i d s i n wood i s of great i n t e r e s t to several branches of the wood Industry. f i r e - p r o o f i n g , dimensional  I t i s p a r t i c u l a r l y so i n wood preservation,  s t a b i l i z a t i o n , pulp and paper manufacturing, and  also i n the drying, gluing, and f i n i s h i n g of wood. During the past 60 years a considerable amount o f work has been done on the evaluation o f the factors a f f e c t i n g the penetration of preserv a t i v e s , e s p e c i a l l y creosote, into Douglas f i r timber.  As a r e s u l t o f these  experiments a great improvement can be seen i n the techniques nating Douglas f i r with o i l - and water-borne preservatives.  f o r impregHowever, there  s t i l l remains a great deal of research work to be done i n t h i s f i e l d . I t i s a well known f a c t that Douglas f i r sapwood can be impregnated with preservative l i q u i d s more e a s i l y than the heartwood.  In addition,  preliminary t e s t s performed by the author t h i s year indicated that the permea b i l i t y of c e r t a i n portions of Douglas f i r heartwood i s superior to that of others.  These more permeable parts of the heartwood, interspersed among the  zones of normal heartwood, have the color of sapwood, and are i n f a c t zones of included sapwood. This recent observation of the superior permeability o f included sapwood (abnormal heartwood) over that of the normal heartwood, o f f e r s a completely new  approach to the i n v e s t i g a t i o n of some of the factors a f f e c t i n g  the penetration of creosote into Douglas f i r . The present i n v e s t i g a t i o n may The object of the f i r s t part was  be divided into three major parts.  to deteraine the pattern of absorption of  creosote at d i f f e r e n t points i n a section o f a l o g of i n t e r i o r Douglas f i r containing included sapwood bands.  Various treatments were used to i n v e s t i -  gate the e f f e c t of pressure and temperature on the penetration of creosote into t h i s material.  -2The purpose of the second part was to determine some o f the p h y s i c a l and chemical properties of the end-matched specimens used f o r the absorption studies.  The physical properties investigated were s p e c i f i c  g r a v i t y , growth r a t e , percent summerwood, number o f l o n g i t u d i n a l r e s i n ducts per unit of cross section area, and f i b r e length.  Of the chemical properties,  the quantities o f alcohol-benzene, acetone and ether solubles were determined.  This enabled a c o r r e l a t i o n to be made o f the pattern o f absorption  with the p h y s i c a l and chemical properties o f the appropriate wood specimens. In the t h i r d part o f the study, wood blocks, s i m i l a r to those used i n the f i r s t part of the study, were extracted with several organic solvents f o r a standard period of time.  Following extraction the specimens  were treated with creosote and the ease of penetration determined i n order to t e s t the hypothesis that the extractive content o f the material affected i t s penetrability. LITERATURE REVIEW 1. (a)  Physical and Chemical Structure o f Douglas F i r Wood Physical properties (7) Douglas f i r wood i s composed o f two major types o f elements,  l o n g i t u d i n a l and transverse.  T he l o n g i t u d i n a l elements consist p r i m a r i l y  o f wood tracheids and secondly o f e p i t h e l i a l parenchyma c e l l s of the r e s i n canals.  These l o n g i t u d i n a l elements constitute over 90 percent o f the  volume o f most softwoods. The tracheids are hollow c e l l u l o s i c tubes tapered and closed at both ends, and somewhat rectangular o r e l l i p t i c a l i n cross-section  (13)•  The i n d i v i d u a l tracheids are connected with each other by bordered p i t s , which are hence important f o r the movement o f l i q u i d s both i n the l i v i n g  and dead-tree.  A diagram of such a bordered p i t i s shown i n Figure 1.  Great importance i s attached to the f i n e structure of the p i t membrane of bordered p i t s since the preserving l i q u i d must pass through the permanent pores of t h i s membrane.  The p i t s are located on the r a d i a l walls of the  springwood tracheids, and are concentrated  towards the ends.  They occur  mainly i n a single v e r t i c a l row on the c e l l w a l l , but occasionally form double rows.  The p i t s i n the summerwood zone are l e s s numerous, smaller  i n s i z e and may be located on both the tangential and r a d i a l walls, depending upon the p a r t i c u l a r species. The bordered p i t has an overhanging rim, more or l e s s c i r c u l a r i n surface view, and the p i t i s divided by the c l o s i n g apparatus. closing membrane consists of the torus and the p i t membrane. c i r c u l a r i n o u t l i n e , and i s of sandwich construction.  The  The torus i s  The t h i n middle  lamella i s held between, or holds together, the two primary wall thickenings. The p i t membrane consists of a network of c e l l u l o s i c filaments radiating from the torus t o the margin o f the p i t c a v i t y .  The filaments appear to  a r i s e from the two faces of the torus and to be made of m i c r o f i b r i l s joined into coarser strands (15, 17, 25, 26, 33, 34, 36).  Springwood c e l l s are  characterized by r e l a t i v e l y t h i n walls, with rather long overhanging p i t borders, whereas the summerwood c e l l s have t h i c k walls, small p i t c a v i t i e s and thick, short t o r i .  Stamm (48) measured the size o f the permanent pores  i n the p i t membrane by physical methods, and reported an average pore diameter of 28.2 m i l l i m i c r o n s . Buckman and associates (10) found that the e f f e c t i v e diameters of the permanent pores i n the p i t membrane vary with the moisture content of the wood.  Below the f i b r e - s a t u r a t i o n point the e f f e c t i v e pore diameter  Figi.  Diagram  of  a  bordered  pit  (15,25).  "S  /  7 \  \  /  A. Bordered radial  pit  as  seen  on  o  section.  B. Bordered  pit -pair as seen  tangential  or  cross  on either  section  a. A p e r t u r e .  b. Torus. C.  Annulus.  C. B o r d e r e d D. Front  view  membrane .  p i t In a s p i r a t e d of o t o r u s  condition.  and pit  decreases with increasing moisture content. Smith (46)  Recent r e s u l t s obtained by-  indicated that the average size o f the openings  controlling  flow through certain softwoods i s equivalent to a diameter o f about 2-3 Marts(36) reported an average diameter o f 23 microns f o r the  microns. border, U  microns f o r the torus and 7 microns f o r the aperture o f the  Douglas f i r bordered p i t s . In Douglas f i r , l o n g i t u d i n a l parenchyma c e l l s are quite sparse and scattered throughout the growth r i n g s .  Their function i n the l i v i n g  tree i s to store reserve food and extractives.  The parenchyma c e l l s can be  i d e n t i f i e d by t h e i r f l a t , blunt ends and the presence of simple p i t s i n the c e l l wall.  Overhanging rims, p i t c a v i t i e s , and t o r i are lacking i n these  simple p i t s .  Thus simple p i t p a i r s are merely round holes i n the contig-  uous c e l l walls, with a d i v i d i n g membrane between. E p i t h e l i a l parenchyma c e l l s l i n i n g the v e r t i c a l r e s i n ducts are found i n Douglas f i r .  The r e s i n ducts are postcambial i n formation and  occur only as i n t e r c e l l u l a r spaces i n the wood. The transverse or r a d i a l wood elements are the wood ray c e l l s . Wood rays are o f two different types, uniseriate and fusiform. The u n i seriate rays are generally one c e l l i n width and from one to many c e l l s i n height.  In Douglas f i r , ray tracheids form the marginal c e l l s of the ray,  and the other c e l l s are parenchymatous.  The fusiform ray consists o f the  same elements as the uniseriate with the addition of e p i t h e l i a l c e l l s that surround a transverse r e s i n duct.  As a r e s u l t , these rays are several c e l l s  wide i n the middle and taper t o one c e l l i n width at the margins.  The main  functions o f wood rays are food storage and translocation from the inner bark to the l i v i n g c e l l s i n the tree stem.  -6-  The stem i s b u i l t up o f growth rings or annual rings, normally one being formed every year.  Each growth ring contains two d i s t i n c t zones,  namely, springwood and summerviood.  These zones are the result of rapid  growth at the beginning of each growing season.  During the period of fast  growth, when conduction of water and raw materials to the crown i s important, thin-walled tracheids with large lumens are formed.  As growth slows down i n  the l a t t e r part of the growing season, thick-walled tracheids are formed. The abrupt t r a n s i t i o n between the thick-walled summerwood tracheids of one year's growth, and the larger thin-walled springwood tracheids of the next year, makes the annual ring d i s t i n c t i n appearance. A Douglas f i r stem can be divided into two major zones, namely, the sapwood and heartwood.  A l l c e l l s i n the heartwood portion o f the stem  are dead and t h e i r function i s mechanical support.  In the sapwood the  tracheids die shortly a f t e r they are formed, but s t i l l function as conducting elements.  As new  c e l l s are continually formed by the cambium, and added to  the sapwood, a proportionate number of the o l d sapwood c e l l s are converted to heartwood.  These c e l l s , as they become part of the heartwood, possess a  higher resistance to the entry of fungi and preserving l i q u i d s than the sapwood c e l l s .  In addition, they l o s e a l l t h e i r functions except mechanical  support. In the case o f the so-called included sapwood, the conversion sapwood to heartwood appears to be incomplete.  of  This assumption i s confirmed  by the low extractive content, and by the lack of coloring matter i n the included sapwood zones. Certain changes take place i n wood during the conversion of sapwood to heartwood.  Numerous p i t s become aspirated.  A bordered p i t becomes  aspirated when the torus moves to one s i d e of the p i t c a v i t y and closes the  p i t aperture.  In addition, resins and other extractives present i n the  sapwood usually become hard and remain deposited within the r e s i n ducts and c e l l lumina i n the heartwood.  However, no basic change takes place i n  the structure of the wood. (b)  Chemical structure Chemically, the f u l l y matured c e l l w a l l consists of varying amounts  o f c e l l u l o s e , l i g n i n and n o n - c e l l u l o s i c polysaccharides. skeleton around which the other substances are deposited.  Cellulose i s the This substance i s  considered to consist of long molecular chains of glucose residues.  The  long chains of c e l l u l o s e molecules i n the c e l l walls are p a r a l l e l over at l e a s t part of t h e i r length.  In these zones of p a r a l l e l i s m the units o f  glucose anhydride are bonded lengthwise as well as crosswise.  The p a r a l l e l  r e p l i c a t i o n of the c e l l u l o s e chains builds up the whole c r y s t a l l i n e structure of cellulose. Between the c r y s t a l l i t e s i n the amorphous regions, the c e l l u l o s e chains are only p a r t i a l l y p a r a l l e l .  They are somewhat disorganized and  thus cross valences are lacking or g r e a t l y reduced.  The advent o f electron  microscopy and i t s a p p l i c a t i o n to c e l l wall studies revealed the presence of well defined units c a l l e d m i c r o f i b r i l s , which i n d i f f e r e n t c e l l u l o s i c materials average approximately thickness (15)•  o  200 A i n breadth and vary from 25 - 100  These m i c r o f i b r i l s are of i n d e f i n i t e length and are appar-  ently somewhat rectangular i n cross-section. Frey-Wyssling, Dadswell (16),  o  A in  as stated i n  further suggested that a m i c r o f i b r i l , with a cross-section o f  o 100 x 200 A, consists o f four so-called elementary f i b r i l s each containing a c r y s t a l l i n e core, separated from each other by regions of lower order of crystallinity.  Most o f the n o n - c e l l u l o s i c polysaccharides, and l i g n i n , are  packed between the m i c r o f i b r i l s .  -sExtraneous components can be subdivided  into two groups.  The  f i r s t group, c a l l e d "extractives", i s composed of chemicals which can be removed e a s i l y by neutral solvents.  Among these extractives are substances  such as r e s i n acids, colouring matter, and waxes.  The second group consists  o f miscellaneous components such as starch grains, s i l i c a , and oxalate c r y s t a l s .  calcium  These are substances which cannot e a s i l y be removed by  solvents, but nevertheless  are quite d i s t i n c t from the c e l l walls.  Extractives are generally found i n the c e l l c a v i t i e s . They may also be present i n very f i n e c a p i l l a r i e s o f the c e l l wall, thereby making t h e i r complete removal  impossible.  The o v e r - a l l percentage composition of Douglas f i r heartwood deterniined by Graham and Kurth (23).  was  The sample was taken from a wide-  ringed, f r e s h l y - c u t , second-growth Douglas f i r .  The extractive contents  were based on the oven-dry weights of the unextracted wood and were determined successively f o r ether, alcohol, and hot-water-soluble extractive. Other components of wood were based on the weights of oven-dry extracted wood.  Their r e s u l t s are shown i n Table 1.  TABLE 1.  The o v e r - a l l composition of Douglas f i r heartwood (23).  Extractives and constituents Moisture Ether s o l u b i l i t y Alcohol s o l u b i l i t y Hot-water-solubility  Percentage 9.10 1.32 5.46 2.82  Total extractives: Ash L i g n i n ( t o t a l sample) (40-60 mesh sample) Holocellulose Pentosan Methoxyl  9.60  0.175 30.15 29.35 71.40 10.11 4.75  -92.  General In the past a great deal of experimental work has been done on  the penetration of preservative liquids into wood. Most of these studies included the investigation of the pathways through which preservatives can enter wood. Tiemann (51), in 1909, explained the permeability of wood on the basis that seasoning or drying causes the formation of narrow, spiral, microscopic tion.  checks in the tracheid walls, thus producing means of penetra-  In addition, he stated that the larger these openings are, the more  permeable the wood is to preservatives. Weiss ( 5 2 ) confirmed the above theory, and explained the superior permeability of summerwood over springwood by the fact that the thickwalled summerwood cells check more than the thin-walled springwood cells, thus providing larger channels for liquid movement. On the other hand, Gerry ( 2 1 ) attributed no significance to these microscopic splits, i n the penetration of creosote into larch. Bailey ( 2 ) was the f i r s t investigator to realize the importance of bordered pit membranes in the impregnation of coniferous woods by liquids. The positions of the t o r i in the bordered pits was studied by Griffin ( 2 5 ) , Shefound that the majority of the t o r i were in the aspirated condition in those wood specimens which showed poor penetration of preservatives.  However,  in the specimens that obtained good treatment, most of the t o r i were in central position. She reported that the aspiration was caused by drying. The relation of the aspirated bordered pits to the unaspirated ones, as a percentage, was determined by Stamm ( 4 7 ) .  He found that this  ratio was 4 0 percent for coast-type Douglas f i r and only 1 4 . 6 per cent for mountain-type Douglas f i r .  -10P h i l l i p s (38) the aspiration was cell.  substantiated G r i f f i n ' s findings and believed that  due t o the l o s s of the l a s t trace o f free water i n the  He found that a l l the springwood p i t s became aspirated upon drying,  but a portion of the summerwood p i t s remained unaspirated.  This  was  explained by the difference i n r i g i d i t y of the summerwood and springwood p i t membranes, and by the s i z e o f the p i t apertures. In 1936, No r e l a t i o n s h i p was  Stone (49)  investigated the bordered p i t s of Douglas f i r .  found between the degree of a s p i r a t i o n of the p i t s and  the p e n e t r a b i l i t y o f l i q u i d s into the wood.  The majority of the t o r i  appeared to be i n a completely aspirated p o s i t i o n when he observed 2-micront h i c k Douglas f i r sections under a compound binocular microscope at 440 magnification.  X  However, by means of photomicrographs taken i n u l t r a v i o l e t  and polarized l i g h t , the same t o r i were observed as not being f u l l y aspirated at magnifications up to 9000 diameters.  Stone explained that the t o r i were  not completely aspirated because t h e i r surfaces were not smooth, but were quite i r r e g u l a r i n nature.  This was  confirmed by other investigators.  He  also stated that l i q u i d would have l i t t l e d i f f i c u l t y i n passing through the space between the over-hanging lamella and the edge of the torus. These f i n d i n g s were confirmed by Erickson, Schmitz and Gortner  (18).  They concluded that e i t h e r p i t a s p i r a t i o n does not occur as extensively as reported i n the l i t e r a t u r e , or else i t does not greatly influence permeability. In his recent study with water-borne preservatives, Preston  (40)  concluded that the major portion passes through the transient c e l l - w a l l c a p i l l a r i e s , and only a small portion goes through the bordered p i t s .  He  supports t h i s statement by the f a c t that the number of transient c e l l - w a l l  -11-  c a p i l l a r i e s f a r exceeds the number of permanent pores i n the p i t membranes. According to Stamm ( 4 8 ) , the f r a c t i o n a l cross-sectional area of the transient c e l l wall c a p i l l a r i e s i s of the order of 0 . 1 , whereas that of the permanent pores of the p i t membrane i s of the order of 0 . 0 0 4 .  Taking the above  factors into consideration, he a t t r i b u t e s a minimum importance to the a s p i r ation o f bordered p i t s i n determining the permeability of wood to water or similar l i q u i d s . Proctor and Wagg ( 4 1 ) found that the number of r e s i n ducts per u n i t area i n the coast-type Douglas f i r was seven times that o f the mountaintype Douglas f i r .  They also found more longitudinal r e s i n ducts i n the  wider growth rings and concluded that there may be a r e l a t i o n s h i p between t r e a t a b i l i t y and the number of r e s i n ducts.  F l e i s h e r ( 1 9 ) related permeabilf.  i t y o f Douglas f i r to lumen cross-sectional area and f i b r e length.  He found  the lumen cross-sectional area to be l a r g e r i n permeable Douglas f i r than i n the impermeable type. Summerwood i s generally more permeable than springwood f i r heartwood.  i n Douglas  E a r l i e r investigators ( 2 5 , 26, 3 0 ) explained t h i s by the  displacement of t o r i to a greater degree i n springwood than i n summerwood. The following reasons may account f o r the difference i n permeability o f springwood and summerwood: (1)  The r e s i n ducts were found to be l o c a l i z e d mainly i n the summerwood zones o f the growth r i n g s .  (2)  The bordered p i t s i n the summerwood tracheids are smaller and fewer i n number than i n the springwood f i b r e s , but they often occur as p i t canals with the torus i n the dividing membrane apparently lacking ( 7 ) .  -12(3)  The summerwood lumlna are also smaller than springwood lumina, and c a p i l l a r y action o f the preservative may account for greater penetration.  (4)  Weiss (52) suggested that the dense, thick-walled summerwood tracheids check more r e a d i l y than the l i g h t , thin-walled springwood c e l l s , thus accounting  f o r the greater penetration o f creosote  i n summerwood. I t was suggested by Buro and Buro (12) that the p o s i t i o n of the torus i s not the only f a c t o r responsible f o r p e n e t r a b i l i t y . They a t t r i b u t e some s i g n i f i c a n c e to the substances deposited i n the c e l l wall.  Miller (37),  based on his studies of the permeability i n Douglas f i r , arrived at a s i m i l a r conclusion.  He states that permeability may be associated with both the  minute structure and the chemistry o f wood.  MATERIAL AND METHODS 1.  Material A four-foot section o f a green Douglas f i r (Pseudotsuga menziesii  (Mirb.) Franco) l o g , 2 0 inches i n diameter, and about 340 years o l d , was used for this investigation.  The l o g , as viewed i n the cross section,displayed  a "target r i n g " pattern o f heartwood and included sapwood zones (Figure 2 ) . The material was free from surface defects and had a slope o f grain l e s s than one i n twenty.  The tree was cut approximately 12 miles southeast o f Kamloops,  at an elevation o f 3500 f e e t , and therefore represents the mountain-type (or interior-type) o f Douglas f i r .  -13-  Figure 2.  2.  Methods A.  (a)  A section of an interior-type Douglas f i r timber.  Absorption Studies  Preparation o f test specimens.  Since the Douglas f i r l o g section  contained two included sapwood bands, one set o f three side-matched specimens of £" x  x 36" w a s prepared from the t r u e sapwood, one set from each of  the two included sapwood zones and one each from two normal heartwood zones (Figure 2 ) .  The side-matched specimens were c a r e f u l l y prepared i n such a  way that each would contain the same annual rings.  Eighty £-inch cubes  were then prepared from each of the f i v e sets and l a b e l l e d simultaneously, (b)  Conditioning to 14 percent moisture content. Following preparation,  the t e s t specimens were placed i n an e l e c t r i c a l l y - c o n t r o l l e d conditioning  -14chamber.  A constant r e l a t i v e humidity o f 74 percent was maintained i n the  conditioning chamber, at 74°F. dry-bulb and 68°F. wet-bulb  temperature.  Test samples were removed from the chamber p e r i o d i c a l l y , and t h e i r moisture contents determined.  Six weeks was adequate to obtain a uniform equilibrium  moisture content o f 14 percent i n a l l t e s t specimens. (c)  Sealing.  To measure the amount o f creosote absorbed i n r a d i a l , tangen-  t i a l , and longitudinal d i r e c t i o n s , the appropriate face o f the cubes was l e f t unsealed and the remaining f i v e faces sealed.  Five sides o f the test  specimens (rather than four) were sealed, i n order to provide a more r e l i a b l e measure o f longitudinal penetration i n the r e l a t i v e l y short specimens.  The  control specimens were sealed on three neighbouring sides and l e f t open on the opposite sides.  I t was necessary to sand the blocks before sealing i n order  to prevent the formation of channels which would permit the movement of l i q u i d under the sealer.  The  t e s t specimens were numbered with a red wax  p e n c i l before the application of the sealer, f o r easy i d e n t i f i c a t i o n after treatment. The sealer was made by dissolving a p l a s t i c material ( i n t h i s case a p l a s t i c ruler) i n acetone. by the addition of solvent. paint brush.  The v i s c o s i t y o f the solution was regulated The sealer was spread onto the blocks with  Several coats were applied i n order to provide a continuous  f i l m over the end-grain surfaces of the t e s t specimens. sealer applied was a s o l u t i o n o f low v i s c o s i t y .  The f i r s t coat of  T he main reason was to  provide adequate penetration for the establishment of a good mechanical bond between the sealer and the wood.  The second reason was to a i d i n the  escape o f a i r from the surface of the wood, which would otherwise appear under the sealer i n the form of a i r bubbles. higher v i s c o s i t y solution.  The following coats were of a  The evaporation of acetone from each coating  took approximately f i v e minutes.  -15(d)  Treatment Conditions (i)  Pressure Two pressures were employed to t r e a t the test specimens - 100 p s i  and atmospheric pressure. The application of pressures greater than 100 p s i was not considered because the combined e f f e c t of high pressure and temperature might have caused collapse i n the wood specimens.  The pressure t r e a t -  ment was done at the Vancouver Laboratory, Forest Products Research Branch, Canada Department of Forestry, using the small pressure r e t o r t shown i n Figure 3. (ii)  Temperature Half the blocks were treated at room temperature (70°F.) and the  other h a l f at the b o i l i n g point of water (212°F.).  The 212°F. temperature  o f the preservative was maintained by keeping the treating apparatus i n b o i l i n g water f o r the e n t i r e t r e a t i n g p e r i o d . (iii)  Duration of treatment An 8-hour time period was applied i n a l l treatments.  This  duration was determined from a preliminary treatment performed at room temperature and atmospheric pressure. A sapwood control specimen was attached to the arm o f a scale i n such a way that the specimen could be immersed i n creosote.  Immediately a f t e r  the immersion, the submerged weight o f the specimen and attachment was determined to the nearest centigram.  Weight readings were then taken at 15-fflinute  i n t e r v a l s for the f i r s t 2 hours and hourly f o r the next 8 hours.  Since the  volume o f the specimen presumably remained constant, the increase i n weight was equal to the amount of creosote absorbed by the wood.  Absorption values,  reported i n Table 6, were p l o t t e d against time and the 8-hour t r e a t i n g period determined from the graph on Figure 4.  -16-  Figure  3.  A small pressure r e t o r t .  Fig.  4  Rate in  of  absorption  mountain - type  of  creosote  Douglas  fir  sapwood.(S)  ->3 I  Time  7  in  hou rs  -1$-  (e)  Preservative Coal-tar creosote was used i n t h i s i n v e s t i g a t i o n .  Creosote was  taken from the same source throughout the experiment i n order t o eliminate errors introduced due to v i s c o s i t y and s p e c i f i c gravity d i f f e r e n c e s . (f)  Measurement of absorption Following the sealing process the t e s t specimens were weighed and  separated into four treatment groups.  The: f i r s t group was treated at atmos-  pheric pressure and room temperature ( 7 0 ° F . ) , the second a t atmospheric pressure and 212°F temperature, the t h i r d at 1 0 0 p s i pressure and 70°F., and f i n a l l y the fourth group at 1 0 0 p s i pressure and 212°F.  The excess  creosote was removed from the specimens and t h e i r weight redetermined. The amounts of creosote., retained i n the wood specimens i n grams, were calculated and recorded (See Table 7 ) .  B. (a)  Determination of Some o f the Physical and Chemical Properties o f Wood  Physical properties (i)  Specific gravity.  Four t e s t specimens were taken from each o f the  f i v e groups o f specimens and t h e i r s p e c i f i c g r a v i t i e s determined using the water displacement method ( 7 ) . ( i i ) Percent summerwood. Five end-matched wood blocks were taken from the t e s t specimens used i n the absorption studies.  Each block was aspirated f o r  approximately 1 0 hours before 30-micron transverse sections were cut on a s l i d i n g microtome.  S l i d e s were then prepared from the sections.  Mork's  d e f i n i t i o n , which states that summerwood s t a r t s where twice the double r a d i a l t r a c h e i d wall thickness equals the r a d i a l diameter of the lumen, was considered the point of i n i t i a t i o n o f summerwood ( 4 5 ) .  -19(iii)  Growth rate.  The s l i d e s prepared for percent summerwood deter-  minations were used to measure the number o f rings per r a d i a l inch. (iv)  Tracheid length. Match-stick size pieces were s p l i t from each o f  the f i v e samples i n such a way that each included the f u l l range o f growth rings.  The samples of each group were boiled i n separate t e s t tubes f o r a  period o f four hours i n a solution o f equal volumes of g l a c i a l acetic acid and hydrogen peroxide. Following the maceration, the pulp was washed overnight i n running water. slow alcohol s e r i e s .  The f i b r e s were stained, then dehydrated, using a  Two s l i d e s from each of the f i v e groups were prepared  f o r tracheid length determination. and 20 from each group.  Ten tracheids were measured on each s l i d e  An inverted microscope was used i n t h i s experiment.  Both springwood and summerwood tracheids were randomly measured, no attempt being made to separate the two types. (v)  Longitudinal r e s i n ducts.  The t o t a l number of l o n g i t u d i n a l r e s i n  ducts was determined on each s l i d e prepared for percent summerwood determination.  Th'e^ area of each section was then measured and the number of r e s i n  ducts per square inch computed. (b)  Chemical properties In the course of t h i s part o f the investigation, the same type of  end-matched specimens were used as i n the previous studies.  Sample "S" was  taken from the true sapwood, samples "A" and "D" from the t r u e heartwood, and samples "B" and "C" from the included sapwood (Figure 2). Alcohol-benzene, acetone, and ether-soluble extractive contents of the f i v e sets o f samples were determined i n accordance with Tappi Standards T6-m tively  59-and.-T5-m 59, respec-  (1). The extractive content o f wood was reported as percentage by weight  o f the soluble matter i n the moisture-free wood.  Two determinations were  performed i n each case, and the results recorded as the averages of the two  -20values. C. (a)  Extraction P r i o r to Impregnation  Preparation of t e s t specimens Samples were taken from the sapwood (S), included sapwood ( C ) ,  and true heartwood (D) zones (Figure 2 ) .  End-matched specimens, ff-inch  i n cross-section and \ inch along the grain, were prepared from each zone and numbered simultaneously.  Each sample was then sanded on a b e l t sander  and inspected f o r natural defects. (See Table (b)  A t o t a l o f 58 specimens was prepared  13).  Extractions One-third of the test specimens from each zone (eight) were  treated with various organic solvents, using the Soxhlet extraction method; another t h i r d by the hot extraction method^ while the remaining t h i r d controls were not treated. For the Soxhlet-type  extraction, the wood blocks were placed i n  the Soxhlet apparatus, and the solvent i n the f l a s k b o i l e d b r i s k l y i n order to ensure s i x to eight siphonings per hour. In the hot extraction method, the wood blocks were b o i l e d i n various solvents, which were changed p e r i o d i c a l l y to maintain t h e i r effectiveness. The detailed set-up of the extraction study i s presented i n Table 13. A standard extraction period o f 240 hours, or 10 days, was used f o r both types of extraction.  The 240-hour period was chosen i n order to ensure that  a s u f f i c i e n t length o f time was allowed for the solvent to reach the middle portions o f the r e l a t i v e l y impermeable heartwood.  The dimension o f the t e s t  specimens along the g r a i n was reduced from ^ inch to •§• inch, i n order to improve the l o n g i t u d i n a l penetration o f the solvent.  These solvents were  alcohol-benzene (1:2), acetone, ether, sodium hydroxide {0.1%) and water. The e f f e c t of the extraction period was not undertaken i n t h i s study. Two specimens from the included sapwood (C) and two from the heartwood (D) were treated by the hot extraction method and two from each by the Soxhlet-type extraction.  Thus, the number o f wood specimens extracted  by each procedure described below amounted to eight (See Table 13).  Only  the hot water type of extraction was employed i n the treatment of sapwood. A t o t a l o f three sapwood specimens received extraction treatment. (i)  Alcohol-benzene (1:2), ether, acetone, and hot water extraction.  The extraction procedure was started with alcohol-benzene, followed by ether, The period of extraction i n each solvent was 60 hours,  acetone and water.  giving a t o t a l of 240 hours. (ii)  Alcohol-benzene. The t e s t specimens were extracted i n alcohol-  benzene (1:2)  f o r 220 hours, i n alcohol f o r 10 hours and f i n a l l y boiled i n  water f o r another 10-hour period.  The purpose of the 10-hour extraction i n  ethyl alcohol was to remove the benzene from the wood, and the water extraction, to replace the alcohol with water, (iii)  0.1%  Sodium hydroxide extraction.  This solvent was used to remove  or change some of the carbohydrates and l i g n i n i n the wood i n order to improve The specimens were extracted i n the solvent f o r 230 hours,  i t s permeability.  and i n water f o r an additional 10-hour period.  The purpose of water extraction  was to remove the r e s i d u a l sodium hydroxide from the wood. (iv)  The t o t a l extraction time i n water was 240 hours, or 10  Water.  complete days.  (c)  Conditioning  to 11$ moisture content  Following specimens  extraction, both the extracted and unextracted t e s t  were placed i n an e l e c t r i c a l l y - o p e r a t e d conditioning chamber.  -22This chamber was set at 74°F. dry-bulb and at 68°F. wet-bulb which provided a 74 percent r e l a t i v e humidity.  temperature,  This i n t u r n brought about  14 percent equilibrium moisture content i n the wood. (d)  Sealing Following conditioning, the end grains o f the t e s t specimens were  sealed with p l a s t i c sealer i n the manner previously described. (e)  Measurements o f absorption a f t e r extraction Both the extracted and unextracted t e s t specimens were weighed.  They were then submerged i n creosote at room temperature and atmospheric pressure, f o r an eight-hour period.  A f t e r t h i s treatment the excess creosote  was removed from the surface o f the blocks and t h e i r weights  determined.  Retention values were then calculated and recorded (see Table 13). D. (a)  Microscopic Studies  Preparation of s l i d e s Twenty-micron thick tangential sections were cut on a s l i d i n g  microtome from each o f the f i v e zones.  The sections were stained with analine  safranin s t a i n , taken through the alcohol series, cleared i n xylene and mounted i n Canada balsam. (b)  Microscopic observations A monocular microscope was employed to study the degree of a s p i r -  ation i n the 20-micron tangential sections. Approximately  600 X magnification  was used i n t h i s study. RESULTS A.  Absorption Studies Creosote retention values of the specimens are included i n Table 7.  The average values are presented i n Table 2.  The e f f e c t o f d i r e c t i o n o f  -23penetration on retention values for one set of teat ..conditions i s shown in Figure 5.  The influence of pressure and temperature on creotote retention  in samples tested i s given i n Table 3, and in Figures 6, 7, and 8. An analysis of variance for a l l the retention data i s given in Table 8.  Standard methods of analysis, as outlined by Cochran and Cox  (14),  were used to determine the significance of each factor in this study. B,  Physical and Chemical Properties of the Wood  (a) Physical properties (i)  Specific gravity.  The specific gravities of the sapwood, included  sapwood, and the heartwood zones are presented in Tables 4 and 9, and in Figure 9D.  Sapwood had the lowest specific gravity of the five zones tested,  whereas the specific gravity of heartwood was f a i r l y constant. No major difference was found between the specific gravities of heartwood and included sapwood zones. (ii) 4 and 10,  Percent summerwood. Percent summerwood values are shown in Tables and i n Figure 9C.  The average value remained f a i r l y constant through  the five zones• . Results varied from 22 to 26 percent.  The accuracy of the  method used to determine percent summerwood was approximately + 3 percent. The apparent relationship between permeability and percent summerwood was not accepted as being significant. (iii)  Growth rate.  the five zones.  Table 4 contains the average growth rate values of  It can be observed from Table 4 and Figure 9B that the growth  rate decreased from pith to bark. (iv)  Resin ducts.  The number of longitudinal resin ducts per unit area  in each zone i s recorded in Table 4 and in Figure 9G. could be observed in the cross section.  No definite pattern  -24-  (v)  Fibre length.  Tables 4 and 1 1 ,  The tracheid length values are presented i n  and i n Figure 9B.  to bark at a f a i r l y steady r a t e .  Tracheid length increased from p i t h A s l i g h t drop could be observed i n the  "D" heartwood zone near the bark. (b)  Chemical properties Alcohol-benzene  (1:2),  acetone, and ether-soluble extractives  are given i n Tables 4 and 1 2 and Figure 9F.  Correlation between the extrac-  t i v e contents and creosote retentions are presented i n Figures 1 0 , 1 1 , 12.  and  Each o f the f i v e wood samples contained a greater amount of a l c o h o l -  benzene-soluble extractives than either acetone or ether solubles. three  In a l l  cases, more extractives were removed from the D heartwood zone than  any other zone.  C;.  Extraction Studies Creosote retentions of the extracted and unextracted specimens,  following an eight-hour treatment at room temperature are presented i n Table 1 3 .  and atmospheric pressure,  Average values calculated from Table 13 are entered  i n Table 5 . The r a t i o s between the retention values o f extracted and unextracted specimens f o r sapwood, included sapwood, and heartwood were 1 . 2 , respectively. with water.  6 . 5 , and  Greatest improvement i n p e n e t r a b i l i t y resulted from extraction Permeability increase was s l i g h t l y l e s s with 0 . 1 percent sodium  hydroxide, least with extraction i n alcohol-benzene alone. DISCUSSION 1.  8.1  E f f e c t of pressure on creosote r e t e n t i o n At a temperature  retention o f 1 . 1 1  o f 2L2°F. and pressure of 1 0 0 p s i , an  grams was obtained f o r heartwood (D) (Table 2 ) .  average At the  -25-  same temperature, grams.  but at atmospheric pressure, the retention was only  Consequently,  the specimens treated at 100 p s i pressure  553 percent more creosote than those at atmospheric pressure.  0.17  absorbed Similar  c a l c u l a t i o n s were performed f o r the other zones and the r e s u l t s , i n percentages, entered i n Table 3.  An increase i n retention of 208 percent  obtained i n included sapwood (C) and 115 percent i n sapwood.  was  From the  above data, and from Figures 6,7 and 8, i t may be observed that the e f f e c t o f pressure on creosote retention i s greatest f o r heartwood (D), l e s s f o r included sapwood (B and C), and l e a s t f o r sapwood. The influence of pressure at 70°F. on creosote retention i s somewhat d i f f e r e n t than a t 212°F.  Only 150 percent increase i n retention was  obtained f o r heartwood (D), 78 percent f o r included sapwood (C) and percent for sapwood.  216  This would indicate that the influence of pressure  on creosote absorption i n heartwood i s greater a t higher temperatures at lower ones.  The opposite holds f o r sapwood.  e f f e c t on r e t e n t i o n at lower temperatures  than  Pressure has a greater  than at higher ones.  the application o f high (treating) pressures and temperatures more advantageous f o r heartwood than for sapwood.  Consequently, appears to be  In sapwood the influence  o f pressure on retention i s f a r greater than that of the temperature.  Hence  i n the treatment of sapwood, the treating pressure i s the dominant factor, with l i t t l e s i g n i f i c a n c e attached to the temperature.  In the case of heart-  wood, however, both the treating pressure and temperature are of major importance. When t r e a t i n g sapwood under high pressure, a r i s e i n temperature does not seem to be economically j u s t i f i e d .  In p r a c t i c e , however, the  narrow sapwood band i s r a r e l y , i f ever, treated without the heartwood. the other hand, often the wood preserving industry i s only interested i n impregnating the sapwood.  On  -26TABLE 2. Average creosote retentions of the five zones of a mountain-type Douglas f i r stem under different conditions of treatment. Position in the Crosssection  Pressure  True Sapwood  Radial Tangential Longitudinal A l l (control)  0.49 0.31 1.63 2.17  1.50 0.80 2.04  3.36  2.65  2.12 4.15 4.15 4.09  A v e r a g e  1.15  1.75  3.63  3.77  Radial Tangential Longitudinal A l l (control)  0.05 0.03 0.21 0.28  0.08 0.07  1.02 0.09  0.28  0.10 0.08 0.55 0.68  1.23  0.57 0.62  D  A v e r a g e  0.14  0.17  0.35  1.11  0.43  Included Sapwood  Radial Tangential Longitudinal A l l (control)  0.09 0.05 0.59 0.76  0.15 0.07 0.95 1.29  0.22 0.15 1.28 0.98  1.65 1.30 2.55 2.14  0.53 0.39 1.34  A v e r a g e  0.37  0.62  0.66  1.91  0.89  Radial Tangential Longitudinal A l l (control)  0.06  0.21  0.61  0.17 0.17 0.96 1.02  1.03  1.22 1.39 2.00 2.21  0.45 1.10 1.22  A v e r a g e  0.32  0.58  0.58  1.71  0.80  True Heartwood (inner)  Radial Tangential Longitudinal A l l (control)  0.05 0.04 0.28 0.31  0.05 0.07 0.36 0.50  0.12 0.09 0.61 0.75  0.92 1.27  1.64 1.68  0.29 0.37 0.72 0.81  A  A v e r a g e  0.17  0.25  0.39  1.38  0.55  0.43  0.67  1.12  1.98  1.05  S  True Heartwood (outer)  C  Included Sapwood B  AVERAGE:  Temperature  Atmospheric 70°F.  Direction of Penetration  212°F.  100  70°F.  psi 212°F.  Averages  (RetentiorI - grams)  0.07  0.52  0.24  0.16  0.93  3.90  3.82 4.00  1.29  1.87 2.29 2.91 3.23 2.58 0.31 0.23  1.29  0.42  The effect of direction of penetration on creosote retentions in mountain-type Douglas fir wood at 70°F. treating temperature and at atmospheric pressure. LEGEND; Radial. Tangential. In  all d i r e c t i o n s .  Longitudinal . f~|  /  f  \  17777  Heartwood D  MM  Included  sapwood  till'////  Included sapwood  C Position  B in t h e c r o s s  Average.  Heartwood A  section.  -28Sutherland (50) a t t r i b u t e s the improved absorption at high pressures to an enlargement o f the pores i n the p i t membrane. 2.  Influence o f temperature on creosote retention An average retention of 1 . 3 8 grams was obtained f o r heartwood (A)  at 1 0 0 p s i pressure and 2 1 2 ° F. (Table 2 ) .  Under the same pressure, but  at 70°F., the average retention was only 0 . 3 9 grams.  Thus a temperature  change of 142°F. resulted i n a retention increase o f 2 5 4 percent i n heart(B) wood, 195 percent i n included sapwood/ and only 4 percent i n sapwood (Table 3 ) .  This indicates that temperature had the greatest influence  on  heartwood, l e s s on included sapwood, and l e a s t on sapwood. The above order i s d i f f e r e n t at atmospheric  pressure.  Temper-  ature appears to have very l i t t l e influence on creosote retention of heartwood.  I t may be concluded, therefore, t h t the a p p l i c a t i o n of high a  temperature, without elevated pressure, does not have a s i g n i f i c a n t influence on creosote r e t e n t i o n . In other words, i n t r e a t i n g heartwood, the a p p l i c a t i o n o f both high pressure and temperature i s e s s e n t i a l . In sapwood, approximately the same retentions were obtained at 70°F. and atmospheric pressure as i n heartwood at 212°F. and 1 0 0 p s i pressure.  This c l e a r l y demonstrates the superior permeability of sapwood  over heartwood. The influence of temperature on creosote retention i n Douglas f i r heartwood i s greater at 1 0 0 p s i pressure than at atmospheric The reverse i s true of sapwood.  pressure.  Here temperature has a greater influence  on retention at atmospheric pressure than at 1 0 0 p s i pressure (Figure 8 ) . The e f f e c t of temperature on the absorption o f creosote can be explained by a change i n v i s c o s i t y of creosote with a change i n temperature. Creosote has higher v i s c o s i t y at 70°F., but becomes increasingly thinner and  -29-  TABLE 3 .  E f f e c t of pressure and temperature mountain-type Douglas f i r .  on creosote retention i n  Increase i n Creosote Retention - Percent Kind o f Wood  Pressure Increase from Atmospheric to 1 0 0 p s i at: 70°F..  212°F.  Sapwood (S)  216*  Heartwood (D)  Temperature Increase from 70°F. to 212°F. at: Atmospheric Pressure  100 p s i  115  52  4  150  553  21  217  Included Sapwood (C)  78  208  68  189  Included Sapwood (B)  81  195  81  195  Heartwood (A)  129  452  47  254  AVERAGE:  131  305  54  172  *Increase i n retention = 1 0 0  R70°F., 1 5 p s i  L = 1 0 0 3.6? - i ~ = 216%  R 7 0 P., 1 0 0 p s i average retention value of 1 6 t e s t specimens at 70°F. t r e a t i n g temperature and 1 0 0 p s i . Average ;R values were taken from Table 2 , =  4.0  -x  Fig.6  on  i  c o  type  Hxh  %  2.0.  Effect  of  pressure  creosote Douglas  and  retention fir  temperature in a  mountain-  stem.  LEGEND:  x  (Til 70°F.temp., atmospheric  pressure.  Y~X 2)2° F.temp., atm. pressure. 7 0 ° F. t e m p . J O O p s i . pressure. 1.5  2l2°F.temp., 100 psi. pre ssure.  i  O I  |  X X  | Average.  X  1.0  <  X X X Sapwood S  x  1 X  k/  X  IX Heartwood D  Included Sapwood C P o s i t i on  in the  Included Sapwood B cross  section.  Heartwood A  Fig.7.  Tbe  £ o  influence  temperature in  I  a  of on  pressure creosote  mountain - type  and retention  Douglas  fir  stem.  c « <p  or  4.C Sapwood  (S)  I  3.0  2.0  Included Included  sapwood ( C ) sapwood (B)  H e a r t w o o d (A) H e a r t w o o d (D)  1.0  8z 70 I5  212 15  70 100  212 100  Temperature - F . Pressure- psi. 4  F i g . 8.  Influence on  of  creosote  Douglas  fir  pressure retention sapwood  and in and  temperature  mountain-type heartwood.  LEGEND:  1  70  212 Atmospheric Temperature -°F.  ' r  lOOps Pressure.  -33more f l u i d at higher temperatures.  Consequently, i t penetrates wood more  r e a d i l y at higher than a t lower temperatures. A d e f i n i t e r e l a t i o n s h i p between v i s c o s i t y and penetrance, which could be expressed by empirical equations f o r s p e c i f i c conditions, found by Bateman  was  (4).  A great importance i s attributed by Howald (28) to the presence o f peptized c o l l o i d s i n o i l preservatives.  The c o l l o i d s are believed to  exert t h e i r influence by changing the c a p i l l a r y r e l a t i o n s h i p between o i l and wood. Raphael and Graham (42)  confirmed Bateman*s conclusion, stating  that o i l s with low v i s c o s i t y and specific g r a v i t y are the best  penetrants.  High-viscosity, low-specific gravity o i l s penetrate better than high-viscosity and h i g h - s p e c i f i c gravity o i l s . I t was  concluded by Liese (32)  that, although the depth of pene-  t r a t i o n o f o i l y wood preservatives i s influenced by t h e i r v i s c o s i t y , surface tension, and s p e c i f i c gravity, even greater importance must be ascribed to chemical f a c t o r s , such as the chemical composition of preservative. 3.  Correlation between s p e c i f i c g r a v i t y and  permeability  The average s p e c i f i c g r a v i t y o f the f i v e zones remained f a i r l y constant  (Table 4 and Figure 9D), while the permeability of the corresponding  zones varied s i g n i f i c a n t l y .  Consequently, there was no d e f i n i t e c o r r e l a t i o n  between s p e c i f i c gravity and ease of penetration. M i l l e r (37)  recently investigated the influence of s p e c i f i c gravity  on the p e n e t r a b i l i t y of Douglas f i r , but found no c o r r e l a t i o n between the two v a r i a b l e s .  In t h e i r absorption studies of ponderosa pine with oil-base  preservatives, Brown, Moore, and Zabel (8) concluded that an increase i n the  TABLE 4 .  Some physical and chemical properties of a mountain-type Douglas f i r stem.  ^ ^ ^ P o s i t i o n i n the ~«->^cross section s  Heartwood A  Included Sapwood B  Included Sapwood C  Heartwood D  Sapwood S  1  2  .395  .403  .392  .400  .376  23  25  26  22  25  Growth rate (rings per in oh)  18.1  22.0  28.5  60.2  63.8  Fibre length (mm.)  3.03  3.48  4.15  4.11  4.14  316  90  325  226  632  Alcohol-benzene-soluble extractives (%)  4.66  1.21  2.68  7.01  2.27  Acetone-soluble extractive content (%)  3.34  1.13  2.40  6.10  1.83  Ether-soluble extractive content (%)  3.17  1.87  1.57  6.14  1.90  0.065  0.094  0.105  0.051  .304  Properties Specific gravity Percent summerwood  Number o f l o n g i t u d i n a l r e s i n ducts per sq. i n .  Creosote retention g/cm 3  3  5  4  -35-  F i g . 9 . Creosote retentions and some physical and c h e m i c a l properties of a mountaii type Douglas fir stem at five positions A . Creosote r e t e n t i o n , in the cross section.  G.  Number  A Heartwood Pith  B C 0 Included sapwood Incl. sapwood Heartwood Position  in  the  cross  section.  E Sapwood Bark.  -36-  s p e c i f i c g r a v i t y o f wood causes a s l i g h t decrease i n absorption.  This  e f f e c t decreases with an increase i n moisture content. 4.  Influence of percent summerwood on permeability There appears to be a l i n e a r c o r r e l a t i o n between percent sunmer-  wood and permeability (Table 4 and Figure 9C).  The apparent r e l a t i o n s h i p ,  however, can not be accepted as being s i g n i f i c a n t , f o r the following reasons: (i)  The average percent summerwood values o f the f i v e zones vary only  from 2 2 to 2 6 percent.  This 4 percent v a r i a t i o n between the f i v e zones i s  smaller than the 7.4 percent standard deviation o f the e n t i r e data. (ii)  The accuracy of the method used to determine percent summerwood  was approximately + 3 percent. ( i i i ) An analysis o f variance revealed no s i g n i f i c a n t differences between the percent summerwood values of the d i f f e r e n t zones. Specimens representing a much wider range of percent summerwood must be selected to investigate the influence o f t h i s factor on t r e a t a b i l i t y . The e f f e c t of percent summerwood on penetration of preservatives into Douglas f i r was investigated by M i l l e r ( 3 7 ) , who found no c o r r e l a t i o n between the two v a r i a b l e s .  5.  E f f e c t o f growth rate on creosote retention No s i g n i f i c a n t c o r r e l a t i o n between growth rate and the ease o f  penetration i s revealed i n Figure 9 B and Table 4 . The growth rate decreases from p i t h to bark, but the creosote retention values do not follow the same pattern.  Other factors seem to be of more importance i n the determination  of wood permeability. Neither Bryan (9) nor M i l l e r ( 3 7 ) found any relationship between growth rate and t r e a t a b i l i t y of wood when impregnating Douglas f i r with  -37creosote.  In t h e i r i n v e s t i g a t i o n o f l o n g i t u d i n a l penetration of creosote  in Douglas f i r , Raphael and Graham (42)  concluded that wood with high r i n g  count showed a more uniform d i s t r i b u t i o n o f preservatives than wood with a low r i n g count. 6.  Relationship between f i b r e length and creosote retention In l o n g i t u d i n a l penetration, the preservative must pass through  fewer c e l l w a l l s i n woods with long f i b r e s than i n woods with short f i b r e s per unit length.  T h e o r e t i c a l l y , a deeper penetration and a higher retention  would be expected i n the f i r s t type of wood than i n the second. The r e s u l t s of t h i s study, given i n Table 4 and Figure 9, indicate that f i b r e length i s not an important f a c t o r i n the determination o f the permeability of wood.  Any minor influence which f i b r e length may  have i s  dominated by the e f f e c t of more important f a c t o r s . 7.  Influence of l o n g i t u d i n a l r e s i n ducts on p e n e t r a b i l i t y (Table 4 and Fig. 96) Within t h i s mountain-type Douglas f i r stem no c o r r e l a t i o n was  found  between the number of l o n g i t u d i n a l r e s i n ducts and l o n g i t u d i n a l penetration. It was observed, however, that r e s i n ducts i n heartwood contained more r e s i n than those i n included sapwood. sapwood may  Consequently, the r e s i n ducts i n included  have aided penetration, whereas those i n the heartwood are l e s s  l i k e l y to have done so. Hunt and Garratt (29) heartwood r e s i n ducts may  stated that i n mountain-type Douglas f i r  be penetrated to a greater or l e s s e r extent, but  so l i t t l e preservative enters the adjacent wood c e l l s that the resultant penetration i s l i t t l e improved.  On the other hand, maximum penetration along  the r e s i n ducts of Douglas f i r was great significance to t h i s f a c t o r .  observed by Scarth (43),  who attributed  -388.  Correlation between extractive content and t r e a t a b i l i t y an There appears to be^inverse r e l a t i o n s h i p between alcohol-benzene-  soluble extractives and creosote retention i n Douglas f i r heartwood (See Figure 10).  An increase i n alcohol-benzene solubles r e s u l t s i n a propor-  t i o n a l decrease i n wood permeability.  Thus, heartwood having a high extrac-  t i v e content i s more d i f f i c u l t to impregnate with creosote than wood r e l a t i v e l y low i n extractive content.  This c o r r e l a t i o n between the two variables  did not prove to be s t a t i s t i c a l l y s i g n i f i c a n t . A s i m i l a r r e l a t i o n s h i p was obtained between acetone-soluble t i v e s and creosote r e t e n t i o n .  The  extrac-  slope o f the straight l i n e , shown i n  Figure 12, does not s i g n i f i c a n t l y d i f f e r from zero. The r e s u l t s were somewhat d i f f e r e n t with ether-soluble extractives. A hyperbolic, rather than a s t r a i g h t - l i n e , r e l a t i o n s h i p can be observed i n Figure 11.  The curve indicates that the influence of extractive content  wood permeability decreases with increasing extractive content.  on  Thus, i t may  be assumed that only a small quantity of extractives i s required to cause major changes i n the t r e a t a b i l i t y of wood.  This small amount of extractives  i n the c e l l w a l l structure appears to be adequate to close most of the channels otherwise available for l i q u i d movement.  The channels affected are  probably  the numerous c e l l wall c a p i l l a r i e s and the permanent pores i n the p i t membrane. Included sapwood contained a s i m i l a r amount o f extractives to true sapwood, and approximately one-third of that of the heartwood (Table Creosote retention of included sapwood was  4).  only one-third o f that of the  sapwood and not quite twice as much as that of the heartwood.  The amount of  extractives, as well as t h e i r l o c a t i o n within the c e l l - w a l l structure, must be considered  when studying t h e i r e f f e c t on wood permeability.  Based on the fact that sapwood and included sapwood contained s i m i l a r amounts of extractives but possessed d i f f e r e n t permeability character-  o Sapwood  Fig.  u o CO  E 2.25  10.  Correlation retention  between and  solubles  of  Douglas  fir  creosote  alcohol-benzene m o u n t a i n - type heartwood.  c o c <u - .20 a> or Y=0.114-0.009x SE .15  E  =0.0155  r = .85  .10  .05  6 7 Alcohol - benzene solubles %  vO  i  Relationship retention  and  mountain-type  between ether  creosote solubles  Douglas  fir  of  a  heartwood.  -40i s t i c s , i t may be assumed that the locations of the extractives are not the same i n the two types of wood.  This assumption i s confirmed by the fact that  the major function of sapwood i n the l i v i n g tree i s conduction, while that o f the included sapwood i s mechanical support.  I t i s probable that the extrac-  t i v e s i n both the included sapwood and heartwood are located i n such a way as to p a r t i a l l y or f u l l y seal most o f the c a p i l l a r i e s present  i n the c e l l w a l l s .  The difference between included sapwood and normal heartwood, as f a r as permeability i s concerned, may be due to the extent to which the c e l l w a l l c a p i l l a r i e s are blocked with extractives.  In included sapwood the degree of  deposition of extractives i n the c e l l w a l l c a p i l l a r i e s i s expected t o be lower than i n the heartwood.  This would be expected since the former t i s s u e has  apparently only p a r t i a l l y undergone the process o f conversion from sapwood to a heartwood.  In addition, included sapwood contains^smaller percentage o f  extractives a v a i l a b l e f o r deposition than heartwood.  This theory may be  supported by the fact that creosote retention i n heartwood was approximately h a l f o f that i n included sapwood. Stone (49) found spaces between the t o r i and the edges of the p i t aperture, when analysing photomicrographs of aspirated p i t s at high magnifications.  From t h i s f i n d i n g he concluded that the surface o f the torus was  too rough to completely seal the aperture t o the flow of most l i q u i d s .  There  i s a p o s s i b i l i t y that these openings did not e x i s t i n the o r i g i n a l wood, but were caused during the preparation o f the s l i d e s by the removal of some o f the extractives which might normally plug the openings. 9.  Improvement i n t r e a t a b i l i t y due to extraction In the previous part o f t h i s study an inverse r e l a t i o n s h i p was found  to e x i s t between extractive content and permeability.  I f this correlation i s  o  R e t e n t i o n - g r a m s / cc ro  8  —r-  ro  N>  CD  •S * • 3  CD  a  o  o Q CO  on  <  CD O O  X  -•» CD  >  en  Ol  o  CO  m " m o II •  o  =  2 * cn • p o o  o  m (A  O  CD  -N)  c  CD Q  O  o  O  C L  3  o  CT  o  mmm9 «  I  CD  a * O CD CD ©  o  CD  CO  ao  3 0)  O  > 3 S 8 c a cF  -42t r u e , an improvement i n r e t e n t i o n may  be expected upon the removal o f some  o f the e x t r a c t i v e s from the c e l l w a l l s t r u c t u r e . 5 support  t h i s assumption.  extraction.  The  extent  for  Improved p e r m e a b i l i t y was  The  obtained  i n Table  following  unextracted  average r a t i o s between t h e c r e o s o t e test  specimens were 1 . 2  8.1  f o r heartwood ^D)  (Table  4,  i t may  i n c l u d e d sapwood ( C ) , and  From t h e above f i g u r e s , and heartwood, h a v i n g  r e s u l t s given  o f t h e improvement i n p e r m e a b i l i t y v a r i e d i n t h e  d i f f e r e n t t y p e s o f wood. o f e x t r a c t e d and  The  the h i g h e s t  from T a b l e  e x t r a c t i v e content,  p e r m e a b i l i t y to the greatest extent.  retentions  f o r sapwood ( S ) ,  6.5  5). be observed t h a t  on e x t r a c t i o n improved i n  Sapwood, c o n t a i n i n g low p e r c e n t a g e s o f  e x t r a c t i v e s , increased i n t r e a t a b i l i t y very  slightly.  Included  sapwood, with  s i m i l a r e x t r a c t i v e c o n t e n t s t o t h a t o f sapwood, improved g r e a t l y i n permeability. S i n c e t h e improvement i n t h e p e r m e a b i l i t y o f sapwood and sapwood was  very.much d i f f e r e n t , i n s p i t e o f t h e i r  included  similar extractive  contents,  e i t h e r t h e l o c a t i o n o r t y p e s o f e x t r a c t i v e s o r the degree o f a s p i r a t i o n o f b o r d e r e d p i t s m u s t . d i f f e r i n the two the p r e v i o u s  k i n d s o f wood.  This observation  the  supports  assumption which a t t r i b u t e s a g r e a t s i g n i f i c a n c e to the l o c a t i o n  o f e x t r a c t i v e s i n the c e l l w a l l s t r u c t u r e . Heartwood, h a v i n g  the highest  e x t r a c t i v e content,  g r e a t e s t improvement i n t r e a t a b i l i t y on e x t r a c t i o n , confirms the amount o f e x t r a c t i v e p r e s e n t  as w e l l as  the  the f a c t t h a t  i n wood i s another major f a c t o r i n d e t e r -  mining i t s p e r m e a b i l i t y . 'The  d a t a r e v e a l no major d i f f e r e n c e s between the hot and  e x t r a c t i o n methods.  Therefore  Soxhlet  the temperature o f t h e s o l v e n t appeared t o  have no measureable i n f l u e n c e on t h e degree o f improvement i n p e r m e a b i l i t y . This i s probably  due  to the l o n g e x t r a c t i o n p e r i o d employed.  Of s o l v e n t s used  TABLE 5 .  Duration of Extraction  Average creosote retentions of mountain-type Douglas f i r heartwood, Included sapwood, and sapwood, following a 240-hour extraction i n d i f f e r e n t solvents. Kind o f wood: Included Sapwood C  Type o f Solvents  Heartwood D  Average  Extraction method:  (Hours)  Soxhlet  Hot  |  Soxhlet  Hot  (Retention -- grams) 60 60 60 60  Alcohol-benzene Ether Acetone Water  ) ) ) )  0.67  0.66  0.46  0.56  0.58  220 10 10  Alcohol-benzene Alcohol Water  ) ) )  0.69  0.53  0.56  0.45  0.55  230 10  Sodium hydroxide ) Water )  0.67  0.68  0.57  0.66  0.64  240  Water  0.65  0.67  0.67  0.62  0.65  Control (No extraction)  0.10  0.10  0.07  0.07  0.08  0.55  0.53  0.46  0.47  None  A v e r a g e: A v e r a g e: Ratio of retention o f extracted specimens to unextracted: Average r a t i o :  0.54  6.7  0.47  6.3 6.5  8.6  8.2 8.1  Water extraction, 240 hrs.; Average retention, extracted = 0 . 4 8 g.; unextracted, 0 . 3 9 g.; Ratio = 1 . 2  -44i n the extraction studies, water gave most improvement i n permeability (Table 5 ) .  The reason f o r t h i s may be that the water r e l i e v e d , p a r t i a l l y  or f u l l y , the aspiration i n the bordered p i t s , thus providing a greater number of channels for l i q u i d movement.  This i s , o f course, only an  hypothesis which could be proved or disproved by a detailed study of the degree o f a s p i r a t i o n i n extracted and unextracted matched specimens. This aspect o f the study may have some p r a c t i c a l s i g n i f i c a n c e i n the wood preserving and pulp i n d u s t r i e s . A method of pre-treatment could be developed to improve the permeability o f wood. According to the r e s u l t s obtained i n t h i s i n v e s t i g a t i o n , water would appear to be the most e f f e c t i v e , and the most economical solvent f o r extraction.  A problem i n the wood preserving industry would originate from  the large sizes of the material to be extracted, and the long periods of time required f o r solvent to reach the middle portions of what i s a r e l a t i v e l y impermeable material.  Furthermore, the use o f higher temperatures may be  necessary to increase the effectiveness of the solvent. The pulp industry, however, would not face t h i s problem as the size of the chips i s s u f f i c i e n t l y small to enable thorough extraction i n a r e l a t i v e l y short time, 10.  E f f e c t o f solvent on wood Water, at low temperatures, does not react chemically with wood.  I t s action i s confined to the removal o f some o f the water-soluble extractive content.  At elevated temperatures, water has a marked chemical effect on wood.  I t influences strength properties by breaking down some o f the pentosan and c e l l u l o s e components.  The amount o f these materials removed from the wood  depends on the s e v e r i t y of the conditions (temperature, pressure and duration of  treatment).  -45-  Neutral solvents, such as alcohol, benzene and acetone, do not a f f e c t the strength properties o f wood.  These solvents, having l a r g e r  molecular sizes than water, cannot enter the small c a p i l l a r i e s i n the amorphous region, and therefore do not rupture the secondary valence forces between the c e l l u l o s e molecules. Sodium hydroxide reacts with l i g n i n and wood carbohydrates, breaking down the basic components and causing d e l i g n i f i c a t i o n .  The  degree of d e l i g n i f i c a t i o n depends on the concentration o f the solvent and on the t r e a t i n g conditions. percent  In the extraction o f Douglas f i r wood with 0.1  sodium hydroxide, i t was observed from the reddish color o f the  s o l u t i o n , and the appearance o f the extracted specimens, that a large portion o f the l i g n i n had been removed.  The amount o f l i g n i n removed from  the t e s t specimens was not determined. 11.  Bordered p i t a s p i r a t i o n Most of the t o r i i n the bordered p i t s of sapwood, heartwood, and  included sapwood appeared to be i n an aspirated condition when observed i n 20-micron-thick  sections under a binocular microscope.  used was approximately 6 0 0 X. two  reasons.  The magnification  .'These observations may not be r e l i a b l e f o r  One o f these i s that much thinner sections, 2 microns i n  thickness, are required for the accurate i n v e s t i g a t i o n o f the degree of aspiration.  Another reason could be the possible effect of sectioning and  s l i d e preparation on the degree of aspiration observed.  The l a t t e r cause of  error probably e x i s t s i n many of the studies o f t h i s type.  Observation o f  p i t aspirations have usually been made on wood sections cut on a microtome. The disruption o f the wood structure during sectioning and s l i d e preparation should not be overlooked as a possible source o f error due to mechanical forces and chemical solvents.  -46I f the uniform aspiration of the bordered p i t s observed i n heartwood, sapwood, and included sapwood i s accepted as v a l i d , i t leads to an important  conclusion.  This i s that the a s p i r a t i o n of bordered  pits  has no e f f e c t on the permeability o f mountain-type Douglas f i r . 12.  Direction o f penetration (Figure 5) Much better penetration was obtained from the ends than from the  sides of the test specimens.  In fact, i n many specimens, complete impreg-  nation of the material was obtained when only the end grain was exposed to the creosote.  The r a t i o s between l o n g i t u d i n a l and side penetration of  the included sapwood ( B , C )  were higher than those f o r heartwood ( A , D ) .  This means that the permeability of mountain-type Douglas f i r included sapwood, along the grain, was  greater than that of heartwood.  These r a t i o s  (Figure 5), however, were considerably smaller than those given by Maclean (35).  He reported t h a t i n the very r e f r a c t o r y , Rocky Mountain-type Douglas  f i r , the l o n g i t u d i n a l penetration ranged from about 25 to 35 times as great as the side penetration, when the wood was  impregnated with creosote.  This  difference may perhaps be explained by the f a c t that the specimens used i n the present study were too short to obtain a true measure of l o n g i t u d i n a l penetration, and thus o f the r a t i o of l o n g i t u d i n a l to side penetration. In the four zones the r a d i a l penetration was  (A,C,D,S)  of t h i s mountain-type Douglas f i r stem  superior to the tangential penetration (Figure 5).  In order to f i n d an explanation f o r t h i s , an intensive anatomical study would be required.  I t may be assumed, however, that the rays and/or the r a d i a l  r e s i n ducts f a c i l i t a t e d the r a d i a l penetration (from the flat-sawn face) of creosote.  No count was made of the number of fusiform rays, nor a study of  t h e i r condition.  -47SUMMARY ' 1.  Permeability of included sapwood i s superior to that of normal heartwood, •i  but i n f e r i o r to true sapwood. 2.  The e f f e c t of pressure on creosote retention at 212°F. i s greatest f o r heartwood, l e s s f o r included sapwood, and l e a s t f o r sapwood.  The influence  of pressure on creosote absorption i n heartwood i s greater at higher temperatures than at lower ones.  Pressure has a greater effect on the  retention of sapwood at lower temperatures than a t higher ones. 3.  The influence of temperature on creosote retention i n Douglas f i r heartwood i s greater at 100 p s i pressure than at atmospheric pressure. reverse i s true f o r sapwood.  The  Temperature has a greater influence on  retention at atmospheric pressure than at 100 p s i pressure. 4.  There was no d e f i n i t e c o r r e l a t i o n between s p e c i f i c g r a v i t y of wood and ease of penetration.  5.  Percent summerwood d i d not vary s i g n i f i c a n t l y within t h i s mountain-type Douglas f i r stem,  6.  Tracheid length had no measurable influence on creosote retention i n mountain-type Douglas f i r wood,  7.  Growth rate was not found to be an important  f a c t o r i n the  determination  o f wood permeability. 8.  No r e l a t i o n s h i p was  found between the number of l o n g i t u d i n a l r e s i n ducts  and l o n g i t u d i n a l penetration of creosote, probably due to lack of length of specimens, as noted.  -489.  ( i ) A s t a t i s t i c a l l y non-significant c o r r e l a t i o n was obtained between alcohol-benzene-soluble (ii)  extractives and creosote retention.  The slope of the straight l i n e obtained for  acetone-soluble  extractives and creosote retention d i d not s i g n i f i c a n t l y d i f f e r from zero. (iii)  A hyperbolic, rather than a s t r a i g h t - l i n e , r e l a t i o n s h i p was  found between ether-soluble extractives and creosote retention.  The  higher the extractive content, the greater the retention. (iv)  Within t h i s mountain-type Douglas f i r stem the amount as well  as the l o c a t i o n of the extractives i s considered to be important i n the determination of wood permeability. 10.  Pre-treatment o f samples with d i f f e r e n t solvents i n order to remove some o f the extractives improved the permeability o f heartwood, included sapwood and sapwood.  The increases were r e s p e c t i v e l y 8.1, 6.5 ( a l l  solvents), and 1.2 (only water) times, compared with the c o n t r o l s . 11.  No d e f i n i t e conclusion can be drawn from the l i m i t e d number o f observations on the degree o f bordered p i t a s p i r a t i o n .  12.  I t would be desirable to know the effect o f extraction treatment on the c e l l walls and on the mechanical properties o f the wood.  A chemical  analysis of the solvents a f t e r the extraction treatment would show which wood components had been extracted. 13.  The development o f an e x t r a c t i o n pre-treating technique i s suggested f o r the wood preserving and pulp i n d u s t r i e s , to improve wood permeability. Type o f solvent, temperature, duration of treatment, and economics should be determined f o r s p e c i f i c conditions.  -49The specimens used i n the present study were too short to provide a true measure o f the r a t i o of l o n g i t u d i n a l to side penetration.  In  the four zones of the l o g section^ higher retentions were obtained i n the specimens when exposing the tangential faces than the r a d i a l faces.  -50R E F E R E N C E S 1.  American Society f o r Testing Materials. 1959. wood preservatives, and related materials. Philadelphia.  2.  B a i l e y , I.W. 1913. The preservative treatment of wood. Forestry Quart. 11: 12-20.  3.  ASTM Standards on wood, ASTM Committee D-7.  I and I I .  . 1957. The structure of the p i t membranes i n the tracheids o f c o n i f e r s . Holz a l s Roh und Werkstoff. 15(£): 210-213. Commonwealth S c i e n t i f i c and I n d u s t r i a l Research Organization, Trans.  No. 3639. 4.  Bateman, E. 1920. Relation between v i s c o s i t y and penetrance of creosote into wood. Chem. Met. Eng. 22: 359-360.  5.  Belford, D.S. I960. Some application of physical methods i n the study o f preservative treated wood. F i f t h World Forestry Congress. Seattle, Washington.  6.  Blew, T.O. 1955. Study of the preservative treatment of lumber. U.S. Dept. o f Agric. For. Serv., For. Prod. Lab., Madison. No. 2043. 16 pp.  7.  Brown, H.P., A.J. Panshin and C.C. Forsaith. 1949. Textbook of Wood Technology. V o l . 1. McGraw-Hill Book Co. Inc., New York, 651 pp.  8.  Brown, F.L. and R.A. Moore, R.A. Zabel. 1956. Absorption and penet r a t i o n o f o i l - s o l u b l e wood preservatives applied by dip treatment. State Univ. o f New York, College o f Forestry i n Syracuse. 38 pp.  9.  Bryan, T. 1930. Preliminary report on the creosoting of Douglas f i r sleepers. Dept. S c i . Ind. Res., For. Prod. Res. Lab. Project 0. Investigation 37. Princes Risborough, Bucks. 15 pp.  10.  Buckman, S.T., H. Schmitz and K.A. Gortner. 1935. A study o f c e r t a i n factors influencing the movement of l i q u i d s i n wood. Jour. Phys. Chem. 39: 103-120.  11.  Buckman, S.T. 1936. Creosote d i s t r i b u t i o n i n treated wood. Chem. 28: 474-480.  12.  Buro, A. and E.A. Buro. 1959. Beitrag zur Kenntnis der Eindringwege f u r Flussigkeiten i n Kiefernholz, Holzforschung, 13 (8): 71-77.  13.  Burr, A.K. and A.J. Stamm. Chem. 51 ( l ) : 240-261.  14.  Cochran, W.G. and G.M. Cox. 1950. and Sons, New York. pp. 611.  1947.  D i f f u s i o n i n wood.  Ind. Eng.  Jour, of Phys.  Experimental Designs.  John Wiley  -5115.  CSte, W.A.  and W. Liese.  membrane structure.  1958.  Electron microscope studies of p i t  For. Prod. Jour.  8(10): 296-301.  16.  Dadswell, H.E. and A.B. Wardrop. I960. Recent progress i n research on c e l l wall structure. F i f t h World Forestry Congress. Seattle, Washington. 8 pp.  17.  Eames, A.J. and L.H. MacDaniels. Anatomy.  1925.  An Introduction to Plant  McGraw-Hill Book Co., Inc., New York.  2"6-35.  p.  18.  Erickson, H.D., H. Schmitz, and Gortner, R.A. 1937. The permeability of woods to l i q u i d s and factors a f f e c t i n g the rate of flow. Univ. Minn. Agr. Exp. Stat. Tech. B u l l . 122. 42 pp.  19.  F l e i s c h e r , H.O. 1953. An anatomical comparison of r e f r a c t o r y and e a s i l y treated Douglas f i r heartwood. Proc. Am. Wood Pres. Assoc,  46: 152-156.  20.  Frosch, C.T.  1935.  Correlation of d i s t i l l a t i o n range with the i n t e r -  f a c i a l tension of creosote against water.  Physics  6: 174-177.  21.  Gerry, E. 1913. Microscopic structure of woods i n r e l a t i o n to _^ : properties and uses. Proc. of Soc. Amer. For. 8(2): 159-157. '  22.  Graff, J.R. and R.W. M i l l e r . Jour. 109(8): 31-37.  23.  Graham, H.M., and E.F. Kurth. 1949. Douglas f i r . Ind. and Eng. Chem.  1939.  Fiber dimensions.  Paper Trade  Constituents of extractives from  41: 409-414.  24.  Greaves, C. 1951. Preservative treatment o f Douglas f i r and western hemlock sleepers i n Canada. For. Prod. Lab. of Can., Ottawa. 17 pp.  25.  G r i f f i n , G.T. 1919. Bordered p i t s i n Douglas f i r : A study of the p o s i t i o n of the torus in mountain and lowland specimens i n r e l a t i o n : to creosote penetration. Jour. For. 17(2) 813-833.  26.  1924. Further note on the p o s i t i o n of the t o r i i n bordered p i t s i n r e l a t i o n to penetration of preservatives. Jour.  For. 22(6): 82-88.  27.  Harkom, T.F. 1959. L i f e of creosoted wooden p i l i n g s when used f o r b u i l d i n g foundations to support masonry f o o t l i n g s . For. Prod. Lab. of Can., Ottawa. 10 pp.  28.  Howald, A.M.  1927.  Penetrance of o i l y f l u i d s i n wood.  Chem. Met. Eng.  34: 353-355 and 413-415. 29.  Hunt, G.M. and G.A. Garratt. 1953. Wood Preservation. McGraw-Hill Book Co. Inc., New York. 417 pp.  30.  Kennedy, R.W. and J.W. Wilson. 1956. V a r i a t i o n i n t a x i f o l i n content of a Douglas f i r stem exhibiting target r i n g . For. Prod. Jour. 6(6):  230-231.  2nd  edition.  -5231.  Koljo, B. 1954. Influence o f the methods o f impregnation on the absorption o f preservatives i n wood impregnation. Holz a l s Roh-und Werkstoff. 12(1): 7-16.  32.  L i e s e , W. 1951. I he influence o f the physical properties o f o i l y preservatives on t h e i r penetration into wood. Bitumen, Teere, Asphalte, Peche und Verwandte Stoffe. 2(11): 276-279.  33.  • 1954. Fine structure of bordered p i t s i n conifer wood. Commonwealth S c i . Ind. Res. Org. Translation No. 3621.  34.  and W.A. Cote . i960. Electron microscopy of wood. F i f t h World Forestry Congress. Seattle, Washington. 6 pp. -  >  35.  Maclean, J.D. 1952. Preservative treatment of wood by pressure methods. U.S. Dept. o f Agric., Washington, D.C. Publication No. 224. 160 pp.  36.  Marts, R.O. 1955. Some structural d e t a i l s of Douglas f i r p i t membranes by phase contrast. Jour. For. Prod. Res. Soc. 5(j>): 381-382.  37. M i l l e r , D.T. I960. Permeability of Douglas f i r i n Oregon. For. Prod. Jour. 11(1): 14-16. 38.  P h i l l i p s , E.W.T. 1933. Movement o f p i t membr ne i n coniferous woods with s p e c i a l reference to preservative treatment. Forestry 6(1): 109-120.  39.  Preston, R.D. 1959. The f i n e structure o f wood with reference to  a  impregnation. 40.  1. Timb. Techn. 67(2245): 458-464.  .  impregnation.-2. 41.  1959.  The fine structure of wood with reference to  Timb. Techn. 67(2246): 502-508.  Proctor, P.B. and J.W.B. Wagg. 1947. The i d e n t i f i c a t i o n o f r e f r a c t o r y Douglas f i r by means o f growth c h a r a c t e r i s t i c s . Proc. Am. Wood Pres.  Assoc. 43= 170-175. 42.  Raphael, H.T. and R.D. Graham. 1951. The l o n g i t u d i n a l penetration o f petroleum o i l s i n Douglas f i r heartwood after a f i f t e e n minute immersion. Proc. Am. Wood Pres. Assoc. 47: 173-175.  43.  Scarth, G.W. 1928. The structure o f wood and i t s p e n e t r a b i l i t y . Paper Trade Jour. 86(17): 53-58.  44.  — and J.D. Spier. 1929. Studies of the c e l l walls i n wood. 11. E f f e c t of various solvents upon permeability o f red spruce heartwood. Trans. Roy. Soc. Can. 23: 281-288.  45.  Smith, D.M. 1955. Comparison of methods o f estimating summerwood percentage i n wide-ringed, second-growth Douglas f i r . U.S. For. Prod. Lab., Madison, Wisconsin. Dept. No. 2045 8 pp. S  46. - Smith, D.N. I960.. The permeability of wood. F i f t h World Forestry Congress, Seattle, Washington,  7 pp.  -5347. 48.  Stamm, A.J. 1929. The c a p i l l a r y structure o f softwoods. of Agric. Res. 38(1): 23-67.  Jour.  . 1946. Passage of l i q u i d s , vapors and dissolved materials through softwoods. U.S. Dept. Agr., Washington. Techn. B u l l . No. 929. 80 pp.  49.  Stone, C.D. 1939. A study on the bordered p i t s of Douglas f i r with reference to the permeability of wood t o l i q u i d s . Masters t h e s i s . University of Washington. 41 pp.  50.  Sutherland, J.W. 1932. Forced penetration o f l i q u i d s into wood and i t s r e l a t i o n to structure, temperature, and pressure. Pulp and Paper Mag. Can. 32: 163-167.  51.  Tiemann, H.D. 1909. The microscopical structure and physical condition of wood as a f f e c t s penetration by preservatives. Am. Ry. Eng. and Maint. o f Way Ass. B u l l . 107.10. 1. 638-653.  52.  Weiss, H.F. 1912. Structure of commercial woods i n r e l a t i o n to the i n j e c t i o n o f preservatives. Proc. Am. Wood Pres. Assoc. 8: 158-187.  53.  Wise, L.E. and E.G. Jahn. 1952. Wood Chemistry. 2nd ed. V o l . I and I I . Reinhold Publishing Corp., New York. 595 pp.  APPENDIX  -54-  TABLE 6 .  Creosote absorption values of mountain-type Douglas f i r sapwood.  Time (Hours)  Absorption (Grams)  0  0  1 minute  0.07  0.25  0.30  0.50  0.38  1.25  0.50  2  0.56  3  0.62  4  0.66  5  0.69  6  0.71  7  0.73  8  0.75  TABLE 7.  Position i n the Cross Section  Creosote r e t e n t i o n s i n mountain-type Douglas f i r sapwood, i n c l u d e d sapwood, and heartwood ' under d i f f e r e n t c o n d i t i o n s o f treatment. Atmospheric 70°  Direction of Penetration  Fig.l  pressure  P r e s s u r e a t 100 p s i 70°F.  212°F. Replicates 3  1 2  2  4  3  Retention  4  11  values  2  Radial Tangential Longitudinal A l l (Control)  0.36 0.43 1.38 2.01  0.58 0.30 1.37 2.15  0.33 0.38 1.88 2.14  0.68 0.14 1.90 2.36  1.88 0.52 2.01 2.49  1.57 0.66 2.01 3.74  1.37 1.12 2.06 2.24  True Heartwood  Radial Tangential Longitudinal A l l (Control)  0.02 0.02 0.21 0.26  0.03 0.03 0.23 0.29  0.09 0.04 0.21 0.27  0.07 0.03 0.20 0.31  0.05 0.04 0.17 0.30  0.15 0.06 0.25 0.30  0.05 0.08 0 . 0 2 0.09 0.10 0 . 0 3 0.25 0.29 0 . 5 4 0.23 0.29 0.64  Included Sapwood  Radial Tangential Longitudinal A l l (Control)  0.09 0.07 0.56 0.81  0.12 0.05 0.64 0.77  0.07 0.01 0.65 0.74  0.11 0.08 0.52 0.71  0.14 0.02 1.06 1.35  0.20 0.07 0.89 1.46  0.15 0.09 0.86 1.25  Included Sapwood  Radial Tangential . Longitudinal A l l (Control)  0.02 0.07 0.56 0.60  0.05 0.05 0.56 0.68  0.08 0.08 0.49 0.58  0.07 0.08 0.45 0.57  0'.1'4 0.25 1.02 1.10  Radial Tangential Longitudinal A l l (Control)  0.03 0.01 0.27 0.29  0.03 0.01 0.30 0.32  0.08 0.06 0.27 0.35  0.05 0.06 0.27 0.26  0.04 0.06 0.35 0.45  B True Heartwood  1  3  3  4  (grams)  True Sapwood  D  212°F.  1.72 4.46 4.09 4.29  1.37 4.21 4.12 3.70  3.58 4.29 4.09 4.23  3.52 4.30 4.06 4.27  2.99 3.69 3.42 3.54  3.34 3.31 3.70 3.90  0.02 0.02 0.48 0.58  0.17 0.07 0.56 0.74  0.20 0.20 0.61 0.76  0.75 0.87 1.17 1.04  0.78 0.74 1.28 1.12  1.29 0.98 1.32 1.42  1.25 1.21 1.40 1.32  0.39 0.25 1.32 1.10  0.11 0.14 1.30 0.90  0 . 1 9 0.18 0.10 0.11 1.30 1.21 1.05 0 . 8 8  1.78 0.70 2.75 1.96  2.01 0.98 2.52 2.25  1.41 1.95 2.29 2.26  1.40 1.56 2.63 2.08  0.15 0.17 0.90 1.10  0.17 0.21 0 . 1 2 0.11 0.13 0 . 1 0 0 . 9 7 0.93 1 . 0 0 1.C0 0.86 1 . 1 9  0.20 0.18 0.93 0.86  0.29 0.20 0.86 1.00  0.24 0.15 0.92 1.07  0.72 1.10 2.05 2.11  1.05 1.20 2.07 2.10  1.73 1.36 1.82 1 . 4 2 2.20 1.59 2.40 2.22  0.04 0.02 0.44 0.47  0.07 0.08 0.35 0.49  0.17 0.05 0.62 0.72  0.11 0.05 0.59 0.65  0.12 0.13 0.62 0.92  0.08 0.13 0.62 0.71  1.15 0.72 1.20 1.55  0.48 1.07 1.73 1.75  0.46 1.80 1.87 1.82  1.18 0.88 2.08 2.13  0.12 0.09 0.98 1.10  0.04 0.10 0.31 0.59  2.50-2.85 4.26 3.66 4 . 2 2 4.13 4.14 4.22  1.58 1.49 1.75 1.61  -56TABLE 8.  Analyses of variance of creosote retentions i n mountain-type Douglas f i r as affected by pressures, temperatures, p o s i t i o n , and direction of penetration.  Source  Sum o f Squares  D.f.  Mean Squares  F  1. Pressure  79.65  1  79.65  1632**  2. Temperature  23.87  1  23.87  489**  3. P o s i t i o n  193.48  4  48.37  ooi**  4. Direction  35.70  3  11.90  244**  7.48  1  7.48  153.3**  6. Pressure x position  31.46  4  7.86  161.1**  7. Pressure x d i r e c t i o n  1.68  3  0.56  11.5**  8. Temp, x p o s i t i o n  1.81  4  0.45  9.2**  9. Temp, x d i r e c t i o n  0.37  3  0.12  2.5  7.31  12  0.61  12.5**  5.82  4  1.45  30.0**  0.55  3  0.18  3.7*  0,30  12  0.69  14.1**  3.24  12  0.27  5.5**  12.35  253  5. Pressure x temp.  10. Position x d i r e c t i o n 11. Pressure x temp, x position  12. Pressure x temp, x direction  13. Pressure x p o s i t i o n x direction  14. Temp, x p o s i t i o n x direction  Error TOTAL  413.07  C  351.77  1  n.s. = non-significant  *significant  0.048814  **highly s i g n i f i c a n t  n  -57TABLE 9.  S p e c i f i c g r a v i t y values* of a mountain-type Douglas f i r stem. P o s i t i o n i n Cross Section  Replicates Heartwood (inner) A  Included Sapwood B  Included Sapwood C  Heartwood (outer) D  Sapwood S  1  0.399  0.399  0.383  0.394  0.352  2  0.397  0.406  0.398  0.392  0.397  3  0.407  0.402  0.394  0.408  0.389  4  0.376  0.403  0.394  0.406  0.367  0.395  0.403  0.392  0.400  0.376  AVERAGE:  *Based on green volume, oven-dry weight o f unextracted specimens.  -58TABLE 10.  \  Percent summerwood values of a mountain-type Douglas f i r stem and analyses of variance.  Position  Ring ^ \ number  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15  16 17 18 19 20 21 22 23 24 25  •Source Total Between Within  Included Sapwood B  Included Sapwood C  19 30 20  29 29 25  20 27  25  22  25  29  32  27 24 29  30 30 21  26 22 17 15 21 31 17  23  33 38  33 22  27 25  23  20 15 20 20 14 30  37 17 17 20 11 30 15 18  A  26 27  28 29 30 31 32  33 34 35 36 37 38 39 40 41  18 25  21 23 27  22 32  25  21 30 31 33 38  42  43 44 45 46 47 48 49 50  Sums Sum o f squares Averages Standard deviations Number  Heartwood  298 7172 22.9  25.3  5.3  4.2  13  15  Degrees  144 4 140  739 9827  Sum o f Square  7,775 493 7,282  553 15,529 26.3 6.9 21 Mean Square  123.3  52.0  Heartwood  Sapwood  D  S  25 25  33 33 14 15 25  20  25 25  15 33  33 17  25 25  29  25 25  7 14 14 20  29 25  14 20  20 20 33 33 20 33  25  25  25  13 14  17 17 33 12  33 33 33 17 33 8 21  25 25  25  20  30  14 22 13 20 30  23  50 9 10 22  25  33 40 33  17 26 20 25 25  17 25 25  18 11 22 12 33 33 29  29  1012 24,108  1228 34,180  21.5  25.1  7.0  8.4  47  49  Variance r a t i o  2.37  Not s i g n i f i c a n t  -59TABLE 1 1 .  F i b r e l e n g t h v a l u e s f o r v a r i o u s s e c t i o n s i n a mountain-type Douglas f i r stem.  Position i n - ^ ^ ^ the c r o s s ^^~^section Number^-^^^  Heartwood A  Included Sapwood B  Included Sapwood C  Heartwood  Sapwood  D  S  120  125 84 130 101 105 112 119 98  77 115 97 86 96 92 130 115 123 70 100 132 110 90 120 100 132 85 95 129  85 125 95 87 118 105 110 111 132 112 76 122 112 125 132 112 123 140 122 120  (Units) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20  51 69 85 80 70 75 78 95 82 67 92 85 66 75 63 100 70 87 78 76  106 100 83 97 74 75 87 78 86 93 95 99 97 107 82 99 58 85 87 90  83 112 109 77 98 85 107 111 108 107 122  TOTAL:  1544  1771  2113  2094  2264  Average:  77.2  88.6  105.7  104.7  113.2  mm  33.03  3.48  4.15  4.11  4.44  -60-  TABLE 1 2 .  Alcohol-benzene, acetone, and ether s o l u b i l i t y of mountaintype Douglas f i r wood.  v. P o s i t i o n i n the ^s^cross section Extractive content  B  A 1  2  1  C 2  1  S  D 2  1  2  1  2  ^ \  Alcohol-benzene solubles - %  4.61  4.71  1.06  1.36  2.60  2.75 6.96  7.06 2.25  2.29  Acetone solubles - %  3.23  3.45  1.16  1.10  2.32  2.48 6.04  6.16  1.91  1.76  Ether solubles - %  3.14  3.20  1.96  1.78  1.61  1 . 5 3 6.08  6.20 1.95  1.85  TABLE 13.  Creosote retentions o f mountain-type Douglas f i r heartwood, included sapwood, and sapwood, following a 240-hour extraction i n d i f f e r e n t solvents.  Duration o f Extraction  Type.of Solvent  Kind of Wood:  Replicates  Included Sapwood C  (Hours)  Heartwood D  1  Typed of extractions: Hot  Soxhlet  Hot  Soxhlet  Retentions (grams)  60 60 60  Alcohol-benzene Ether Acetone Water  1 2  .69 .64  .59 .73  .45 .46  .49 .62  220 10 10  Alcohol-benz ene Alcohol Water  1  .55 .51  .64 .47  .42  2  .64 .73  .48  230 10  0.1% Sodium hydroxide Water  1 2  .64 .69  .70 .65  .55:: .58  .61 .70  240  Water  1 2  .69 .61  .67 .66  .58 .76  .63 .60  1 2  .12 .10  .09  .07 .08  .07 .08  3 4 5  .09 .10  .08 .11 .12  .06 .06  .09 .06  .09  .05  60  None  Control (no extraction)  .09 0.10  AVERAGE: Sapwood - 240-hour hot water extraction Retention (grams)  Control .395 .354  .432  Extracted .448 .498  .490  .  0.07  F i g . I.  Diagram  of  a  bordered  pit  (15,25).  A.  Mix  Bordered radial  pit  seen  on  a  section.  B. B o r d e r e d  pit-pair  tangential  X  as  or  as  cross  a.  Aperture.  b.  Torus.  seen  on  either  section.  c. A n n u l u s . C. B o r d e r e d D. Front  view  membrane.  pit of  in a s p i r a t e d a  torus  and  condition. pit  Fig. 4.  Rate in  (A  E o  of  absorption  mountain - type  of  creosote  Douglas  fir  sapwood.(S) 1.0  -v3 I  Time  in  hours  Fig. 5. 2.5  The effect of direction of penetration on creosote retentions in mountain-type Douglas fir wood at 70°F. treating temperature and at atmospheric pressure.  £ a o> c 2.0  o  LEGEND;  Radial.  or  Tangential.  1.5  ,  ro I  In  all  directions.  Longitudinal 1.0  I I Average.  Sapwoo d S  Q  Heartwoo'd  Included  D  sapwood  Included sapwood  C Position  B in  the  cross  section.  Q  Heartwood A  Fig.6  4.0 -  Effect on  a*  of  creosote  type  t c 2.5 o ••?= c  pressure  Douglas  and  retention fir  temperature in a  mountain-  stem.  <o  % or  LEGEND:  2.0.  fffl 7 0 ° F . t e m p . , atmospheric  pressure  F/l 2 J 2 ° F . t e m p . , atm. pressure.  H E  7 0 ° F. t e m p . , 1 0 0 p s i . pressure.  1.5  2l2°F.temp., |  100psi. pressure.  | Average.  X 1.0  .5-  X X X X X X X Sapwood S  Heartwood D  Included Sapwood C Position  in  the  Included Sapwood B cross  section.  Heartwood A  i  VO o  i  Fig.7.  The  influence  temperature  £ o  in  a  of on  pressure creosote  mountain - type  and retention  Douglas  fir  stem.  <D  4.d Sapwood  (S)  3.0  2.0  Included Included  sapwood ( C ) s a p w o o d (B)  H e a r t w o o d (A) H e a r t w o o d (D)  1.0  70 15  212 15  70 100  212 100  Temperature - ° F . Pressure - psi.  Fig. 8.  Influence on  of  creosote  Douglas  fir  pressure  and  retention sapwood  in and  temperature  mountain-type heartwood.  LEGEND  Sapwood (S) H e a r t w o o d (H) IQO p s i . pressure  MJ2. oil o  e<  Z\1 70  7 0 ^FM^nTj3_§.LStii — r  . J U m o s pJiJL r i _ J? rJi.su re: c  212 Atmospheric Temperature - ° F .  -  lOOpsi Pressure.  -35-  Fig. 9. Creosote retentions and some physical and c h e m i c a l properties of a mountain' type Douglas fir stem at five positions A . Creosote r e t e n t i o n . frl the CTOSS S e c t i o n .  C.  Percent T3  I  summerwood. ~  o 30  E.  A l c o h o l - be n z e n e  F.  E t h e r - soluble  and  acetone-soluble  extractive  content  extractive . content  3* 9  O CO CD UJ  Number  of  resin  A Heartwood Pith  ducts  per  square  inch  B C D Included sapwood Incl.sapwood Heartwood Position  in  the  cross  section.  E Sapwood Bark.  F i g . 10.  Correlation  o o  retention  M  E  2.25  between and  solubles  of  Douglas  fir  creosote  alcohol-benzene m o u n t a i n - type heartwood.  c o  I  2  3  4  5  6 7 8 A l c o h o l - b e n z e n e solubles % .  F i g . II.  Relationship retention  o o.25  and  mountain-type  between ether  creosote solubles  Douglas  fir  of  a  heartwood.  c o c £.201  i  .15  P> I  .10  .05  7  Ether  8  solubles % .  F i g . 12.  u u  Relationship  between  retention  and  E o  extractive  content  ^.25  type  CO  i  Douglas  creosote  acetone - soluble of  fir  mountain  heartwood.  c o  Y= O.III4-O.OI0I x SE =0.0I6 E  .15  r = . 85  10  .05  6  7 Acetone solubles % .  8  

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