>i 
 
 7 
 
 possibilities of increasing the use 
 of hardwoods to meet puepwocd 
 
 requirements 
 
 May 1946 
 
 
 . / 
 
 
 
 -■-' 
 
 sm If M» 
 
 ft 
 
 No. R1614 
 
 UNITED STATES DEPARTMENT OF AGRICULTURE 
 
 FOREST SERVICE 
 
 FOREST PRODUCTS LABORATORY 
 
 Madison, Wisconsin 
 
 In Cooperation with the University of Wisconsin 
 
POSSIBILITIES OF i THE USE OF CDS TO 
 
 FUL1 lOOD REQUIH :- 
 
 By 
 
 J. ' . - ' . '■, Chemical Engine, r 
 
 For..st Products Laboratory, .£ Forest Service 
 
 U. S. Department of sericulture 
 
 Abstract 
 
 Predictions of increased pi .ad board demands for 
 the immediate future raise auestions regarding possibl - rces 
 of fibrous row material to- satisfy anticipated requirements. 
 
 use the cheapest source of paper-making fiber will probably 
 continue to be wood and because readily available supplies of 
 preferred long-fibcred species arc inadequate, new resources of 
 nulpwood will need to be developed if domestic supplies are to 
 be utilized. A promising oulpwood source lies in currently 
 secondary species and low-grade wood. Hardwoods make up the bulk 
 of secondary species and their use is necessary to realize a badly 
 needed improvement in silviculture in the woods. Although hard- 
 woods have been used to advantage in small amounts in the pulp and 
 paper industry for many years, it is only within the last few y 
 that advancements in technical knowledge have been made to overcome 
 certain difficulties in hardwood harvesting and processing and in 
 pulp- and paper-making procedures. These advances have improved 
 the possibilities of increased utilization of hardwoods • 
 
 rly 150 years ago the English economic world was introduced 
 to the startling theory which predicted alarming poverty if population 
 increases did not become commensurate with the more moderate increases in 
 means of subsistence. However, advances in agricultural and other tech- 
 nologies and in transportation tended to disprove this famous theory of 
 Malthus« Today, serious shortages again confront the United States and the 
 world. Of particular interest to the Forest Products Laboratory is the 
 shortage of paper and papcrboard, since these are chiefly products of the 
 forest. The demands for these products are not being met and the predicted 
 demands in the near future exceed considerably the readily available sup- 
 plies of the preferred long-fibered raw material. Although the situation 
 is unlike that described by Mai thus, it will be shown that, technological 
 developments con again help meet the present and prospective shortages, at 
 "t the paper and board shortages. 
 
 — "resented at a meeting of the Wisconsin Press Association at Milwaukee j 
 •'.'is., May 17, 1946. 
 
 9 
 
 — intained at Madison, ".'is., in cooperation with the University cf 'Visconsin. 
 Report :.'o. R1614 
 
As you know, the pulp and paper industry in the United States 
 has had a rather amazing growth during this century. A large increase in 
 paper consumption has been shown in each decade. In the period from 1999 
 to 1945 the consumption of paper and board has increased from slightly 
 over 2 million tons to about 20 million tons. It has been predicted con- 
 servatively that paper and board consumption will be 24 million tons by 
 1950. During the period of 1899 to 1943 the per capita consumption of 
 paper and board increased from 58 to 288 pounds, although it reached a 
 high of 309 pounds in 1941; it is estimated that this value will be 330 
 pounds by 1950. It is of interest, incidentally, to recognize that a 
 close correlation exists between consumers' expenditures for nondurable 
 goods and services and paper consumption. 
 
 Accepting the predicted increase of 20 percent in parer and 
 board consumption by 1950, the question then arises as to where this 
 increase is to come from. It seems likely new that the added require- 
 ments will be met to a greater or lesser degree by the following alter- 
 natives, assuming that wood will continue to be the cheapest source of 
 primary fibrous raw material: 
 
 (a) Importing more pulpwood, pulp, and paper. 
 
 (b) Using more waste paper. 
 
 (c) Increasing domestic pulpwood production by going farther 
 afield for preferred long-fibered species, by using new species, or by 
 using more of the little-used species. 
 
 Part of the increased requirements will undoubtedly be met by 
 increased imports, although there are increasing demands elsewhere for 
 Scandinavian pulp and paper products and it will be a few years before 
 those countries have recovered from the effects of World War II. In this 
 connection it is interesting to note that before the war the amount of 
 paper imported or made from imported pulpwood and pulp nearly equaled the 
 amount of paper made from domestic pulpwood. Waste paper will continue to 
 be used in large quantities in numerous grades of paper but it is doubtful 
 if the war-time collection level can be maintained unless the situation 
 becomes critical. Thus a large part of the increased requirements for the 
 future will probably need to be met by domestic pulpwood. 
 
 During 1945 close to 86 percent of the pulpwood consumed in the 
 United States was in the form of the preferred long-fibered species, the 
 softwoods. The possibilities of cutting more preferred softwood pulpwood 
 and maintaining this high percentage of long-fibered wood appear to be 
 limited because additional supplies of the desired species are not readily 
 available or cutting at an increased rate will impair the forests. In the 
 Northeast, for example, the available supplies of softwoods have been 
 inadequate for years and a considerable percentage, 31 percent in 1944, 
 of the softwood pulpwood consumed has been imported. A similar situation 
 exists in the Lake States. In the South there is a sufficient over-all 
 supply of pine pulpwood for the future, but concentration of mills in 
 certain areas has reduced the availability of the pine, or cutting at a 
 higher rate is contrary to good forest practice. Finally, the supplies 
 
 Rep art No. R1614 -2- 
 
f the pri r ' d hemlock in the Northwest have become singly less 
 
 available s,o I I an increase under past conditions is Improbable. 
 all regions, howi •.■» r, ' ■ n La br mendous supply of low-grad wood and 
 little-used species whose utilization is imperative if badly needed 
 
 nents in the c< I one and future productivity of the forest are 
 
 to be realized. In tl rtheast, Lake States, and the South thi CIUS 
 
 for^ sources are largely in the form of the br^ -] .fed hardwoods. 
 
 This source of wood a rs to offer an attractive possibility for increasing 
 
 supply oj pulpwood. Hemlock and Douglas-fir lc and mill 
 
 comprise the probable source of pulpy/ ood in the Northwest* Thus, the most 
 likely resources in three of the four major pulpJ gions exist in r - 
 
 woods • 
 
 Before discussing the possibilities of utilizing hardwoods to 
 t a substantial portion of present and future pulpwood r< ts, 
 
 it is advantageous to review the history of the use of wood as a fibrous 
 raw material for paper i» order to heir determine possible future trends 
 in oulpwood use. The first wood species used in t] r industry 
 
 v/ere poolar and basswood, both hardwood species although soft in texture. 
 These woods were particularly suited for soda pulping, the first chemical 
 pulping process. The invention of the sulfite pulping pre-' d develop- 
 
 ments in °:roundy/ood pulping soon changed the preference to spruce. In 
 1899 spruce alone made up 76 percent of all ulpwood consumed. Because 
 
 the supplies of spruce did not prove inexhaustible end because pai r 
 demands v/cre increasing rapidly, other species had to be used to meet 
 these demands, ^n this way Eastern and iestern hemlock, Southern yellow 
 pine, balsam and white fir, and jack nine were added to the list of so- 
 called pulping species. To the orJ ] rdwoods, r i swood, 
 v/cre added small amounts of yellow-poplar, gum, chestnut, birch, maple, 
 and cottonwood. These additions came about as p. result of both economic 
 pressure and advances in technical knowledge. The importance of spruce 
 
 in the over-all picture has thus diminished and in 1941 spruce rented 
 
 only 22 percent of the U. S. pulpwood consumption. It is inescapable, 
 however, that the trend has been for now, long-fibered species like Wester 
 hemlock or southern pine to satisfy the incr asing ; - ads i'or pulpwood* 
 
 It is now natural to question why hardwoods I sscd en 
 
 in spite of their vailability in large quantities. Two reasons stand out 
 for this rejection. Th s re: (l) Hardwoods are difficult to 1 ad 
 
 prepare for pulping (particularly bark removal), and (2) hardwood fibers 
 arc short (on the aven -■ l/25 inch long in comparison with l/8 inch long 
 for softwood fibers) and have been used satisfactorily by oonventiom ] 
 methods only in a few grades of paper where strength is not 3 -.t, T- 
 
 question then arises as to whether these reasons still limit ~rd will 
 continue to handicap hardwoods. The answer to this second question is th. t 
 rdwood harvesting will probably always b* more difficult softwood 
 
 it hardwood pulps will probably never find usag re 
 
 the gr -t st strei Ls reeded, but r o t technical advai i lop- 
 
 men ts havi ■ nsid rable future promis re showing luch 
 
 Report No. RICH -3- 
 
wider use of short-fibered hardwoods than in the past. Discussion of a 
 few of these advances and developments will illustrate the possibility s 
 of increasing the use of hardwoods in the pulp and pai er industry. 
 
 Hardwood harvesting and processing is generally more costly 
 than that of softwoods because hardwoods are heavier and more difficult 
 to saw, handle, and debark. Improvements in mechanization and integrated 
 lagging are expected to reduce costs and difficulties. The hardwood 
 peeling season is shorter than for softwoods and hardwood bark is removed 
 with considerable difficulty at the mill. However, improved methods of 
 bark removal which may overcome this objection to hardwoods are being 
 developed. 
 
 Before the war hardwood pulps were used chiefly as soda pulp in 
 certain grades of book, writing, and printing papers, as sulfite pule in 
 printing, writing, end absorbent papers, and as semichemical pulp in cor- 
 rugating paper. The amounts of pulp made were not large and the use of 
 stmichcmical pulp was the only substantial advance made since 1925, The 
 hardwood soda pulp was used because its soft and bulky nature and its 
 short resilient fibers made papers with excellent printing characteristics. 
 The sulfite pulp was used as a filler nulp to improve paper formation and 
 surface properties, mainly because of its short fibers. The hardwood semi- 
 chemical pulps imparted a desirable stiffness to the corrugating poper. 
 All of these uses of the hardwood pulps depended on specific character- 
 istics of the hardwood fiber. These specific properties at the same tine 
 limited the use of hardwood oulp to the narrow field where strength was not 
 important. There have been recent developments, however, that indicate 
 that pulps made from hardwoods can find broader use, and that the possi- 
 bilities of increasing the utilization of hardwoods in the pulp and paeer 
 industry are definitely brighter now than at any time in the nast. 
 
 One imnortant development in hardwood pulping has been the 
 demonstration that many hardwoods can be pulped by the conventional sulfate 
 process to produce pulps having considerable strength and wide use possi- 
 bilities. Heretofore, the sulfate process has been applied chiefly to 
 northern and southern pines to produce the strong pine kraft pulps used in 
 wrapping paper and container board. The hardwood sulfate pulps are much 
 stronger than the soda pulps. One large northeastern mill has proven t® 
 its own satisfaction that bleached hardwood sulPato nulps can be used for 
 a maiority of the outlets now served by bleached softwood sulfite nulp 
 and has started construction of a mill to produce bleached sulfate from 
 birch, maple, and beech. At least two northeastern soda mills plan to 
 convert to sulfate pulping to improve the strength and utility of their 
 hardwood t-u1ps . During the war a "Wisconsin sulfate mill started, using 
 aspen to furnish part of its wood supply when nine and spruce resources 
 failed. The benefits obtained exceeded expectations and the mill is 
 continuing the pulping of aspen. One Ir.rge southern sulfate mill has 
 been pulping southern hardwoods for use in tissue papers; another is 
 pulping hardwoods for book paper. It has been shown experimentally at 
 the Forest Products Laboratory that certain proportions of hardwoods, say 
 10 percent, can be pulped in mixture with pine without sacrifice in oulo 
 
 Report No. R1614 -4- 
 
quality. General use of even rm, all proportions of hardwoods will provide 
 a possible outlet of ae nuch 08 a million cords annually in the pulp 
 industry in the South, In Q recent contest in Canada for the most prac- 
 tical method to use hardwoods in newsprint manufacture, th pris -winring 
 suggestion entailed the usu of semib! •ached sulfate oulp from birch, in 
 addition to asr\ n groundwood pulp to provide 40 percent oortion of 
 hardwoods in newsprint. Thus, the sulfate pulping process v/ith litt] 
 
 .-,c in conventional operation offers several attractive possibilities 
 for increasing hardwood utilisation* 
 
 th slight modifications, the sulfite process also offers 
 possibilities ^or increasing hardwood utilization over r nd above prc"- 
 usc. During th< war period it was n cognized that hardwood sulfite pulns 
 made according to the best practice had more use possibil it? 
 viously realized* For example, the quality of birch sulfite pulp is not 
 far from that of Eastern hemlock sulfite puIp. Hardwood sulfite pulp < Iso 
 has certain qualiti 3 which makes it a promising r 1 for chemical 
 
 conversion. 
 
 The conventional grour.dwood pulpinp procss likewise off 
 possibilities for th*., additional use of hardwoods. Luring the war sc- ral 
 '.'.'isconsin froundwood nulp mills used aspen gr^u^dweod puln to gr^at ad 
 
 roduct made by one of the rrrlls, a coated book raner, contained 
 50 nercent asper • While this usage was compelled by wartime demands, 
 certain definite advantages have been rocogrJ ad at least a port of 
 
 the wartime r T r .ins in the pre Auction of aspen pulps by th*. various m thods 
 is expected to be continued. Incidentally, the consumption of aspen has 
 doubled during the last few years, and the information obtained by its 
 forced use will increase the possibilities for its future utilizati^- . 
 
 By modifying the relatively new neutral sulfite semi chemical 
 pulping of hardwoods through addition of a stage of bleaching, it is 
 possible to partially o^.-ercome the low strength of hardwcod puIps. 
 Actually, hardwood pulps as strong' as standard pulps fro??, many long- 
 fibered species have been made in mill-scale demonstrations, Dev< lop- 
 ments in the s enichemical pulping process itself are being pursued in 
 several places. One large southern mill has started construction of 
 pulping facilities to produce hardwood s nical nulp for wider usage 
 
 than heretofore on the basis cf successful wart' • ration in a smaller 
 
 souther- 1 mill. Experiments at the Forest Products Laboratory ' 
 indicated the possibility of using hardwood semi chemical and roundwood 
 
 lps in mixture with soft pulps in the manufacture of rant. 
 
 Other work at ' Moratory has shown that a large numt r of southern 
 
 hardwoods are suitabl For producing an excellent quality of corrugating 
 board from semichemicol pul] made with sulfate pulping liquor. 
 
 During the last f rs the use of print in rs, partic- 
 
 ularly of tin coated type for magazines, ha s increased astonishingly and 
 
 titles are expected to bo used in the future. The hardwood pulps 
 hav xoellent possibility of fitting into this expansion because they 
 
 port No. R1614 -5- 
 
 
improve printing qualities. Development work recently started has as its 
 purpose improving the strength of hardwood papers by use of resin bonding. 
 If successful, this will increase the utilization of hardwood pulns. 
 
 Finally, some of the most attractive opportunities for 
 utilizing wood waste and low-grade material, including certain hardwoods, 
 exist in the field of coarse-fiber materials such as building board and 
 paper, insulating board, and roofing felt. Use of these products has 
 increased greatly during the past few years and this rapid expansion is 
 expected to continue. 
 
 Thus it aopears that the possibilities of increasing the use 
 of hardwoods in the pulp and paper industry are more favorable now than 
 at any previous time. The problems connected with hardwood utilization 
 are far from solved, however, and considerable technical advancement is 
 still needed before hardwoods nay be used to the best advantage* 
 
 Renort No. R1614 -6- 
 
M L.4 
 
 M I I I I I I 
 
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