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Permeability of a mountain-type Douglas fir stem containing included sapwood bands 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 of British Columbia, 1959 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER in the Faculty of Forestry We accept this thesis as conforming to the required standard THE UNIVERSITY OF BRITISH COLUMBIA April , 1961 I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r a n a d v a n c e d d e g r e e a t t h e U n i v e r s i t y o f B r i t i s h C o l u m b i a , I a g r e e t h a t t h e L i b r a r y s h a l l m a k e i t f r e e l y a v a i l a b l e f o r r e f e r e n c e a n d s t u d y . I f u r t h e r a g r e e t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y p u r p o s e s m a y b e g r a n t e d b y t h e H e a d o f my D e p a r t m e n t o r b y h i s r e p r e s e n t a t i v e s . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l n o t b e a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . D e p a r t m e n t o f forestry T h e U n i v e r s i t y o f B r i t i s h C o l u m b i a V a n c o u v e r C a n a d a . ' I. ABSTRACT Penneability to creosote of sapwood, included sapwood, and normal heartwood of a mountain-type Douglas f i r stem was correlated with specific gravity, growth rate, percent summerwood, tracheid length, number of longi- tudinal resin ducts, alcohol-benzene, acetone and ether-soluble extractive contents of the corresponding zones. The effect of pressure and temper- ature on creosote retention was tested on creosote retention i n true sapwood, included sapwood (abnormal heartwood), and normal heartwood. Test specimens were extracted i n different solvents and ease of penetration tested by creosote impregnation. Among the factors investigated in the present study, specific gravity, tracheid length, growth rate, and number of longitudinal resin ducts did not have a measurable influence on creosote retention. Percent summei*wood did not vary significantly at the five positions tested. Pressure had the greatest effect on creosote retention at 212°F. for heartwood, less for included sapwood and least 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. The effect of alcohol-benzene and acetone-soluble extractives on wood permeability was not proven s t a t i s t i c a l l y significant. A visual hyperbolic relation- ship was obtained between ether-soluble extractives and wood permeability. The higher the extractive content, the greater the retention. Pre-treatment of samples with different solvents, i n order to remove some of the extrac- tives, improved the permeability of heartwood and included sapwood s i g n i f i - cantly but caused only a slight improvement in sapwood. XX. CONTENTS Page_ INTRODUCTION..... 1 LITERATURE REVIEW 2 1. Physical and Chemical Structure of Douglas F i r Wood 2 (a) Physical properties 2 (b) Chemical structure..... 7 2. General 9 MATERIAL AND METHODS 12 1. Material 12 2. Methods 13 A. Absorption Studies 13 (a) Preparation of test specimens 13 (b) Conditioning to 14 percent moisture content. 13 (c) Sealing 14 (d) Treatment conditions 15 (i) Pressure. 15 ( i i ) Temperature 15 ( i i i ) Duration of treatment............... 15 (e) Preservative..... 18 (f) Measurement of absorption IS B. Determination of Some of the Physical and Chemical Properties of Wood * 18 (a) Physical properties '. 18 (i) Specific gravity 18 ( i i ) Percent summerwood 18 ( i i i ) Growth rate 19 (iv) Tracheid length 19 (v) Longitudinal resin ducts 19 (b) Chemical properties. 19 C. Extraction Prior to Impregnation 20 (a) Preparation of test specimens 20 (b) Extractions 20 (i) Alcohol-benzene(1:2), ether, acetone, and hot water extraction 21 ( i i ) Alcohol-benzene 21 ( i i i ) 0.1$ Sodium hydroxide extraction 21 (iv) Water.......... 21 (c) Conditioning to 14$ moisture content 21 (d) Sealing 22 (e) Measurements of absorption after extraction. 22 i i i Page D. Microscopic Studies.................... 22 (a) Preparation of slides.... 2 2 (b) Microscopic observations 22 RESULTS 22 A. Absorption Studies.... 22 B. Physical and Chemical Properties of the Wood 23 (a) Physical properties 23 (i) Specific gravity.. 23 ( i i ) Percent summerwood. 23 ( i i i ) Growth rate '. 23 (iv) Resin ducts 23 (v) Fibre length 2 4 (b) Chemical properties 2 4 C. Extraction Studies 2 4 DISCUSSION 2 4 1 . Effect of pressure on creosote retention 2 4 2 . Influence of temperature on creosote retention 28 3 . Correlation between specific gravity and permeability.......... 3 3 4 . Influence of percent summerwood on permeability ; 36 5 . Effect of growth rate on creosote retention 3 6 6 . Relationship between fibre length and creosote retention 3 7 7 . Influence of longitudinal resin ducts on penetrability 3 7 8 . Correlation between extractive content and treatability 3 8 9 . Improvement in treat a b i l i t y due to extraction 4 0 1 0 . Effect of solvent on wood 4 4 1 1 . Bordered p i t aspiration 45 1 2 . Direction of penetration 46 SUMMARY 4 7 REFERENCES 50 APPENDIX 54 i v . FIGURES Page, 1. Diagram of a bordered p i t 4 2. A section of an interior-type Douglas f i r timber.... 13 3. A small pressure retort 16 4. Rate of absorption of creosote in mountain-type Douglas f i r sapwood 17 5. The effect of direction of penetration on creosote retentions in mountain-type Douglas f i r wood at 70°F. treating temper- ature and at atmospheric pressure 27 6. Effect of pressure and temperature on creosote retention in a mountain-type Douglas f i r stem 30 7. The influence of pressure and temperature on creosote reten- tion in a mountain-type Douglas f i r stem 31 8. Influence of pressure and temperature on creosote retention in mountain-type Douglas f i r heartwood and sapwood 32 9. Creosote retentions and some physical and chemical properties of a mountain-type Douglas f i r stem at five positions in the cross section 35 10. Correlation between creosote retention and alcohol-benzene solubles of mountain-type Doulgas f i r heartwood 39 11. Relationship between creosote retention and either-soluble extractive content of mountain-type Douglas f i r heartwood 39a 12. Relationship between creosote retention and acetone-soluble extractive content of mountain-type Douglas f i r heartwood Al v. TABLES Page 1. The over-all composition of Douglas f i r heartwood 8 2. Average creosote retentions of the five zones of a mountain- type Douglas f i r stem under different conditions of treatment... 26 3. Effect of pressure and temperature on creosote retention i n mountain-type Douglas f i r 29 4. Some physical and chemical properties of a mountain-type Douglas f i r stem. 34 5. Average creosote retentions of mountain-type Douglas f i r heart- wood, included sapwood and sapwood, following a 240-hour extrac- tion in different solvents 43 6. Creosote absorption values of mountain-type Douglas f i r sapwood. 54 7. Creosote retentions in mountain-type Douglas f i r sapwood, included sapwood, and heartwood under different conditions of treatment 55 8. Analysis of variance of creosote retention in mountain-type Douglas f i r as affected by pressure, temperature, position and direction of penetration • 56 9. Specific gravity values of a mountain-type Douglas f i r stem 57 10. Percent summerwood values in mountain-type Douglas f i r stem and analysis of variance 58 11. Fibre length values for various sections i n a mountain-type Douglas f i r stem 59 12. Alcohol-benzene, acetone, and ether so l u b i l i t y of mountain-type Douglas f i r wood 60 13. Creosote retentions of mountain-type Douglas f i r heartwood, included sapwood, and sapwood following a 240-hour extraction in different solvents 61 ACKNOWLEDGEMENTS The author wishes to express his gratitude to Dr. R.W. Wellwood and Mr. R.W. Kennedy, of the Faculty of Forestry, The University of B r i t i s h Columbia, for their constructive direction and helpful cr i t i c i s m . Special thanks are due Mr. R. Buff, Manager of the Buff Lumber Company, Westwold, British Columbia for supplying the material used in this project. The author would also l i k e to gratefully acknowledge the help given by the Vancouver Laboratory, Forest Products Research Branch, Canada Department of Forestry, for the free use of their f a c i l i t i e s . INTRODUCTION The movement of liquids i n wood is of great interest to several branches of the wood Industry. It i s particularly so in wood preservation, fire-proofing, dimensional stabilization, pulp and paper manufacturing, and also in the drying, gluing, and finishing of wood. During the past 60 years a considerable amount of work has been done on the evaluation of the factors affecting the penetration of preser- vatives, especially creosote, into Douglas f i r timber. As a result of these experiments a great improvement can be seen in the techniques for impreg- nating Douglas f i r with o i l - and water-borne preservatives. However, there s t i l l remains a great deal of research work to be done in this f i e l d . It is a well known fact that Douglas f i r sapwood can be impreg- nated with preservative liquids more easily than the heartwood. In addition, preliminary tests performed by the author this year indicated that the perme- a b i l i t y of certain portions of Douglas f i r heartwood is 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 fact zones of included sapwood. This recent observation of the superior permeability of included sapwood (abnormal heartwood) over that of the normal heartwood, offers a completely new approach to the investigation of some of the factors affecting the penetration of creosote into Douglas f i r . The present investigation may be divided into three major parts. The object of the f i r s t part was to deteraine the pattern of absorption of creosote at different points i n a section of a log of interior Douglas f i r containing included sapwood bands. Various treatments were used to investi- gate the effect of pressure and temperature on the penetration of creosote into this material. -2- The purpose of the second part was to determine some of the physical and chemical properties of the end-matched specimens used for the absorption studies. The physical properties investigated were specific gravity, growth rate, percent summerwood, number of longitudinal resin ducts per unit of cross section area, and fibre length. Of the chemical properties, the quantities of alcohol-benzene, acetone and ether solubles were deter- mined. This enabled a correlation to be made of the pattern of absorption with the physical and chemical properties of the appropriate wood specimens. In the third part of the study, wood blocks, similar to those used in the f i r s t part of the study, were extracted with several organic solvents for a standard period of time. Following extraction the specimens were treated with creosote and the ease of penetration determined i n order to test the hypothesis that the extractive content of the material affected i t s penetrability. LITERATURE REVIEW 1. Physical and Chemical Structure of Douglas F i r Wood (a) Physical properties (7) Douglas f i r wood is composed of two major types of elements, longitudinal and transverse. T he longitudinal elements consist primarily of wood tracheids and secondly of epithelial parenchyma cells of the resin canals. These longitudinal elements constitute over 90 percent of the volume of most softwoods. The tracheids are hollow cellulosic tubes tapered and closed at both ends, and somewhat rectangular or e l l i p t i c a l in cross-section (13)• The individual tracheids are connected with each other by bordered pits, which are hence important for the movement of liquids both i n the livi 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 fine structure of the p i t membrane of bordered pits since the preserving l i q u i d must pass through the permanent pores of this membrane. The pits are located on the radial walls of the springwood tracheids, and are concentrated towards the ends. They occur mainly in a single v e r t i c a l row on the c e l l wall, but occasionally form double rows. The pits in the summerwood zone are less numerous, smaller in size and may be located on both the tangential and radial walls, depending upon the particular species. The bordered p i t has an overhanging rim, more or less circular in surface view, and the p i t i s divided by the closing apparatus. The closing membrane consists of the torus and the p i t membrane. The torus i s circular i n outline, and i s of sandwich construction. The thin middle lamella i s held between, or holds together, the two primary wall thickenings. The p i t membrane consists of a network of cellulosic filaments radiating from the torus to the margin of the p i t cavity. The filaments appear to arise from the two faces of the torus and to be made of microfibrils joined into coarser strands (15, 17, 25, 26, 33, 34, 36). Springwood c e l l s are characterized by relatively thin walls, with rather long overhanging pi t borders, whereas the summerwood c e l l s have thick walls, small p i t cavities and thick, short t o r i . Stamm (48) measured the size of the permanent pores i n the pit membrane by physical methods, and reported an average pore diameter of 28.2 millimicrons. Buckman and associates (10) found that the effective diameters of the permanent pores i n the pit membrane vary with the moisture content of the wood. Below the fibre-saturation point the effective pore diameter F i g i . Diagram of a bordered pit (15,25). / "S \ 7 \ / A. Bordered pit as s een on o r a d i a l sect ion. B. Bordered pit -pair as seen on either tangential or cross section a. A p e r t u r e . b. Torus. C. Annu lu s . C. Bordered pit In a sp i r a ted condition. D. Front v iew of o to ru s and pit membrane . decreases with increasing moisture content. Recent results obtained by- Smith (46) indicated that the average size of the openings controlling flow through certain softwoods i s equivalent to a diameter of about 2-3 microns. Marts(36) reported an average diameter of 23 microns for the border, U microns for the torus and 7 microns for the aperture of the Douglas f i r bordered p i t s . In Douglas f i r , longitudinal parenchyma cells are quite sparse and scattered throughout the growth rings. Their function in the l i v i n g tree i s to store reserve food and extractives. The parenchyma cells can be identified by their f l a t , blunt ends and the presence of simple pits i n the c e l l wall. Overhanging rims, p i t cavities, and t o r i are lacking i n these simple p i t s . Thus simple p i t pairs are merely round holes i n the contig- uous c e l l walls, with a dividing membrane between. Epith e l i a l parenchyma cells lining the ve r t i c a l resin ducts are found in Douglas f i r . The resin ducts are postcambial in formation and occur only as intercellular spaces in the wood. The transverse or radial wood elements are the wood ray c e l l s . Wood rays are of two different types, uniseriate and fusiform. The uni- seriate rays are generally one c e l l i n width and from one to many cells i n height. In Douglas f i r , ray tracheids form the marginal c e l l s of the ray, and the other cells are parenchymatous. The fusiform ray consists of the same elements as the uniseriate with the addition of epithelial cells that surround a transverse resin duct. As a result, these rays are several c e l l s wide in the middle and taper to one c e l l i n width at the margins. The main functions of wood rays are food storage and translocation from the inner bark to the l i v i n g c e l l s in the tree stem. -6- The stem is built up of growth rings or annual rings, normally one being formed every year. Each growth ring contains two distinct 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 in the latter part of the growing season, thick-walled tracheids are formed. The abrupt transition 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 distinct in 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 in the heartwood portion of the stem are dead and their function i s mechanical support. In the sapwood the tracheids die shortly after they are formed, but s t i l l function as conducting elements. As new cells are continually formed by the cambium, and added to the sapwood, a proportionate number of the old sapwood ce 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 liquids than the sapwood c e l l s . In addition, they lose a l l their functions except mechanical support. In the case of the so-called included sapwood, the conversion of sapwood to heartwood appears to be incomplete. This assumption is confirmed by the low extractive content, and by the lack of coloring matter in the included sapwood zones. Certain changes take place i n wood during the conversion of sapwood to heartwood. Numerous pits become aspirated. A bordered pit becomes aspirated when the torus moves to one side of the pit cavity and closes the p i t aperture. In addition, resins and other extractives present in the sapwood usually become hard and remain deposited within the resin ducts and c e l l lumina in the heartwood. However, no basic change takes place in the structure of the wood. (b) Chemical structure Chemically, the f u l l y matured c e l l wall consists of varying amounts of cellulose, l i g n i n and non-cellulosic polysaccharides. Cellulose is the skeleton around which the other substances are deposited. This substance i s considered to consist of long molecular chains of glucose residues. The long chains of cellulose molecules in the c e l l walls are par a l l e l over at least part of their length. In these zones of parallelism the units of glucose anhydride are bonded lengthwise as well as crosswise. The parallel replication of the cellulose chains builds up the whole crystalline structure of cellulose. Between the crystallites i n the amorphous regions, the cellulose 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 greatly reduced. The advent of electron microscopy and i t s application to c e l l wall studies revealed the presence of well defined units called microfibrils, which in different cellulosic o o materials average approximately 200 A in breadth and vary from 25 - 100 A in thickness (15)• These microfibrils are of indefinite length and are appar- ently somewhat rectangular i n cross-section. Frey-Wyssling, as stated in Dadswell (16), further suggested that a m i c r o f i b r i l , with a cross-section of o 100 x 200 A, consists of four so-called elementary f i b r i l s each containing a crystalline core, separated from each other by regions of lower order of c r y s t a l l i n i t y . Most of the non-cellulosic polysaccharides, and l i g n i n , are packed between the microfibrils. -s- Extraneous components can be subdivided into two groups. The f i r s t group, called "extractives", i s composed of chemicals which can be removed easily by neutral solvents. Among these extractives are substances such as resin acids, colouring matter, and waxes. The second group consists of miscellaneous components such as starch grains, s i l i c a , and calcium oxalate crystals. These are substances which cannot easily be removed by solvents, but nevertheless are quite distinct from the c e l l walls. Extractives are generally found in the c e l l cavities. They may also be present in very fine capillaries of the c e l l wall, thereby making their complete removal impossible. The over-all percentage composition of Douglas f i r heartwood was deterniined by Graham and Kurth (23). The sample was taken from a wide- ringed, freshly-cut, second-growth Douglas f i r . The extractive contents were based on the oven-dry weights of the unextracted wood and were deter- mined successively for ether, alcohol, and hot-water-soluble extractive. Other components of wood were based on the weights of oven-dry extracted wood. Their results are shown in Table 1. TABLE 1. The over-all composition of Douglas f i r heartwood (23). Extractives and constituents Percentage Moisture 9.10 Ether solubility 1.32 Alcohol s o l u b i l i t y 5.46 Hot-water-solubility 2.82 Total extractives: 9.60 Ash 0.175 30.15 29.35 71.40 10.11 4.75 Lignin (total sample) (40-60 mesh sample) Holocellulose Pentosan Methoxyl -9- 2 . 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 checks in the tracheid walls, thus producing means of penetra- tion. 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 thick- walled 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, in 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 tori in the bordered pits was studied by Griffin ( 2 5 ) , Shefound that the majority of the tori 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 tori 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 . -10- P h i l l i p s (38) substantiated Griffin's findings and believed that the aspiration was due to the loss of the last trace of free water i n the c e l l . He found that a l l the springwood pits became aspirated upon drying, but a portion of the summerwood pits remained unaspirated. This was explained by the difference in r i g i d i t y of the summerwood and springwood p i t membranes, and by the size of the p i t apertures. In 1936, Stone (49) investigated the bordered pits of Douglas f i r . No relationship was found between the degree of aspiration of the pits and the penetrability of liquids into the wood. The majority of the t o r i appeared to be i n a completely aspirated position when he observed 2-micron- thick Douglas f i r sections under a compound binocular microscope at 440 X magnification. However, by means of photomicrographs taken in ultra violet 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 their surfaces were not smooth, but were quite irregular in 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 findings were confirmed by Erickson, Schmitz and Gortner (18). They concluded that either p i t aspiration does not occur as extensively as reported in the literature, 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 cell-wall capillaries, and only a small portion goes through the bordered p i t s . He supports this statement by the fact that the number of transient cell-wall - 1 1 - capillaries far exceeds the number of permanent pores in the pit membranes. According to Stamm ( 4 8 ) , the fractional cross-sectional area of the transient c e l l wall capillaries i s of the order of 0 . 1 , whereas that of the permanent pores of the pit membrane i s of the order of 0 . 0 0 4 . Taking the above factors into consideration, he attributes a minimum importance to the aspir- ation of bordered pits i n determining the permeability of wood to water or similar liquids. Proctor and Wagg (41) found that the number of resin ducts per unit area in the coast-type Douglas f i r was seven times that of the mountain- type Douglas f i r . They also found more longitudinal resin ducts in the wider growth rings and concluded that there may be a relationship between tr e a t a b i l i t y and the number of resin ducts. Fleisher ( 19) related permeabilf. i t y of Douglas f i r to lumen cross-sectional area and fibre length. He found the lumen cross-sectional area to be larger in permeable Douglas f i r than in the impermeable type. Summerwood i s generally more permeable than springwood i n Douglas f i r heartwood. Earlier investigators ( 2 5 , 26, 3 0 ) explained this by the displacement of t o r i to a greater degree i n springwood than i n summerwood. The following reasons may account for the difference in permeability of springwood and summerwood: (1) The resin ducts were found to be localized mainly in the summerwood zones of the growth rings. ( 2 ) The bordered pits i n the summerwood tracheids are smaller and fewer i n number than in the springwood fibres, but they often occur as p i t canals with the torus in the dividing membrane apparently lacking ( 7 ) . - 1 2 - (3) The summerwood lumlna are also smaller than springwood lumina, and capillary action of the preservative may account for greater penetration. (4) Weiss (52) suggested that the dense, thick-walled summerwood tracheids check more readily than the l i g h t , thin-walled spring- wood c e l l s , thus accounting for the greater penetration of creosote i n summerwood. It was suggested by Buro and Buro (12) that the position of the torus is not the only factor responsible for penetrability. They attribute some significance to the substances deposited in the c e l l wall. M i l l e r ( 37 ) , based on his studies of the permeability in Douglas f i r , arrived at a similar conclusion. He states that permeability may be associated with both the minute structure and the chemistry of wood. MATERIAL AND METHODS 1 . Material A four-foot section of a green Douglas f i r (Pseudotsuga menziesii (Mirb.) Franco) log, 20 inches i n diameter, and about 340 years old, was used for this investigation. The log, as viewed in the cross section,displayed a "target ring" pattern of heartwood and included sapwood zones (Figure 2 ) . The material was free from surface defects and had a slope of grain less than one i n twenty. The tree was cut approximately 12 miles southeast of Kamloops, at an elevation of 3500 feet, and therefore represents the mountain-type (or interior-type) of Douglas f i r . -13- Figure 2. A section of an interior-type Douglas f i r timber. 2. Methods A. Absorption Studies (a) Preparation of test specimens. Since the Douglas f i r log section contained two included sapwood bands, one set of three side-matched specimens of £" x x 36" was prepared from the true 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 carefully prepared in such a way that each would contain the same annual rings. Eighty £-inch cubes were then prepared from each of the five sets and labelled simultaneously, (b) Conditioning to 14 percent moisture content. Following preparation, the test specimens were placed in an electrically-controlled conditioning -14- chamber. A constant relative humidity of 74 percent was maintained in the conditioning chamber, at 74°F. dry-bulb and 68°F. wet-bulb temperature. Test samples were removed from the chamber periodically, and their moisture contents determined. Six weeks was adequate to obtain a uniform equilibrium moisture content of 14 percent i n a l l test specimens. (c) Sealing. To measure the amount of creosote absorbed in radial, tangen- t i a l , and longitudinal directions, the appropriate face of the cubes was l e f t unsealed and the remaining five faces sealed. Five sides of the test specimens (rather than four) were sealed, in order to provide a more reliable measure of longitudinal penetration i n the relatively short specimens. The control specimens were sealed on three neighbouring sides and l e f t open on the opposite sides. It was necessary to sand the blocks before sealing i n order to prevent the formation of channels which would permit the movement of liq u i d under the sealer. The test specimens were numbered with a red wax pencil before the application of the sealer, for easy identification after treatment. The sealer was made by dissolving a plastic material (in this case a plastic ruler) i n acetone. The viscosity of the solution was regulated by the addition of solvent. The sealer was spread onto the blocks with paint brush. Several coats were applied in order to provide a continuous film over the end-grain surfaces of the test specimens. The f i r s t coat of sealer applied was a solution of low viscosity. 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 aid i n the escape of air from the surface of the wood, which would otherwise appear under the sealer in the form of air bubbles. The following coats were of a higher viscosity solution. The evaporation of acetone from each coating took approximately five minutes. -15- (d) Treatment Conditions (i) Pressure Two pressures were employed to treat 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 effect of high pressure and temper- ature might have caused collapse in the wood specimens. The pressure treat- ment was done at the Vancouver Laboratory, Forest Products Research Branch, Canada Department of Forestry, using the small pressure retort shown in Figure 3. ( i i ) Temperature Half the blocks were treated at room temperature (70°F.) and the other half at the boiling point of water (212°F.). The 212°F. temperature of the preservative was maintained by keeping the treating apparatus in boiling water for the entire treating period. ( i i i ) Duration of treatment An 8-hour time period was applied in 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 of a scale in such a way that the specimen could be immersed i n creosote. Immediately after the immersion, the submerged weight of the specimen and attachment was deter- mined to the nearest centigram. Weight readings were then taken at 15-fflinute intervals for the f i r s t 2 hours and hourly for the next 8 hours. Since the volume of the specimen presumably remained constant, the increase in weight was equal to the amount of creosote absorbed by the wood. Absorption values, reported i n Table 6, were plotted against time and the 8-hour treating period determined from the graph on Figure 4. -16- Figure 3. A small pressure retort. F i g . 4 R a t e o f a b s o r p t i o n o f c r e o s o t e i n m o u n t a i n - t y p e D o u g l a s f i r s a p w o o d . ( S ) ->3 I 7 Time in hou rs - 1 $ - (e) Preservative Coal-tar creosote was used in this investigation. Creosote was taken from the same source throughout the experiment in order to eliminate errors introduced due to viscosity and specific gravity differences. (f) Measurement of absorption Following the sealing process the test 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 (70°F.), the second at atmospheric pressure and 212°F temperature, the third at 1 0 0 p s i pressure and 70°F., and f i n a l l y the fourth group at 100 psi pressure and 212°F. The excess creosote was removed from the specimens and their weight redetermined. The amounts of creosote., retained i n the wood specimens in grams, were calculated and recorded (See Table 7 ) . B. Determination of Some of the Physical and Chemical Properties of Wood (a) Physical properties (i) Specific gravity. Four test specimens were taken from each of the five groups of specimens and their specific gravities determined using the water displacement method ( 7 ) . ( i i ) Percent summerwood. Five end-matched wood blocks were taken from the test specimens used in the absorption studies. Each block was aspirated for approximately 1 0 hours before 30-micron transverse sections were cut on a sliding microtome. Slides were then prepared from the sections. Mork's definition, which states that summerwood starts where twice the double radial tracheid wall thickness equals the radial diameter of the lumen, was considered the point of i n i t i a t i o n of summerwood ( 4 5 ) . -19- ( i i i ) Growth rate. The slides prepared for percent summerwood deter- minations were used to measure the number of rings per radial inch. (iv) Tracheid length. Match-stick size pieces were split from each of the five samples i n such a way that each included the f u l l range of growth rings. The samples of each group were boiled in separate test tubes for a period of four hours i n a solution of equal volumes of glacial acetic acid and hydrogen peroxide. Following the maceration, the pulp was washed over- night in running water. The fibres were stained, then dehydrated, using a slow alcohol series. Two slides from each of the five groups were prepared for tracheid length determination. Ten tracheids were measured on each slide and 20 from each group. 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 resin ducts. The total number of longitudinal resin ducts was determined on each slide prepared for percent summerwood deter- mination. Th'ê  area of each section was then measured and the number of resin ducts per square inch computed. (b) Chemical properties In the course of t h i s part of 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 true heartwood, and samples "B" and "C" from the included sapwood (Figure 2). Alcohol-benzene, acetone, and ether-soluble extractive contents of the five sets of samples were determined i n accordance with Tappi Standards T6-m 59-and.-T5-m 59, respec- tively (1). The extractive content of wood was reported as percentage by weight of the soluble matter i n the moisture-free wood. Two determinations were performed in each case, and the results recorded as the averages of the two -20- values. C. Extraction Prior to Impregnation (a) Preparation of test specimens Samples were taken from the sapwood (S), included sapwood (C), and true heartwood (D) zones (Figure 2) . End-matched specimens, ff-inch in cross-section and \ inch along the grain, were prepared from each zone and numbered simultaneously. Each sample was then sanded on a belt sander and inspected for natural defects. A to t a l of 58 specimens was prepared (See Table 13). (b) Extractions One-third of the test specimens from each zone (eight) were treated with various organic solvents, using the Soxhlet extraction method; another third by the hot extraction method^ while the remaining third controls were not treated. For the Soxhlet-type extraction, the wood blocks were placed i n the Soxhlet apparatus, and the solvent in the flask boiled briskly in order to ensure six to eight siphonings per hour. In the hot extraction method, the wood blocks were boiled i n various solvents, which were changed periodically to maintain their effectiveness. The detailed set-up of the extraction study i s presented i n Table 13. A standard extraction period of 240 hours, or 10 days, was used for both types of extraction. The 240-hour period was chosen in order to ensure that a sufficient length of time was allowed for the solvent to reach the middle portions of the relatively impermeable heartwood. The dimension of the test specimens along the grain was reduced from ^ inch to •§• inch, in order to improve the longitudinal penetration of the solvent. These solvents were alcohol-benzene (1:2), acetone, ether, sodium hydroxide {0.1%) and water. The effect of the extraction period was not undertaken in this 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 of 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 total of 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, acetone and water. The period of extraction in each solvent was 60 hours, giving a t o t a l of 240 hours. ( i i ) Alcohol-benzene. The test specimens were extracted i n alcohol- benzene (1:2) for 220 hours, in alcohol for 10 hours and f i n a l l y boiled i n water for another 10-hour period. The purpose of the 10-hour extraction in ethyl alcohol was to remove the benzene from the wood, and the water extraction, to replace the alcohol with water, ( i i i ) 0.1% Sodium hydroxide extraction. This solvent was used to remove or change some of the carbohydrates and lignin in the wood in order to improve i t s permeability. The specimens were extracted i n the solvent for 230 hours, and i n water for an additional 10-hour period. The purpose of water extraction was to remove the residual sodium hydroxide from the wood. (iv) Water. The total extraction time in water was 240 hours, or 10 complete days. (c) Conditioning to 11$ moisture content Following extraction, both the extracted and unextracted test specimens were placed in an electrically-operated conditioning chamber. -22- This chamber was set at 74°F. dry-bulb and at 68°F. wet-bulb temperature, which provided a 74 percent relative humidity. This in turn brought about 14 percent equilibrium moisture content in the wood. (d) Sealing Following conditioning, the end grains of the test specimens were sealed with plastic sealer i n the manner previously described. (e) Measurements of absorption after extraction Both the extracted and unextracted test specimens were weighed. They were then submerged in creosote at room temperature and atmospheric pressure, for an eight-hour period. After this treatment the excess creosote was removed from the surface of the blocks and their weights determined. Retention values were then calculated and recorded (see Table 13). D. Microscopic Studies (a) Preparation of slides Twenty-micron thick tangential sections were cut on a sliding microtome from each of the five zones. The sections were stained with analine safranin stain, 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 aspir- ation in the 20-micron tangential sections. Approximately 600 X magnification was used in this study. RESULTS A. Absorption Studies Creosote retention values of the specimens are included in Table 7. The average values are presented i n Table 2. The effect of direction of -23- penetration on retention values for one set of teat ..conditions is shown in Figure 5. The influence of pressure and temperature on creotote retention in samples tested is given in Table 3, and in Figures 6, 7, and 8. An analysis of variance for a l l the retention data is 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 fairly constant. No major difference was found between the specific gravities of heartwood and included sapwood zones. (ii) Percent summerwood. Percent summerwood values are shown in Tables 4 and 10, and in Figure 9C. The average value remained fairly 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. ( i i i ) Growth rate. Table 4 contains the average growth rate values of the five zones. 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 is recorded in Table 4 and in Figure 9G. No definite pattern could be observed in the cross section. - 2 4 - (v) Fibre length. The tracheid length values are presented in Tables 4 and 1 1 , and i n Figure 9B. Tracheid length increased from pith to bark at a f a i r l y steady rate. A slight 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 in Tables 4 and 1 2 and Figure 9F. Correlation between the extrac- tive contents and creosote retentions are presented in Figures 1 0 , 1 1 , and 1 2 . Each of the five wood samples contained a greater amount of alcohol- benzene-soluble extractives than either acetone or ether solubles. In a l l three 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 and atmospheric pressure, are presented i n Table 1 3 . Average values calculated from Table 13 are entered in Table 5 . The ratios between the retention values of extracted and unextracted specimens for sapwood, included sapwood, and heartwood were 1 . 2 , 6 . 5 , and 8.1 respectively. Greatest improvement in penetrability resulted from extraction with water. Permeability increase was slightly less with 0 . 1 percent sodium hydroxide, least with extraction i n alcohol-benzene alone. DISCUSSION 1 . Effect of pressure on creosote retention At a temperature of 2L2°F. and pressure of 1 0 0 psi, an average retention of 1 . 11 grams was obtained for heartwood (D) (Table 2 ) . At the -25- same temperature, but at atmospheric pressure, the retention was only 0.17 grams. Consequently, the specimens treated at 100 p s i pressure absorbed 553 percent more creosote than those at atmospheric pressure. Similar calculations were performed for the other zones and the results, i n percent- ages, entered in Table 3. An increase in retention of 208 percent was obtained in included sapwood (C) and 115 percent in sapwood. From the above data, and from Figures 6,7 and 8, i t may be observed that the effect of pressure on creosote retention i s greatest for heartwood (D), less for included sapwood (B and C), and least for sapwood. The influence of pressure at 70°F. on creosote retention is some- what different than at 212°F. Only 150 percent increase in retention was obtained for heartwood (D), 78 percent for included sapwood (C) and 216 percent for sapwood. This would indicate that the influence of pressure on creosote absorption in heartwood i s greater at higher temperatures than at lower ones. The opposite holds for sapwood. Pressure has a greater effect on retention at lower temperatures than at higher ones. Consequently, the application of high (treating) pressures and temperatures appears to be more advantageous for heartwood than for sapwood. In sapwood the influence of pressure on retention is far greater than that of the temperature. Hence in the treatment of sapwood, the treating pressure is the dominant factor, with l i t t l e significance attached to the temperature. In the case of heart- wood, however, both the treating pressure and temperature are of major importance. When treating sapwood under high pressure, a rise in temperature does not seem to be economically j u s t i f i e d . In practice, however, the narrow sapwood band is rarely, i f ever, treated without the heartwood. On the other hand, often the wood preserving industry i s only interested in impregnating the sapwood. -26- TABLE 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 Cross- section Pressure Atmospheric 100 psi Averages Temperature 70°F. 212°F. 70°F. 212°F. Direction of Penetration (Retentior I - grams) True Sapwood S Radial Tangential Longitudinal Al l (control) A v e r a g e 0.49 1.50 0.31 0.80 1.63 2.04 2.17 2 .65 1 .15 1.75 2.12 3.36 4.15 3 . 9 0 4.15 3.82 4.09 4.00 3.63 3.77 1.87 2.29 2.91 3.23 2.58 True Heartwood (outer) D Radial Tangential Longitudinal All (control) A v e r a g e 0.05 0.08 0.03 0.07 0.21 0 .24 0.28 0.28 0.14 0.17 0.10 1.02 0.08 0.09 0.55 1 .29 0.68 1.23 0.35 1 .11 0.31 0 .23 0.57 0.62 0.43 Included Sapwood C Radial Tangential Longitudinal All (control) A v e r a g e 0.09 0.15 0.05 0.07 0.59 0.95 0.76 1 . 2 9 0.37 0.62 0.22 1.65 0.15 1.30 1.28 2.55 0.98 2.14 0.66 1.91 0.53 0.39 1.34 1 .29 0.89 Included Sapwood B Radial Tangential Longitudinal All (control) A v e r a g e 0 .06 0.17 0.07 0.17 0 .52 0.96 0 . 6 1 1.02 0 .32 0.58 0.21 1.22 0 .16 1.39 0.93 2.00 1 .03 2.21 0.58 1.71 0 .42 0.45 1.10 1.22 0.80 True Heartwood (inner) A Radial Tangential Longitudinal All (control) A v e r a g e 0.05 0.05 0.04 0.07 0.28 0.36 0.31 0.50 0.17 0 .25 0.12 0 .92 0.09 1 .27 0.61 1.64 0.75 1.68 0.39 1.38 0.29 0.37 0.72 0.81 0.55 AVERAGE: 0.43 0.67 1.12 1.98 1.05 The effect of direction of penetration on creosote retentions in mountain-type Douglas fir wood at 70°F. treating temperature and at atmospheric pressure. f 17777 / \ MM till'//// L E G E N D ; R a d i a l . T a n g e n t i a l . In al l d i r e c t i o n s . L o n g i t u d i n a l . f~| A v e r a g e . Hea r twood I nc luded sapwood Included sapwood Heartwood D C B A Po s i t i on in the c r o s s sect ion. -28- Sutherland (50) attributes the improved absorption at high pressures to an enlargement of the pores in the pit membrane. 2 . Influence of temperature on creosote retention An average retention of 1 . 3 8 grams was obtained for 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 in a retention increase of 254 percent i n heart- (B) wood, 195 percent i n included sapwood/ and only 4 percent in sapwood (Table 3 ) . This indicates that temperature had the greatest influence on heartwood, less on included sapwood, and least on sapwood. The above order i s different at atmospheric pressure. Temper- ature appears to have very l i t t l e influence on creosote retention of heartwood. It may be concluded, therefore, t h a t the application of high temperature, without elevated pressure, does not have a significant influence on creosote retention. In other words, in treating heartwood, the application of both high pressure and temperature i s essential. In sapwood, approximately the same retentions were obtained at 70°F. and atmospheric pressure as i n heartwood at 212°F. and 100 psi pressure. This clearly 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 pressure. The reverse i s true of sapwood. Here temperature has a greater influence on retention at atmospheric pressure than at 1 0 0 p s i pressure (Figure 8 ) . The effect of temperature on the absorption of creosote can be explained by a change in viscosity of creosote with a change in temperature. Creosote has higher viscosity at 70°F., but becomes increasingly thinner and - 2 9 - TABLE 3 . Effect of pressure and temperature on creosote retention in mountain-type Douglas f i r . Increase i n Creosote Retention - Percent Kind of Wood Pressure Increase from Atmospheric to 100 psi at: Temperature Increase from 70°F. to 212°F. at: 70°F.. 212°F. Atmospheric Pressure 100 psi Sapwood (S) 216* 115 52 4 Heartwood (D) 150 553 2 1 217 Included Sapwood (C) 78 208 6 8 1 8 9 Included Sapwood (B) 81 195 81 195 Heartwood (A) 1 2 9 452 4 7 254 AVERAGE: 131 3 0 5 54 1 7 2 *Increase i n retention = 1 0 0 R70°F., 15 p s i L = 100 3 .6? - i ~ = 216% R 7 0 P., 1 0 0 psi = average retention value of 1 6 test specimens at 70°F. treating temperature and 1 0 0 p s i . Average ;R values were taken from Table 2 , 4.0 i c o % 2.0. 1.5 1.0 -x Hxh x X X X X X F i g . 6 < x k/ IX E f f e c t of p r e s s u r e a n d t e m p e r a t u r e on c r e o s o t e r e t e n t i o n i n a m o u n t a i n - t y p e D o u g l a s f i r s t e m . LEGEND: (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. 2l2°F.temp., 100 psi. pre ssure. | | Average. i O I X X 1 X Sapwood S Heartwood D Included Sapwood C Included Sapwood B Heartwood A P o s i t i on in the c r o s s s e c t i on . £ o I F i g . 7 . T b e i n f l u e n c e o f p r e s s u r e a n d t e m p e r a t u r e o n c r e o s o t e r e t e n t i o n in a m o u n t a i n - t y p e D o u g l a s f i r s t e m . c « <p or 4.C S a p w o o d ( S ) 3.0 I 2.0 1.0 8z Inc luded Included sapwood (C) sapwood (B) Hear twood (A) Heartwood (D) 7 0 I 5 212 15 70 100 212 Temperature - 4 F . 100 P r e s s u r e - p s i . F i g . 8 . I n f l u e n c e o f p r e s s u r e a n d t e m p e r a t u r e on c r e o s o t e r e t e n t i o n i n m o u n t a i n - t y p e D o u g l a s f i r s a p w o o d a n d h e a r t w o o d . L E G E N D : 1 ' r 70 212 Atmospheric lOOps Temperature -°F. Pressure. -33- more fl u i d at higher temperatures. Consequently, i t penetrates wood more readily at higher than at lower temperatures. A definite relationship between viscosity and penetrance, which could be expressed by empirical equations for specific conditions, was found by Bateman (4). A great importance is attributed by Howald (28) to the presence of peptized colloids in o i l preservatives. The colloids are believed to exert their influence by changing the capillary relationship between o i l and wood. Raphael and Graham (42) confirmed Bateman*s conclusion, stating that o i l s with low viscosity and specific gravity are the best penetrants. High-viscosity, low-specific gravity o i l s penetrate better than high-viscosity and high-specific gravity o i l s . It was concluded by Liese (32) that, although the depth of pene- tration of o i l y wood preservatives i s influenced by their viscosity, surface tension, and specific gravity, even greater importance must be ascribed to chemical factors, such as the chemical composition of preservative. 3. Correlation between specific gravity and permeability The average specific gravity of the five zones remained f a i r l y constant (Table 4 and Figure 9D), while the permeability of the corresponding zones varied significantly. Consequently, there was no definite correlation between specific gravity and ease of penetration. Miller (37) recently investigated the influence of specific gravity on the penetrability of Douglas f i r , but found no correlation between the two variables. In their absorption studies of ponderosa pine with oil-base preservatives, Brown, Moore, and Zabel (8) concluded that an increase in 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 s~«->^cross section Heartwood A Included Sapwood B Included Sapwood C Heartwood D Sapwood S Properties 1 2 3 4 5 Specific gravity . 3 9 5 . 4 0 3 . 3 9 2 . 4 0 0 . 3 7 6 Percent summerwood 23 25 26 22 25 Growth rate (rings per in oh) 18 .1 2 2 . 0 28.5 6 0 . 2 6 3 . 8 Fibre length (mm.) 3 . 0 3 3 . 4 8 4 . 1 5 4 . 1 1 4.14 Number of longitudinal resin ducts per sq. i n . 316 9 0 3 2 5 226 632 Alcohol-benzene-soluble extractives (%) 4 . 6 6 1 . 2 1 2 . 6 8 7 . 0 1 2 . 2 7 Acetone-soluble extractive content (%) 3 . 3 4 1 . 1 3 2 . 4 0 6 . 1 0 1 . 8 3 Ether-soluble extractive content (%) 3 . 1 7 1 . 8 7 1 . 5 7 6 . 1 4 1 . 9 0 Creosote retention g/cm3 0 . 0 6 5 0 . 0 9 4 0 . 1 0 5 0 . 0 5 1 . 3 0 4 -35- Fig.9. Creosote retentions and some physical and chemical properties of a mountaii type Douglas fir stem at five positions A . Creosote r e t en t ion , in the cross section. G. Number A Heartwood B C Included sapwood Incl. sapwood 0 Heartwood E Sapwood Pith P o s i t i o n in the cross section. Bark . - 3 6 - specific gravity of wood causes a slight decrease in absorption. This effect decreases with an increase in moisture content. 4. Influence of percent summerwood on permeability There appears to be a linear correlation between percent sunmer- wood and permeability (Table 4 and Figure 9C). The apparent relationship, however, can not be accepted as being significant, for the following reasons: (i) The average percent summerwood values of the five zones vary only from 22 to 2 6 percent. This 4 percent variation between the five zones i s smaller than the 7.4 percent standard deviation of the entire data. ( i i ) The accuracy of the method used to determine percent summerwood was approximately + 3 percent. ( i i i ) An analysis of variance revealed no significant differences between the percent summerwood values of the different zones. Specimens representing a much wider range of percent summerwood must be selected to investigate the influence of this factor on treat a b i l i t y . The effect of percent summerwood on penetration of preservatives into Douglas f i r was investigated by Miller ( 3 7 ) , who found no correlation between the two variables. 5. Effect of growth rate on creosote retention No significant correlation between growth rate and the ease of penetration i s revealed i n Figure 9B and Table 4. The growth rate decreases from pith to bark, but the creosote retention values do not follow the same pattern. Other factors seem to be of more importance in the determination of wood permeability. Neither Bryan (9) nor Mil l e r ( 3 7 ) found any relationship between growth rate and treatability of wood when impregnating Douglas f i r with -37- creosote. In their investigation of longitudinal penetration of creosote in Douglas f i r , Raphael and Graham (42) concluded that wood with high ring count showed a more uniform distribution of preservatives than wood with a low ring count. 6. Relationship between fibre length and creosote retention In longitudinal penetration, the preservative must pass through fewer c e l l walls in woods with long fibres than in woods with short fibres per unit length. Theoretically, a deeper penetration and a higher retention would be expected in the f i r s t type of wood than in the second. The results of this study, given in Table 4 and Figure 9, indicate that fibre length i s not an important factor in the determination of the permeability of wood. Any minor influence which fibre length may have is dominated by the effect of more important factors. 7. Influence of longitudinal resin ducts on penetrability (Table 4 and Fig. 96) Within this mountain-type Douglas f i r stem no correlation was found between the number of longitudinal resin ducts and longitudinal penetration. It was observed, however, that resin ducts in heartwood contained more resin than those i n included sapwood. Consequently, the resin ducts in included sapwood may have aided penetration, whereas those i n the heartwood are less l i k e l y to have done so. Hunt and Garratt (29) stated that i n mountain-type Douglas f i r heartwood resin ducts may be penetrated to a greater or lesser extent, but so l i t t l e preservative enters the adjacent wood cells that the resultant penetration i s l i t t l e improved. On the other hand, maximum penetration along the resin ducts of Douglas f i r was observed by Scarth (43), who attributed great significance to this factor. -38- 8. Correlation between extractive content and treatability an There appears to be^inverse relationship between alcohol-benzene- soluble extractives and creosote retention in Douglas f i r heartwood (See Figure 10). An increase in alcohol-benzene solubles results in a propor- tional decrease in wood permeability. Thus, heartwood having a high extrac- tive content is more d i f f i c u l t to impregnate with creosote than wood rela- t i v e l y low i n extractive content. This correlation between the two variables did not prove to be s t a t i s t i c a l l y significant. A similar relationship was obtained between acetone-soluble extrac- tives and creosote retention. The slope of the straight l i n e , shown in Figure 12, does not significantly d i f f e r from zero. The results were somewhat different with ether-soluble extractives. A hyperbolic, rather than a straight-line, relationship can be observed in Figure 11. The curve indicates that the influence of extractive content on wood permeability decreases with increasing extractive content. Thus, i t may be assumed that only a small quantity of extractives i s required to cause major changes in the treatability of wood. This small amount of extractives in the c e l l wall 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 capillaries and the permanent pores in the pit membrane. Included sapwood contained a similar amount of extractives to true sapwood, and approximately one-third of that of the heartwood (Table 4). Creosote retention of included sapwood was only one-third of that of the sapwood and not quite twice as much as that of the heartwood. The amount of extractives, as well as their location within the cell-wall structure, must be considered when studying their effect on wood permeability. Based on the fact that sapwood and included sapwood contained similar amounts of extractives but possessed different permeability character- o Sapwood F i g . 10. u o CO E 2.25 c o c <u - .20 a> or C o r r e l a t i o n b e t w e e n c r e o s o t e r e t e n t i o n a n d a l c o h o l - b e n z e n e s o l u b l e s o f m o u n t a i n - type D o u g l a s f i r h e a r t w o o d . .15 Y=0.114-0.009x S E E =0.0155 r = .85 vO i .10 .05 6 7 Alcohol - benzene solubles % Relationship between c r e o s o t e retention and ether solubles of a mountain-type Douglas f i r heartwood. -40- i s t i c s , i t may be assumed that the locations of the extractives are not the same in the two types of wood. This assumption is confirmed by the fact that the major function of sapwood in the l i v i n g tree i s conduction, while that of the included sapwood i s mechanical support. It i s probable that the extrac- tives in both the included sapwood and heartwood are located in such a way as to p a r t i a l l y or f u l l y seal most of the capillaries present in the c e l l walls. The difference between included sapwood and normal heartwood, as far as permeability i s concerned, may be due to the extent to which the c e l l wall capillaries are blocked with extractives. In included sapwood the degree of deposition of extractives in the c e l l wall capillaries i s expected to be lower than i n the heartwood. This would be expected since the former tissue has apparently only p a r t i a l l y undergone the process of conversion from sapwood to a heartwood. In addition, included sapwood contains^smaller percentage of extractives available for deposition than heartwood. This theory may be supported by the fact that creosote retention i n heartwood was approximately half of that in included sapwood. Stone (49) found spaces between the t o r i and the edges of the pit aperture, when analysing photomicrographs of aspirated pits at high magnifi- cations. From this finding he concluded that the surface of the torus was too rough to completely seal the aperture to the flow of most liquids. There i s a possibility that these openings did not exist in the original wood, but were caused during the preparation of the slides by the removal of some of the extractives which might normally plug the openings. 9. Improvement in treatability due to extraction In the previous part of this study an inverse relationship was found to exist between extractive content and permeability. I f this correlation i s o —r- R e t e n t i o n - g r a m s / cc 8 ro ro N> CD • S * • 3 o o < CD 3 CD a 0) on en > o CO o m (A O -N) c C T CO CD Ol m " m o II • o = 2 * cn • p o o ao Q O CO O CD Q O o X C L -•» CD 3 o o mmm9 « I CD a * O CD CD © O o CD O > 3 S 8 c a cF - 4 2 - true, an improvement i n r e t e n t i o n may be expected upon the removal of some o f the e x t r a c t i v e s from the c e l l w all structure. The r e s u l t s given i n Table 5 support t h i s assumption. Improved permeability was obtained following e x t r a c t i o n . The extent of the improvement i n permeability v a r i e d i n the d i f f e r e n t types of wood. The average r a t i o s between the creosote retentions of extracted and unextracted t e s t specimens were 1 . 2 f o r sapwood (S), 6 . 5 f o r included sapwood (C), and 8 . 1 f o r heartwood ^D) (Table 5 ) . From the above f i g u r e s , and from Table 4 , i t may be observed that heartwood, having the highest e x t r a c t i v e content, on extraction improved i n permeability to the greatest extent. Sapwood, containing low percentages of 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 s l i g h t l y . Included sapwood, with s i m i l a r e xtractive contents to that of sapwood, improved greatly in perme- a b i l i t y . Since the improvement i n the permeability of sapwood and included 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 s i m i l a r e x t r a c t i v e contents, e i t h e r the l o c a t i o n or types of e x t r a c t i v e s or the degree of a s p i r a t i o n of the bordered p i t s must.differ i n the two kinds of wood. This observation supports the previous assumption which a t t r i b u t e s a great s i g n i f i c a n c e to the l o c a t i o n of extractives i n the c e l l w all s t r u c t u r e . Heartwood, having the highest e x t r a c t i v e content, as well as the greatest 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 f a c t that the amount of e x t r a c t i v e present i n wood i s another major f a c t o r i n deter- mining i t s permeability. 'The data reveal no major dif f e r e n c e s between the hot and Soxhlet extraction methods. Therefore the temperature of the solvent appeared t o have no measureable influence on the degree of improvement i n permeability. This i s probably due to the long e x t r a c t i o n period employed. Of solvents used TABLE 5 . Average creosote retentions of mountain-type Douglas f i r heartwood, Included sapwood, and sapwood, following a 240-hour extraction in different solvents. Duration of Extraction Type of Solvents Kind of wood: Included Sapwood C Heartwood D Average (Hours) Soxhlet Extraction method: Hot | Soxhlet Hot 6 0 6 0 6 0 6 0 Alcohol-benzene ) Ether ) Acetone ) Water ) 0 . 6 7 (Retention - 0 . 6 6 - grams) 0 . 4 6 0 . 5 6 0 . 5 8 2 2 0 1 0 1 0 Alcohol-benzene ) Alcohol ) Water ) 0 . 6 9 0 . 5 3 0 . 5 6 0 . 4 5 0 . 5 5 2 3 0 1 0 Sodium hydroxide ) Water ) 0 . 6 7 0 . 6 8 0 . 5 7 0 . 6 6 0 . 6 4 2 4 0 Water 0 . 6 5 0 . 6 7 0 . 6 7 0 . 6 2 0 . 6 5 None Control (No extraction) 0 . 1 0 0 . 1 0 0 . 0 7 0 . 0 7 0.08 A v e r a g e: 0 . 5 5 0 . 5 3 0 . 4 6 0 . 4 7 A v e r a g e: 0 . 5 4 0 . 4 7 Ratio of retention of extracted specimens to unextracted: Average ratio: 6 . 7 6 . 5 6 . 3 8 . 6 8 . 1 8 . 2 Water extraction, 240 hrs.; Average retention, extracted = 0 . 4 8 g.; unextracted, 0 . 3 9 g.; Ratio = 1 . 2 -44- in the extraction studies, water gave most improvement i n permeability (Table 5). The reason for this may be that the water relieved, p a r t i a l l y or f u l l y , the aspiration in the bordered p i t s , thus providing a greater number of channels for liquid movement. This i s , of course, only an hypothesis which could be proved or disproved by a detailed study of the degree of aspiration in extracted and unextracted matched specimens. This aspect of the study may have some practical significance in the wood preserving and pulp industries. A method of pre-treatment could be developed to improve the permeability of wood. According to the results obtained in this investigation, water would appear to be the most effective, and the most economical solvent for extraction. A problem in the wood preserving industry would originate from the large sizes of the material to be extracted, and the long periods of time required for solvent to reach the middle portions of what i s a relatively impermeable material. Furthermore, the use of higher temperatures may be necessary to increase the effectiveness of the solvent. The pulp industry, however, would not face this problem as the size of the chips i s sufficiently small to enable thorough extraction in a relatively short time, 10. Effect of solvent on wood Water, at low temperatures, does not react chemically with wood. Its action i s confined to the removal of some of the water-soluble extractive content. At elevated temperatures, water has a marked chemical effect on wood. It influences strength properties by breaking down some of the pentosan and cellulose components. The amount of these materials removed from the wood depends on the severity of the conditions (temperature, pressure and duration of treatment). - 4 5 - Neutral solvents, such as alcohol, benzene and acetone, do not affect the strength properties of wood. These solvents, having larger molecular sizes than water, cannot enter the small capillaries in the amorphous region, and therefore do not rupture the secondary valence forces between the cellulose molecules. Sodium hydroxide reacts with l i g n i n and wood carbohydrates, breaking down the basic components and causing delignification. The degree of delignification depends on the concentration of the solvent and on the treating conditions. In the extraction of Douglas f i r wood with 0.1 percent sodium hydroxide, i t was observed from the reddish color of the solution, and the appearance of the extracted specimens, that a large portion of the li g n i n had been removed. The amount of lig n i n removed from the test specimens was not determined. 11. Bordered pi t aspiration Most of the t o r i i n the bordered pits of sapwood, heartwood, and included sapwood appeared to be in an aspirated condition when observed in 20-micron-thick sections under a binocular microscope. The magnification used was approximately 6 0 0 X. .'These observations may not be reliable for two reasons. One of these i s that much thinner sections, 2 microns in thickness, are required for the accurate investigation of the degree of aspiration. Another reason could be the possible effect of sectioning and slide preparation on the degree of aspiration observed. The latter cause of error probably exists in many of the studies of this type. Observation of p i t aspirations have usually been made on wood sections cut on a microtome. The disruption of the wood structure during sectioning and slide preparation should not be overlooked as a possible source of error due to mechanical forces and chemical solvents. -46- I f the uniform aspiration of the bordered pits observed in heartwood, sapwood, and included sapwood i s accepted as valid, i t leads to an important conclusion. This is that the aspiration of bordered pits has no effect on the permeability of mountain-type Douglas f i r . 12. Direction of penetration (Figure 5) Much better penetration was obtained from the ends than from the sides of the test specimens. In fact, in many specimens, complete impreg- nation of the material was obtained when only the end grain was exposed to the creosote. The ratios between longitudinal and side penetration of the included sapwood ( B , C ) were higher than those for 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 ratios (Figure 5), however, were considerably smaller than those given by Maclean (35). He reported that i n the very refractory, Rocky Mountain-type Douglas f i r , the longitudinal 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 fact that the specimens used in the present study were too short to obtain a true measure of longitudinal penetration, and thus of the ratio of longitudinal to side penetration. In the four zones ( A , C , D , S ) of this mountain-type Douglas f i r stem the radial penetration was superior to the tangential penetration (Figure 5). In order to find an explanation for this, an intensive anatomical study would be required. It may be assumed, however, that the rays and/or the radial resin ducts f a c i l i t a t e d the radial penetration (from the flat-sawn face) of creosote. No count was made of the number of fusiform rays, nor a study of their condition. -47- SUMMARY ' 1. Permeability of included sapwood is superior to that of normal heartwood, •i but inferior to true sapwood. 2. The effect of pressure on creosote retention at 212°F. is greatest for heartwood, less for included sapwood, and least for sapwood. The influence of pressure on creosote absorption in heartwood is greater at higher temperatures than at lower ones. Pressure has a greater effect on the retention of sapwood at lower temperatures than at higher ones. 3. The influence of temperature on creosote retention in Douglas f i r heart- wood i s greater at 100 p s i pressure than at atmospheric pressure. The reverse is true for sapwood. Temperature has a greater influence on retention at atmospheric pressure than at 100 p s i pressure. 4. There was no definite correlation between specific gravity of wood and ease of penetration. 5. Percent summerwood did not vary significantly within this 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 factor in the determination of wood permeability. 8. No relationship was found between the number of longitudinal resin ducts and longitudinal penetration of creosote, probably due to lack of length of specimens, as noted. -48- 9. (i) A s t a t i s t i c a l l y non-significant correlation was obtained between alcohol-benzene-soluble extractives and creosote retention. ( i i ) The slope of the straight line obtained for acetone-soluble extractives and creosote retention did not significantly d i f f e r from zero. ( i i i ) A hyperbolic, rather than a straight-line, relationship was found between ether-soluble extractives and creosote retention. The higher the extractive content, the greater the retention. (iv) Within this mountain-type Douglas f i r stem the amount as well as the location of the extractives i s considered to be important in the determination of wood permeability. 10. Pre-treatment of samples with different solvents in order to remove some of the extractives improved the permeability of heartwood, included sapwood and sapwood. The increases were respectively 8.1, 6.5 ( a l l solvents), and 1.2 (only water) times, compared with the controls. 11. No definite conclusion can be drawn from the limited number of obser- vations on the degree of bordered p i t aspiration. 12. It would be desirable to know the effect of extraction treatment on the c e l l walls and on the mechanical properties of the wood. A chemical analysis of the solvents after the extraction treatment would show which wood components had been extracted. 13. The development of an extraction pre-treating technique i s suggested for the wood preserving and pulp industries, to improve wood permeability. Type of solvent, temperature, duration of treatment, and economics should be determined for specific conditions. -49- The specimens used in the present study were too short to provide a true measure of the ratio of longitudinal to side penetration. In the four zones of the log section^ higher retentions were obtained in the specimens when exposing the tangential faces than the radial faces. -50- R E F E R E N C E S 1. American Society for Testing Materials. 1959. ASTM Standards on wood, wood preservatives, and related materials. ASTM Committee D-7. Philadelphia. 2. Bailey, I.W. 1913. The preservative treatment of wood. I and II. Forestry Quart. 11: 12-20. 3. . 1957. The structure of the pit membranes in the tracheids of conifers. Holz als Roh und Werkstoff. 15(£): 210-213. Commonwealth Scientific and Industrial Research Organization, Trans. No. 3639. 4. Bateman, E. 1920. Relation between viscosity and penetrance of creosote into wood. Chem. Met. Eng. 22: 359-360. 5. Belford, D.S. I960. Some application of physical methods in the study of preservative treated wood. Fifth World Forestry Congress. Seattle, Washington. 6. Blew, T.O. 1955. Study of the preservative treatment of lumber. U.S. Dept. of 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. Vol. 1. McGraw-Hill Book Co. Inc., New York, 651 pp. 8. Brown, F.L. and R.A. Moore, R.A. Zabel. 1956. Absorption and pene- tration of oil-soluble wood preservatives applied by dip treatment. State Univ. of New York, College of Forestry in Syracuse. 38 pp. 9. Bryan, T. 1930. Preliminary report on the creosoting of Douglas f i r sleepers. Dept. Sci. 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 of certain factors influencing the movement of liquids in wood. Jour. Phys. Chem. 39: 103-120. 11. Buckman, S.T. 1936. Creosote distribution in treated wood. Ind. Eng. Chem. 28: 474-480. 12. Buro, A. and E.A. Buro. 1959. Beitrag zur Kenntnis der Eindringwege fur Flussigkeiten in Kiefernholz, Holzforschung, 13 (8): 71-77. 13. Burr, A.K. and A.J. Stamm. 1947. Diffusion in wood. Jour, of Phys. Chem. 51 ( l ) : 240-261. 14. Cochran, W.G. and G.M. Cox. 1950. Experimental Designs. John Wiley and Sons, New York. pp. 611. -51- 15. CSte, W.A. and W. Liese. 1958. Electron microscope studies of p i t membrane structure. 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. 1925. An Introduction to Plant Anatomy. McGraw-Hill Book Co., Inc., New York. p. 2"6-35. 18. Erickson, H.D., H. Schmitz, and Gortner, R.A. 1937. The permeability of woods to liquids and factors affecting the rate of flow. Univ. Minn. Agr. Exp. Stat. Tech. B u l l . 122. 42 pp. 19. Fleischer, H.O. 1953. An anatomical comparison of refractory and easily 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 inter- f a c i a l tension of creosote against water. Physics 6: 174-177. 21. Gerry, E. 1913. Microscopic structure of woods in relation to _̂ properties and uses. Proc. of Soc. Amer. For. 8(2): 159-157. :' 22. Graff, J.R. and R.W. Miller. 1939. Fiber dimensions. Paper Trade Jour. 109(8): 31-37. 23. Graham, H.M., and E.F. Kurth. 1949. Constituents of extractives from Douglas f i r . Ind. and Eng. Chem. 41: 409-414. 24. Greaves, C. 1951. Preservative treatment of 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 pits in Douglas f i r : A study of the position of the torus in mountain and lowland specimens in relation to creosote penetration. Jour. For. 17(2) : 813-833. 26. 1924. Further note on the position of the t o r i in bordered pits in relation to penetration of preservatives. Jour. For. 22(6): 82-88. 27. Harkom, T.F. 1959. L i f e of creosoted wooden pilings when used for building foundations to support masonry footlings. For. Prod. Lab. of Can., Ottawa. 10 pp. 28. Howald, A.M. 1927. Penetrance of o i l y fluids i n wood. Chem. Met. Eng. 34: 353-355 and 413-415. 29. Hunt, G.M. and G.A. Garratt. 1953. Wood Preservation. 2nd edition. McGraw-Hill Book Co. Inc., New York. 417 pp. 30. Kennedy, R.W. and J.W. Wilson. 1956. Variation in t a x i f o l i n content of a Douglas f i r stem exhibiting target ring. For. Prod. Jour. 6(6): 230-231. -52- 31. Koljo, B. 1954. Influence of the methods of impregnation on the absorption of preservatives in wood impregnation. Holz als Roh-und Werkstoff. 12(1): 7-16. 32. Liese, W. 1951. I he influence of the physical properties of o i l y preservatives on their penetration into wood. Bitumen, Teere, Asphalte, Peche und Verwandte Stoffe. 2(11): 276-279. 33. • 1954. Fine structure of bordered pits i n conifer wood. Commonwealth Sci. Ind. Res. Org. Translation No. 3621. 34. > and W.A. Cote-. i960. Electron microscopy of wood. Fifth World Forestry Congress. Seattle, Washington. 6 pp. 35. Maclean, J.D. 1952. Preservative treatment of wood by pressure methods. U.S. Dept. of Agric., Washington, D.C. Publication No. 224. 160 pp. 36. Marts, R.O. 1955. Some structural details 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 of pit membrane in coniferous woods with special reference to preservative treatment. Forestry 6(1): 109-120. 39. Preston, R.D. 1959. The fine structure of wood with reference to impregnation. 1. Timb. Techn. 67(2245): 458-464. 40. . 1959. The fine structure of wood with reference to impregnation.-2. Timb. Techn. 67(2246): 502-508. 41. Proctor, P.B. and J.W.B. Wagg. 1947. The identification of refractory Douglas f i r by means of growth characteristics. Proc. Am. Wood Pres. Assoc. 43= 170-175. 42. Raphael, H.T. and R.D. Graham. 1951. The longitudinal penetration of petroleum o i l s i n Douglas f i r heartwood after a fifteen minute immersion. Proc. Am. Wood Pres. Assoc. 47: 173-175. 43. Scarth, G.W. 1928. The structure of wood and i t s penetrability. Paper Trade Jour. 86(17): 53-58. 44. — and J.D. Spier. 1929. Studies of the c e l l walls in wood. 11. Effect of various solvents upon permeability of red spruce heartwood. Trans. Roy. Soc. Can. 23: 281-288. 45. Smith, D.M. 1955. Comparison of methods of estimating summerwood percentage in 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. -53- 47. Stamm, A.J. 1929. The capillary structure of softwoods. Jour. of Agric. Res. 38(1): 23-67. 48. . 1946. Passage of liquids, 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 pits of Douglas f i r with reference to the permeability of wood to liquids. Masters thesis. University of Washington. 41 pp. 50. Sutherland, J.W. 1932. Forced penetration of liquids into wood and i t s relation 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 affects penetration by preservatives. Am. Ry. Eng. and Maint. of Way Ass. Bull. 107.10. 1. 638-653. 52. Weiss, H.F. 1912. Structure of commercial woods in relation to the injection of preservatives. Proc. Am. Wood Pres. Assoc. 8: 158-187. 53. Wise, L.E. and E.G. Jahn. 1952. Wood Chemistry. 2nd ed. Vol. I and II. Reinhold Publishing Corp., New York. 595 pp. APPENDIX - 5 4 - TABLE 6 . Creosote absorption values of mountain-type Douglas f i r sapwood. Time Absorption (Hours) (Grams) 0 0 1 minute 0 . 0 7 0 . 2 5 0 . 3 0 0 . 5 0 0 . 3 8 1 . 2 5 0 . 5 0 2 0 . 5 6 3 0 . 6 2 4 0 . 6 6 5 0 . 6 9 6 0 . 7 1 7 0 . 7 3 8 0 . 7 5 TABLE 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. P o s i t i o n i n the Cross Section F i g . l D i r e c t i o n of Penetration Atmospheric pressure 70° 1 2 3 4 212°F. Pressure at 100 p s i 70°F. Replicates 2 3 4 11 2 212°F. 1 3 3 4 True Sapwood True Heartwood D Included Sapwood Included Sapwood B True Heartwood Radial Tangential Longitudinal A l l (Control) Radial Tangential Longitudinal A l l (Control) R a d i a l Tangential Longitudinal A l l (Control) Radial Tangential . Longitudinal A l l (Control) Radial Tangential Longitudinal A l l (Control) 0 . 3 6 0 . 5 8 0 . 3 3 0 . 6 8 0 . 4 3 0 . 3 0 0 . 3 8 0 . 1 4 1 . 3 8 1 . 3 7 1 . 8 8 1.90 2 . 0 1 2.15 2 . 1 4 2 . 3 6 0 . 0 2 0 . 0 3 0 . 0 9 0 . 0 7 0 . 0 2 0 . 0 3 0 . 0 4 0 . 0 3 0 . 2 1 0 . 2 3 0 . 2 1 0 . 2 0 0 . 2 6 0 . 2 9 0 . 2 7 0.31 0 . 0 9 0 . 1 2 0 . 0 7 0 . 1 1 0 . 0 7 0 . 0 5 0 . 0 1 0.08 0 . 5 6 0 . 6 4 0 . 6 5 0 . 5 2 0.81 0 . 7 7 0 . 7 4 0 . 7 1 0 . 0 2 0 . 0 5 0.08 0 . 0 7 0 . 0 7 0 . 0 5 0.08 0.08 0 . 5 6 0 . 5 6 0 . 4 9 0 . 4 5 0 . 6 0 0 . 6 8 0 . 5 8 0 . 5 7 0 . 0 3 0 . 0 3 0.08 0 . 0 5 0 . 0 1 0 . 0 1 0 . 0 6 0 . 0 6 0 . 2 7 0.30 0 . 2 7 0 . 2 7 0 . 2 9 0 . 3 2 0 . 3 5 0.26 Retention values (grams) 1.88 1.57 1 . 3 7 1.18 0.52 0.66 1.12 0.88 2.01 2.01 2 . 0 6 2.08 2.49 3.74 2.24 2.13 0 . 0 5 0.15 0.05 0.08 0 . 0 4 0.06 0.09 0.10 0.17 0 . 2 5 0 . 2 5 0 . 2 9 0 . 3 0 0 . 3 0 0 . 2 3 0 . 2 9 0.14 0.20 0.15 0.12 0.02 0.07 0.09 0.09 1.06 0.89 0.86 0.98 1.35 1 . 4 6 1 . 2 5 1.10 0'.1'4 0.15 0.17 0.21 0.25 0.17 0.11 0.13 1.02 0.90 0 . 9 7 0.93 1.10 1.10 1.C0 0.86 0.04 0.04 0 . 0 7 0 . 0 4 0.06 0.02 0.08 0.10 0.35 0 . 4 4 0.35 0.31 0.45 0.47 0.49 0.59 2 . 5 0 - 2 . 8 5 1 . 7 2 1 . 3 7 4 . 2 6 3 . 6 6 4 . 4 6 4 . 2 1 4 . 2 2 4.13 4 . 0 9 4 . 1 2 4 . 1 4 4 . 2 2 4 . 2 9 3 . 7 0 0 . 0 2 0 . 0 2 0 . 1 7 0 . 2 0 0 . 0 3 0 . 0 2 0 . 0 7 0 . 2 0 0 . 5 4 0 . 4 8 0 . 5 6 0 . 6 1 0 . 6 4 0 . 5 8 0 . 7 4 0 . 7 6 0 . 3 9 0 . 1 1 0 . 1 9 0.18 0 . 2 5 0 . 1 4 0 . 1 0 0 . 1 1 1 . 3 2 1 . 3 0 1 . 3 0 1 . 2 1 1 . 1 0 0 . 9 0 1 . 0 5 0 . 8 8 0 . 1 2 0 . 2 0 0 . 2 9 0 . 2 4 0 . 1 0 0.18 0 . 2 0 0.15 1 . 0 0 0 . 9 3 0 . 8 6 0 . 9 2 1 . 1 9 0 . 8 6 1 . 0 0 1 . 0 7 0 . 1 7 0 . 1 1 0 . 1 2 0.08 0 . 0 5 0 . 0 5 0.13 0 . 1 3 0 . 6 2 0 . 5 9 0 . 6 2 0.62 0 . 7 2 0 . 6 5 0 . 9 2 0 . 7 1 3.58 3 . 5 2 2.99 3.34 4 . 2 9 4.30 3.69 3.31 4 . 0 9 4 . 0 6 3 . 4 2 3.70 4.23 4 . 2 7 3.54 3.90 0.75 0.78 1 . 2 9 1.25 0.87 0.74 0.98 1.21 1.17 1.28 1 . 3 2 1.40 1.04 1.12 1 . 4 2 1.32 1.78 2.01 1.41 1 . 4 0 0 . 7 0 0.98 1.95 1.56 2.75 2 . 5 2 2.29 2.63 1.96 2 . 2 5 2.26 2.08 0 . 7 2 1.05 1.73 1.36 1.10 1.20 1.82 1 . 4 2 2.05 2.07 2.20 1.59 2.11 2.10 2.40 2.22 1.15 0.48 0.46 1.58 0 . 7 2 1.07 1.80 1.49 1.20 1.73 1.87 1.75 1.55 1.75 1.82 1.61 -56- TABLE 8. Analyses of variance of creosote retentions in mountain-type Douglas f i r as affected by pressures, temperatures, position, and direction of penetration. Source Sum of Mean Squares D.f. Squares F 1. Pressure 79.65 1 79.65 1632** 2. Temperature 23.87 1 23.87 489** 3. Position 193.48 4 48.37 ooi** 4. Direction 35.70 3 11.90 244** 5. Pressure x temp. 7.48 1 7.48 153.3** 6. Pressure x position 31.46 4 7.86 161.1** 7. Pressure x direction 1.68 3 0.56 11.5** 8. Temp, x position 1.81 4 0.45 9.2** 9. Temp, x direction 0.37 3 0.12 2.5 n 10. Position x direction 7.31 12 0.61 12.5** 11. Pressure x temp, x position 5.82 4 1.45 30.0** 12. Pressure x temp, x direction 0.55 3 0.18 3.7* 13. Pressure x position x direction 0,30 12 0.69 14.1** 14. Temp, x position x direction 3.24 12 0.27 5.5** Error 12.35 253 0.048814 TOTAL1 413.07 C 351.77 n.s. = non-significant *significant **highly significant -57- TABLE 9. Specific gravity values* of a mountain-type Douglas f i r stem. Replicates Position in Cross Section 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 AVERAGE: 0.395 0.403 0.392 0.400 0.376 *Based on green volume, oven-dry weight of unextracted specimens. -58- TABLE 10. Percent summerwood values of a mountain-type Douglas f i r stem and analyses of variance. \ Position Ring ^ \ Heartwood Included Included Heartwood Sapwood Sapwood Sapwood number A B C D S 1 26 19 29 20 25 22 25 15 2 2 7 30 29 27 25 29 25 33 3 28 20 25 3 2 37 25 33 25 4 29 27 30 22 17 25 17 25 5 30 2 4 30 3 2 17 33 25 50 6 31 29 21 33 20 33 33 9 7 3 2 26 23 38 11 14 40 10 8 33 22 33 27 30 15 33 22 9 34 17 22 25 15 25 25 29 10 35 15 23 20 18 20 25 17 11 36 21 18 15 25 25 20 26 12 37 31 25 20 25 20 20 20 13 38 17 21 20 7 29 33 25 14 39 23 14 14 2 5 33 25 15 40 27 30 14 14 20 17 16 41 25 20 20 33 25 17 4 2 21 25 2 5 2 5 25 18 43 30 13 17 33 18 19 44 31 14 17 33 11 20 45 33 3 0 33 33 22 21 46 38 14 12 17 12 22 47 22 23 33 33 23 48 13 8 33 2 4 49 20 21 29 25 50 30 2 9 Sums 298 739 553 1012 1228 Sum of squares 7172 9827 15,529 24,108 34,180 Averages 22.9 25.3 26.3 21.5 25.1 Standard deviations 5.3 4.2 6.9 7.0 8.4 Number 13 15 21 47 49 •Source Total Between Within Degrees 144 4 140 Sum of Square Mean Square Variance ratio 2.37 Not significant 7,775 493 7,282 1 2 3 . 3 5 2 . 0 - 5 9 - TABLE 1 1 . F i b r e length values f o r various sections i n a mountain-type Douglas f i r stem. P o s i t i o n i n Heartwood -^^^ the cross Included Included Heartwood Sapwood ^ ^ ~ ^ s e c t i o n Sapwood Sapwood Number^-^^^ A B C D S (Units) 1 51 1 0 6 1 2 0 77 8 5 2 69 1 0 0 83 115 125 3 8 5 8 3 112 97 95 4 80 97 1 0 9 86 87 5 7 0 7 4 77 96 118 6 75 75 98 92 105 7 78 87 85 1 3 0 1 1 0 8 95 7 8 107 115 111 9 82 86 111 1 2 3 1 3 2 1 0 67 93 108 7 0 112 1 1 92 95 1 0 7 1 0 0 76 12 85 99 1 2 2 1 3 2 122 13 66 97 125 110 112 1 4 75 107 8 4 90 125 15 63 82 1 3 0 120 132 1 6 1 0 0 99 1 0 1 1 0 0 112 17 70 58 105 1 3 2 1 2 3 18 87 85 1 1 2 85 1 4 0 19 78 87 119 95 1 2 2 2 0 76 90 98 1 2 9 1 2 0 TOTAL: 1544 1 7 7 1 2113 2 0 9 4 2 2 6 4 Average: 7 7 . 2 8 8 . 6 105 .7 1 0 4 . 7 1 1 3 . 2 mm 33.03 3 . 4 8 4 . 1 5 4 . 1 1 4 . 4 4 - 6 0 - TABLE 1 2 . Alcohol-benzene, acetone, and ether s o l u b i l i t y of mountain- type Douglas f i r wood. v. Position in the ^s^cross section Extractive content ^ \ A B C D S 1 2 1 2 1 2 1 2 1 2 Alcohol-benzene solubles - % Acetone solubles - % Ether solubles - % 4 . 6 1 4.71 3 . 2 3 3 . 4 5 3.14 3 . 2 0 1 . 0 6 1 . 3 6 1 . 16 1 . 1 0 1 . 9 6 1 . 7 8 2 . 6 0 2 . 7 5 2 . 3 2 2 . 4 8 1 . 6 1 1 . 5 3 6 . 9 6 7 . 0 6 6 . 0 4 6.16 6.08 6 . 2 0 2 . 2 5 2 . 2 9 1 . 9 1 1 . 7 6 1 . 9 5 1 . 8 5 TABLE 13. Creosote retentions of mountain-type Douglas f i r heartwood, included sapwood, and sapwood, following a 240-hour extraction in different solvents. Replicates Kind of Wood: Duration of Type.of Included Sapwood C Extraction Solvent Heartwood 1 D (Hours) Typed of extractions: Soxhlet Hot Soxhlet Hot Retentions (grams) 60 Alcohol-benzene 6 0 Ether 1 .69 .59 .45 .49 60 Acetone 2 .64 .73 .46 .62 60 Water 220 Alcohol-benz ene 10 Alcohol 1 .64 .55 .64 . 4 2 10 Water 2 .73 .51 .47 .48 230 0.1% Sodium 1 .64 .70 .55:: .61 10 hydroxide 2 .69 .65 .58 .70 Water 1 .69 .67 . .58 .63 240 Water 2 .61 .66 .76 .60 1 .12 .09 .07 .07 2 .10 .08 .08 None Control (no extraction) 3 .09 .08 .06 .09 4 .10 .11 .06 .06 5 .09 .12 .09 .05 AVERAGE: 0.10 0.07 Sapwood - 240-hour hot - Control Extracted water extraction .395 .448 Retention (grams) .354 .498 .432 .490 F i g . I. D iagram of a bordered pit (15,25). Mix X A . Bordered pit as s e e n on a r a d i a l s ec t ion . B. Bordered p i t -pa i r as seen on either tangential or c ross sec t ion . a . A p e r t u r e . b . T o r u s . c. A n n u l u s . C. Bo rde red pi t in a s p i r a t e d condition. D. Front v iew of a t o r u s and pit membrane . F i g . 4 . R a t e o f a b s o r p t i o n o f c r e o s o t e i n m o u n t a i n - t y p e D o u g l a s f i r s a p w o o d . ( S ) -v3 I Time in h o u r s (A E o 1.0 2.5 £ a o> c 2.0 o or 1.5 1.0 Fig. 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. Q L E G E N D ; R a d i a l . T a n g e n t i a l . , ro I In a l l d i r e c t i o n s . L o n g i t u d i n a l I I A v e r a g e . Q Sapwoo d S Hear twoo 'd I n c l u d e d sapwood Included sapwood D C B Heartwood A P o s i t i o n in the c r o s s s e c t i o n . 4.0 - a* t c o •?= c <o % or 2.5 2.0. 1.5 1.0 . 5 - X X X X X X X X F i g . 6 E f f e c t o f p r e s s u r e a n d t e m p e r a t u r e on c r e o s o t e r e t e n t i o n i n a m o u n t a i n - t y p e D o u g l a s f i r s t e m . L E G E N D : 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 emp. , 10 0 p s i . pressure. 2 l 2 ° F . t e m p . , 100psi . p ressure . i | | Average. i V O o Sapwood S Heartwood D Included Sapwood C Included Sapwood B Heartwood A P o s i t i o n in the c r o s s s e c t i o n . £ o F i g . 7 . T h e i n f l u e n c e o f p r e s s u r e a n d t e m p e r a t u r e o n c r e o s o t e r e t e n t i o n i n a m o u n t a i n - t y p e D o u g l a s f i r s t e m . <D 4 . d 3.0 S a p w o o d ( S ) 2.0 1.0 Inc luded sapwood (C) Included sapwood (B) H e a r t w o o d (A) Hear twood (D) 7 0 15 212 15 70 100 212 Temperature - ° F . 100 Pressure - ps i . F i g . 8 . I n f l u e n c e o f p r e s s u r e a n d t e m p e r a t u r e o n c r e o s o t e r e t e n t i o n i n m o u n t a i n - t y p e D o u g l a s f i r s a p w o o d a n d h e a r t w o o d . IQO ps i . pressure MJ2. oil o . JUmos pJiJL r i c _ J? rJi.su re: L E G E N D Sapwood (S) H e a r t w o o d (H) Z\1 e< 70 ̂ FM^nTj3_§.LStiir— - 70 212 Atmospheric Temperature -°F. l O O p s i Pressure. - 3 5 - Fig. 9. Creosote retentions and some physical and chemical properties of a mountain' type Douglas fir stem at five positions A . Creosote re ten t ion . frl the CTOSS S e c t i o n . C. P e r c e n t summerwood. T3 I ~ o 30 E . Alcohol - be nzene and a c e t o n e - s o l u b l e ex t r ac t i ve content F. E t h e r - soluble extractive . content 3* 9 O CO CD UJ Number of r e s i n d u c t s per square inch A Heartwood B C D E Included sapwood Incl.sapwood Heartwood Sapwood Pith P o s i t i o n in the cross section. Bark . F i g . 10. C o r r e l a t i o n b e t w e e n c r e o s o t e r e t e n t i o n a n d a l c o h o l - b e n z e n e s o l u b l e s o f m o u n t a i n - type D o u g l a s f i r h e a r t w o o d . I 2 3 4 5 6 7 8 A l c o h o l - b e n z e n e solubles % . o o M E 2.25 c o o o.25 F i g . II. R e l a t i o n s h i p b e t w e e n c r e o s o t e r e t e n t i o n a n d e t h e r s o l u b l e s o f a m o u n t a i n - t y p e D o u g l a s f i r h e a r t w o o d . c o c £.201 .15 i P> I .10 . 05 7 8 Ether solubles % . u u CO E o ^.25 i c o F i g . 12. R e l a t i o n s h i p b e t w e e n c r e o s o t e r e t e n t i o n a n d a c e t o n e - s o l u b l e e x t r a c t i v e c o n t e n t o f m o u n t a i n t y p e D o u g l a s f i r h e a r t w o o d . .15 Y= O.III4-O.OI0I x SEE=0.0I6 r = . 85 10 .05 6 7 Acetone so lub les % . 8

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