g m. U. S. Department of Agriculture, Forest Service FOREST PRODUCTS LABORATORY In cooperation with the University of Wisconsin MADISON, WISCONSIN £ r ', ■ 1 - FL LIB. >-T$ DEPT. U.S. DEPOSITC THE FOREST PRODUCTS LABORATORY By F. J. CHAMPION Assistant Technical Writer April, 1932 Digitized by the Internet Archive in 2013 http://archive.org/details/foslaOOfore C\J crv u © o -p o o 13 © © iH O o o -p g o t CD 43 o -p at © O £ cr\ © CM CVI © THE FOREST PRODUCTS LA30RATORY- F. J. Champion Research in forest products is a vital element in any farsighted job of forest administration. Its aim is maximum efficiency in using existing and projected forest stands and adapting them to the changing needs of the nation. This general purpose guides the work of the Forest Products Laboratory at Had is on, Wis., a part of the U. S. Forest Service. Tiie Laboratory was established in 1910 — just five years after the present Forest Service was organized in the Department of Agriculture. At tnat time no other nation — however old in the practice of forestry — was engaged in any comprehensive program of researcn in forest products. Under a coop^ra five arrangement tne University of Wisconsin erected the Laboratory building and agreed to contribute light, heat, and power to the maintenance of Laboratory operation. Organizatio n At present the Forest Products Laboratory is organ- ized for research on (l) growth of wood as it affects its properties and ultimate utility, (3) logging and milling prac- tices, (3) selection and preparation (grading, seasoning, etc.) of ^ood for use requirements, (4) internal and surface treat- ment of wood, (5) mechanical adaptation of wood to construc- tion and fabrication, and (5) conversion of --ood into pulp and paper. For purposes of administration tnese lines of research are carried on by a slightly greater number of Laboratory section;',, viz., the sections known as Silvieultural Relations, Timber Physics, Timber Mechanics, Industrial Investigations, Wood preservation, Derived Products, and Pulp and Paper. An office of Forest Patnoloiry is .maintained at the Laboratory by the Bureau of Plant Industry, Department of Agriculture. A section for Operation administers person- nel, quarters, and materials, and the section called Publica- tion of Results, serves tne purpose its nawe would indicate. —This paper was prepa red for publication in Tne military engineer . R940 -1- C-rowtn Studies In vie 1 *? of the keen competition of other structural tateriels it is plain t tat not only ">ust wood be a I t ;d to use requirements by proper selection of species and quality and proper seasoning , but also it must in many cases be grown with a specific use in mind. One of the functions of the Forest Products Laboratory's section of Silvi cultural Relations is to determine the effect of various site condi- tio:, uch as soil, precipitation, and spacing, in the forest nd upon the physical properties of wood. The spacing tor, botn as a part of planting operations and as con- trolled by thinning practices, is extremely important in the production of wood naving predictable and desirable proper- ties. It nas oeen found, for instance, that in scuta, 1 , nine the conditions productive of dense, strong wood for structural purposes are a moist site, close spacing in til stand, and protection from fire. Cn tne other nana, in the 8 species, light- weight wood of moderate strength suitable for Less exacting requirements — say pulping — c< n pro- duced -ainly by open spacing of the stand, together with equate fire protection. In contrast to the growth of conifers, which tend to produce their strongest, heaviest wood in relatively close stands, nardwoods produce their strongest material when sus- tained or increasingly rapid growth occurs in open stands or ; ; tne result of thinnings. Naval Stores "'or]^ The determination of growth-strength relations i. but one function of the section oi Silvicultural Relatione. This section is engaged in studies of the production of tur- pentine and rosin fro- the southern pines, with results of considerable: significance to date. It lias oeen found that the cutting of a weekly streak or chip one-quarter inch high at txie top of the usual turpentine ' ! i->co" i;. in tne long run fully as productive of tne rav> material, oleoresin, as a streak one-naif or even tnree-quarters incn high. Toe advan- tage of thus providing for a numbei of years' additional leasing period for tne trees is obvious. rnis doctrine, as wel\ as tiie Forest Service policy of working only tree Vnc.iee in diameter ana larger is now Deiiig steadily incor- porated into woods practice in the -sin naval stora i c ions of Soutn Carolina, Georgia, and Florida. R940 Wood Identification Many species of wood may be identified as readily dy minute cell structure as by the botanical characteristics of tee living tree. Tne Silvicul tural Relations section of the Forest Products Laboratory is official government head- quarters for wood identification on this basis. Largely originating in controversies incident to the marketing of forest products of all kinds, aoout 3,000 wood samples per year come to the section for an authoritative identification, Frequently costly litigation hinges upon the result of an examination of sawdust, wood flour, or a few slivers. Wood Seasoning The Forest Products Laboratory's section of Timber Physics is concerned with seasoning, an extremely important factor in the success of wood as either structural or finish material. Botn air seasoning and drying in kilns are studied. Tiie section has worked out the basic principles involved in drying tne various classes of lumber ranging from tne lowland hardwoods to the least refractory of the softwoods. Special studies on major commercial species are being carried on and published as rapidly as tne program will permit. Tne aim of kiln drying schedules is, of course, rapid elimination of surplus moisture — the cause of shrinking and swelling and decay — without the introduction of checks, warping, kiln stain, and other effects of badly tempered drying. Although tne general principles of ventilation and yard sanitation for tne successful air seasoning of wood have oeen widely disseminated by the Laboratory, recent surveys indicate that in general the conditions of yarding, storage, and sniprr.ent are operating to the disadvantage of wood in many parts of the country and that there is urgent need for extension of good practice to correct a most unfortuna.te situation. One of tne main obstacles to the proper control of moisture content in lumber has oeen the lack of any means of determining moisture content by other than slow and not especially satisfactory -ethods. This obstacle has been re- moved by the Forest Products Laboratory with the recent inven- tion of an electrical moisture-content meter that is simple, portable, economical in construction and operation, and accurate to 1 percent. Its effective range (7 to 24 per- cent) corresponds closely to the range of wood moisture con- tent that is most critical in use. Thin instrument, called R940 -G- 2M1996SF Test of a built-up "bean with glued larai nations. liodern wood re- search looks to the aore effective production and utilization of composite members. -the "blinker" because of tne two flashing neon bulbs that indicate relative wetness or dryness, is now being manufac- tured and sold commercially. A study of the moisture content range in various parts of dwellings in five distinct climatic regions of the United States has yielded information on optimum moisture content for the installation of wood in dwellings. Tne find- ings will be released soon to contractors, millwork manufac- turers, furniture makers, and others concerned with tne proper seasoning, handling, and use of wood in relation to cli] at: conditions. St re ngth Studies A large and important section of the Laboratory is the section of Timber Mechanics. Over 60 percent of tne lumber produced in tne United States is used in building construction, about half going to the farm and half into urban residences and industrial buildings. In this hi ;hly competitive field, accurate strength data on wood and its structural combinations is essential. '"bod has lost much ground to other materials because of antiquated methods of design and rule- of- t numb specifications. To meet the need for strenj th data the Forest Products Laboratory mechanics laboratory has carried out tests since 1910 that nave made it possible to publish com- plete information on the strength, weight, and shrinkage of no less than 164 native woods. These data, embracing the results of tests of compression parallel to grain, static bending, impact bending, compression perpendicular to grain, hardness, shear parallel to grain, cleavage, tension perpen- dicular to grain, tension parallel to grain, shrinkage, and specific gravity, have been made on small, clear specimens of both green and air-dry wood. In addition to these test , much work has been and is being done on timbers in structural sizes, and special equipment and personnel have been devoted to the working out of the engineerin principles involved in the construction of wooden containers, aircraft members, and recently, frame buildings. Fundamental -orinciples of box and crate construction have been worked out with special equipment including i vibrating table and a 14- foot box- testing drum capable of testing boxes up to 1,500 pounds in weight and 4 feet in cube, as well as by standard compression and drop tests. Tne results R9- -4- ZM22077? The 1^-foot "box druU| in which thousands of shipping containers have "been tested to establish the principles of efficient , econo;aical design and nailing. of this research have been published in a complete manual. The problems of transportation hazards of car movement havi been attacked, with results that have shown the way to ship- ping agencies entering on intensive studies in this field. By means of full-scale tests on typical wall panels., made possible in part by a million-pound testing machine, it has been possible for the Laooratory to indicate elementary means of sheathing and bracing to increase the rigidity of house walls by as much as 400 percent above that currently obtained. The tests were prompted in part by examination of buildings affected by severe storms in various parts of the United States. The studies of the use of wood in aircraft, under- taken during the late war, gave birth to several of the Forest Products Laboratory's main lines of research. This subject was dealt with by G. W. Trayer in an article in The Uilitaiy Engineer for November-December, 1929. Typical of the Forest Products Laboratory's researches in the engineering use of wood were the recently concluded tests of the design of bolted and fish-plated timber joints on Douglas fir, southern pine, spruce, oak, and maple fastened with steel bolts of diameters up to one inch. Since disastrous failures of wood construction often occur as a result of faulty jointing, the engineering value of this study is obvious. In so simple a question as the strength in tension of a single- bolted joint in wood, engineering nandbooks give data, varying by as much as 600 percent. As a result of the tests, the allowaole stress in joints in direct tension or at any angle with the grain of the wood can be calculated from the diameter, length, and number of bolts. Steel fish plates replaci. wood cleats were found to increase the efficiency of joints 25 percent. Logging a nd Milli ng Stud ies The section of Industrial Investigations is con- cerned with the economics of small sawmill and logging opera- tions, the use of ready-cut (small-dimension) stock by industries, the refinement of grading practices, and tne utilization of neglected species. Up to a few years ago when the passing of the virgin timber became a reality and tne snort or continuous crop operation of forests began to be talked about tne lumbermen, however thrifty, nad little information on tne actual costs of handling trees and logs of R940 _5_ ZM223803 1 Testing a laminated wood arch for deflection and maximum end load. various diameter Classen and. grades. The section of Industrial Investigations has developed this type of infor- mation for the Lake States, Appalachian, Arkansas, California, and Coastal Plains regions. For example, it has been found that in the second-growth shortleaf and loblolly type of the southern pine forest region, every thousand feet of lumber cut fror trees 10 inches in diameter a loss of $3.29 is incurred, not including stumpa.ge, as compared, to a profit of ^11.73 for 24-inch trees. In recently inaugurated studies of the small sawmill — an important economic unit in some forest regions — it has been found that the operators ordinarily ignore items amount- ing to some $2,50 per tnousand board feet or from 9 to 22 percent of the total cost, and that the yield of salable lumber can be increased by as much as $1.60 per thousand by greater- than- usual care in adjustment of the mill setworks. This information is being extended to the small operator largely through state or local agencies. Special ccmpila.tions of the strength and utiliza- tion data of several neglected tree species, notably aspen, western larch, ana western hemlock have been undertaken recently, lar£ Ly o:i the basis of data already available out not hitherto exploited. The collected information is beis. released to the public as rapidly as possible in the form of D epa r tmen t o f A gr i e ul tar e t e chni ca 1 bul 1 e t ins . Preserv ati ve , Paints, and Accessory Material s One of trie most productive fields in wnich forest •products research nas been engaged is the modifying of wood properties through the use of chemical preservatives (e as creosote and zinc cnloride), paints and coatings, fire retardants, and glues. This is t le province of the section of Wood Preservation. The section has taken a leading part in the development of an art — wood treating — already well estaelisned in industry. Through an increasing amount of use of treated ties a representative group comprising aoout half the railroads of the United States has is tae last twenty years reduced average tie replacements from nearly 250 per mile of track per year to about 180 per mile of track per year. The actual saving to ail railroads through tie "treat- ing is estimated at $145,000 per day. In addition to experi- mental impregnation work p the Laboratory exercises leadership in the field of wood preservation in acting as headquarters for service records of over a million railroad cross ties R940 -6- ZM220VH The Laboratory has set up paint test fences for observation in eleven climatic regions of the United States, and. a large number of posts, poles, etc., treated and untreated, that are in service (and hence undergoing the most conclusive and satisfactory possible test of durability) all over the United States. In the field of f ire-retardants the Forest Products Laboratory Has developed a standard test for inflammability of rood that is now accepted by leading testing agencies. The Laboratory is using the special apparatus and technic in an extensive and thorough examination of chemicals for making wood resistant to fire. In the same section the only comprehensive re- searches on the gluing of wood in this country have been carried on. Tne principles involved in proper interrelation of glue viscosity, temperature, assembly time, and pressure nave been worked out so that joints as strong as the wood itself or stronger can regularly be obtained by scientific glue- room practice with all but the most refractory woods. Tne technic of gluing plywood has been highly developed and recently a chemical treatment has been devised for blood albumin glue that nas protected plywood joints from any appreciable loss of strength through decay in a moisture- saturated atmosphere for five years. As a result of seven years of exposure tests of 15 species of wood on eleven test "fences" in various cli- matic regions of tne country, the section of Wood Preservation has been able to group tne common woods with respect to paint- ing qualities and to lay the groundwork for real development of paints and coatings for wood. Chemical Studie s Tne Forest Products Laboratory's section of Derived Products is engaged mainly in fundamental studies of tiie chemistry of cellulose and lignin, the most important chemical constituents of wood. Although cellulose is used daily in the production of pulp, paper, lacquers, rayon, and viscose and is skillfully controlled within the limitations of the various processes, little enough is known of its exact chemical nature. The extension of chemical conversion to forest thin- nings, unused species, and logging wastes will necessarily come, not throug'h chance discovery but through a clearer knowledge of cellulose and its chemical relationships. R940 -7- ZU2Q$iQ7 Research on fire-resistant treatments of wood. Lignin is relatively ne^ on the Derived products section's research program. The substance is trie bete noir of practically all processes for refining cellulose and yet practically all that is known or suspected about it is that it has several Marked points of similarity to cellulose. Lignin may prove to be as ugly chemically as its history to date would indicate but it is hoped that it will repay better acauaintance. The Derived Products section is also engaged in studies of the extractives — the free water-soluble sub- stances found in some woods — and in studies of the toxicity to decay organisms of various chemicals. The latter study is a part of the search for the "perfect" preservative — that is, one that is cheap, toxic to fungi, but not too much so to live stock, non-corrosive, non-leaching, etc. Pulp and Paper Studies The Forest Products Laboratory's Pulp and Paper section carries on studies calculated to improve existin pulping and paper-making methods, to produce new methods, and to extend the benefits of various methods to hitherto neglected but abundant species, and to various mill and industrial and wood wastes. Notable success has been attained in widening the outlets for the southern pines. Originally producing only kraft papers these woods, it is known now, can be used in the production of book, writing, grease-proof, glassine, and other economically important papers. An entirely new process — combining the desirable attributes of both cnemical and mechanical pulping — was devised to produce high yields of cheap print paper from both hardwoods and softwoods. This process, involving the use of the rod mill — a device borrowed from the metallurgical industries — has been installed in numerous pulp and paper mills. The Pulp and Paper section is now extending its researches in- tensively to tne western woods, particularly to western mill wastes. War A ctivi ties Like many an individual the Forest Products Laboratory found the late war to be tine greatest single stimulus of its history and the greatest test of its worth to the Nation. When war was declared the Laboratory tai R940 -8- Z122507F Charging an experimental digester with pulping chips. Efficient conversion of a great variety of .American wood species into pulp and paper products of good quality is needed to solve the problem of the Nation's permanent pulpwood supply. certain that its services would be needed, but was a little vague as to just where to inaugurate work that would help to win the war. The indecision was not of long duration. Officers of both Army and Navy soon became aware that the Laboratory was the proper reference point for many of materials problems and the Laboratory was overwhelmed with requests for wood utilization information that demanded answers "at the earliest possible moment." Between June, 1917, and November, 1918, it was necessary to increase the force from 85 to 450 and to operate on a three- shift basis. Seventy to 75 percent of tne Laboratory's war work pertained to aircraft. When tne United States entered the War the greater part of the production of airplane spruce had already been contracted for by the British, French, and Italian governments. At the same time aircraft engineers were not ready to accept kiln dried material. The Forest Products Laboratory developed a successful kiln-drying schedule for three- inch airplane spruce plank that seasoned tne material in from 20 to 45 days instead of the one to two years required for air seasoning. When tne Spruce Production Division was organized in the Signal Corps, the Laboratory was called upon to design dry-kiln equipment. Twenty-four kilns designed by the Laboratory dry-kiln specialists operated successfully with a daily output of 40 thousand board feet of wing mate- rial per day from July, 1918, until the end of the war. Tests of plywood inaugurated at the Laboratory in connection with aircraft production form tne basis of all present water-resistant plywood specifications used in air- plane design in both Army and Navy. War work on both the gluing and moisture proofing of wooden propellors gave birth to the present Forest Products Laboratory glue laboratory and led to the discovery of tne preeminence of aluminu" leaf and aluminum powders for moisture-excluding coatings. During the war and in winding up studies then started the field of wood use in aircraft has been much more fully investigated than has the use of metals in the same industry. Demands of the Ordnance Department made it neces- sary for tne Forest Products Laboratory to inaugurate the container testing division tnat functions for the benefit of industry today. Problems that were solved included those pertaining to the design of a cargo-space-saving packing case for Browning Automatic rifles, and wooden containers for marmites, hand grenades, high explosives, shells, and artillery harness. R940 -9- Miscellaneous tests tnat are recorded in t i Laboratory's reports had to do with the strength of cannon ramrods, proper handles for intrenching tools, wooden du noses used in the snipment of shrapnel shells, the develop- ment of new species of wood for wooden-ship treenails, •■ t - development of reliable sources for gas-mask absorptive charcoal . After tne Armistice the Laboratory staff was re- duced to somewhere near its present strength of aoout 200 persons . Coonerative Research Tne Forest Products Laboratory research program is supported by Congressional appropriation and planned on a long-time basis to meet and anticipate both the needs of ind i try and tne needs of the men administering the national forests. No routine testing is undertaken, but occasionally researcnes are undertaken on a cooperative basis wnen a large group of individuals or an entire industry seems likely to benefit. In such cases the cooperating firm, individual, or a b eney pays from 50 to 100 percent of the actual costs incurred in the research. Publications The Forest Products Laboratory has published its findings regularly in the form of Department of Agriculture bulletins, circulars, and leaflets, and in less formal mimeographed and multigraphed reports and technical notes. Tne publications section will gladly supply a list of publi- cations pertaining to any research section or group of sec- tions, and will place qualified individuals on its mailing list to receive a sera-annual list of publications or publications of a specified topic. A few of the Laboratory's publications are as follows: "Guidebook for tne Identification of Woods Used for Ties and Timbers," U.S. Forest Service, 30 cents. "Comparative Strengtn Properties of Woods Grown in the United States," U.S.D.A. Technical Bulletin 158, 10 cents. "Kiln Drying Handbook," U.S.D.A. Bulletin 1136, 30 cents R940 _io- "Mechanical Properties of Woods Grown in the United Stater,," U.S.D.A. Bulletin 556, 10 cents, "Properties of Western Hemlock end Their Relation to V of the Wood.," U.S.D.A. Technical Bulletin 133, 30 cents. "Tests of Large Timber Columns and Presentation of the For Products Laboratory Column Formula," U.S.D.A. Technical Bulletin 167, 15 cents. "The Gluing of ""ood," U.S.D.A. Bulletin 1500, 25 cents. "Principles of Box and Crate Construction," U.S.D.A. Technical Bulletin 171, 55 cents. "T-ie Air Seasoning of Wood," U.S.D.A. Technical Bulletin 174 55 cents. "Gluing Wood in Aircraft Manufacture," U.S.D.A* Technical Bulletin 205, 25 cents. "Kiln Drying of Southern Yellow Pine Lumber," U.S.D.A. Technical Bulletin 165, 20 cents. "Effectiveness of Moisture-Excluding Coatings on 5005," U.S.D.A. Circular 128, 10 cents. "Decays and Discolora tions in Airplane Woods," U.S.D.A. Bulletin 1128, 20 cents. "The Preservative Treatment of Far- Timbers," Farmers' Bulletin 744, 5 cents. "Control of Decay in Pulp and Pulp^ood," U.S.D.A. Bulletin 12SS, 25 cents. "Suitability of American Woods for Paper Pule," U.S.D.A. Bulletin 1485, 20 cents. "Properties of Western Larch and Their Relation to Uses of tile Wood," U.S.D.A. Technical Bulletin , cents. Tiie above publications may be obtained from the Superintendent of Documents, Governs at Printing Of i Washington, D. C. , at tae prices indicated. R540 -11- UNIVERSITY OF FLORIDA 3 1262 08926 9517