Grading of structural timbers.-To permit the more efficient use of timber and also to enable the designing of timber structures with assurance of safety, structural grading rules in which defects are limited in accordance with their effect on strength were developed at the Laboratory. These have formed the basis for the grading rules of structural timber of various lumber associations and other organizations to which definite working stresses could be assigned."* A similar method of grading has recently been developed for lowgrade dimension stock which is largely used in house construction. These rules will permit the establishment of rules for low-grade stock so that definite working stresses can be assigned. Specifications and stresses for wood poles.-The Laboratory is represented on and has worked with an American Standards Association sectional committee concerned with specifications and stresses for wood poles. Northern white cedar, western red cedar, American chestnut, Douglas-fir (creosoted) have been considered. The standards 75 have been widely accepted by pole producers and users and by regulatory bodies. Strength values of various woods for use in airplane design.—As a basis for the design of wooden aircraft parts and members, a table of strength values of the different aircraft woods was prepared by the Laboratory. The special airplane design values take into account the quality of the material and its variation, provide a minimum density requirement, and include a consideration of the special effect of duration of stress. The design of data serve as standard 76 for the design of wooden aircraft members and parts in the United States. Army and Navy Specifications for aircraft woods. Specifications for various woods and plywood used in airplane construction have been issued by the different airplane divisions of the Army and Navy. Because of the critical requirements for woods used in airplane construction, the Laboratory has taken a major part in the preparation of these specifications for aircraft woods. Aircraft airworthiness.-The Civil Aeronautics Authority has recently prepared regulations pertaining to the selection of airplane woods and manufacture of the finished wood parts. These regulations " are based largely on information obtained from the Laboratory. Navy manual for inspection of aircraft wood and glue.-To aid the United States Navy Department in the proper selection, use, and standardization 78 of aircraft wood and glue the Laboratory in 1928 prepared a rather complete manual for use by inspectors of naval aircraft and naval material, assembly and repair officers of operating and maintenance organizations, and for instructional purposes. The Laboratory has recently completed revision of this manual to include all the latest information. Building codes.-A large proportion of the lumber manufactured is used in the building industry. The satisfactory and economical 74 "Guide to the Grading of Structural Timbers and the Determination of Working Stresses," 27 pp., Miscellaneous Publication 185, U. S. Government Printing Office, Washington, D. C., February 1934, 5 cents. 75 "American Standards for Ultimate Fiber Stresses of Wood Poles," A. S. A. 05a-1933, American Standards Association, New York City, 1933. 70 "Wood in Aircraft Construction," Aircraft Design Data Note 12, Bureau of Construction and Repair, U. S. Navy Department, Washington, D. C. 77"Aircraft Airworthiness," Report No. 15, Civil Aeronautics Authority, Washington, D. C., January 1940. 78 "Manual for the Inspection of Aircraft Wood and Glue for the U. S. Navy," U. s. Navy Department, Washington, D. C., Revised Edition, 1940. (In press.) use of this lumber is dependent largely upon reasonable and adequate building codes and regulations. The United States Department of Commerce issued some years ago recommended minimum requirements for small dwelling construction which have been widely used in preparing or revising building codes." The Laboratory had the major part in the preparation of the section of the publication pertaining to wood. The Laboratory is represented on the Building Code Correlating Committee of the American Standards Association which is now actively engaged in preparing a new code. The Laboratory and the National Lumber Manufacturers Association have accepted joint sponsorship of the Sectional Committee on Building Code Requirements for Wood of the American Standards Association. A preliminary draft for these requirements for submission to the sectional committee is now being prepared by the Laboratory. 80 The Laboratory has participated also in the development of the specifications covering methods of applying preservatives prepared by the American Wood Preservers' Association, the Federal Government, the National Door Manufacturers' Association, and others. Naval stores. As the result of extensive tests, approximately 1⁄44-inch chipping has been set up by the Laboratory as the standard 30 height per week to chip trees in naval stores operations. Increased vields and profits per tree, combined with better health and growth of the trees turpentined result from the use of the 1/4-inch chipping. Low chipping is now applied to both Government and privately owned timber. Moisture content of wood.-In order that wood may give satisfaction in use, it is essential that attention be given to the factor of moisture content. As a result of work done by the Laboratory, the Southern Pine Association 81 and the West Coast Lumbermen's Association 82 have included moisture-content limitations in grading rules for southern pine and Douglas-fir, respectively. Longitudinal shrinkage.-Longitudinal shrinkage from the green. to the oven-dry condition of 0.3 of 1 percent has been set up as the upper limit for normal wood and any shrinkage above that is considered as being due to some abnormality of the wood. This limit is based on a large number of measurements of wood of normal and abnormal structure. A minimum of not fewer than four annual rings of growth per inch of radius has been set up for the southern pines if excessive crooking due to uneven longitudinal shrinkage is to be avoided in otherwise normal wood. This was based on the results of numerous tests on the longitudinal shrinkage of southern pine wood of different rates of growth. Hardwood log grades.-In spite of the long need for accurate and uniform methods of grading hardwood logs the log trade has made little progress in the development of standard procedure. During the past year the Laboratory has taken the initiative and has "Recommended Minimum Requirements for Small Dwelling Construction," Building and Housing Publication No. 18, National Bureau of Standards, Ü. S. Government Printing Office, Washington, D. C., 1932, 10 cents. "More Turpentine, Less Scar, Better Pine," 4 pp., Leaflet 83, U. S. Government Printing Office, Washington, D. C., 5 cents. Standard Specifications for Southern Pine Lumber Conforming to American Lumber Standards." Southern Pine Association, New Orleans, La., July 1939. Standard Grading and Dressing Rules for Douglas-fir, Sitka Spruce, West Coast Hemlock, Western Red Cedar; American Lumber Standards Sizes and Grades," West Coast Lumbermen's Association, Seattle, Wash., July 1934. gone forward with basic studies in support of a new approach to quality classification of logs. When the log-buying program of the Northeastern Timber Salvage Administration was initiated in the fall of 1938 the Laboratory submitted its tentative draft of log grades, and with modifications it was adopted as the basis for log purchases. Two other log-buying agencies have adopted the principle suggested by the Laboratory. The results of studies to date give promise of a set of log grades that will be an acceptable standard for hardwood logs regardless of species or source. Ladder code.-The Forest Products Laboratory, through its representation on the American Standards Association Sectional Committee on Ladders, took an active part in the preparation of a safety code for the construction, care, and use of ladders. This code governs safe practice for ladders, and has been adopted as standard 83 by the American Standards Association. Terms for describing wood.-In discussing the properties and characteristics of different species of wood it is often desirable to describe them broadly by means of descriptive terms, rather than by quoting precise numerical values. There has been a long-felt need for precise terms to describe the various physical and mechanical properties of wood and to meet this need the Laboratory has developed a series of standard terms $4 for describing wood. Ten terms have been set up for each property, thus giving a relatively wide range, of expression. The general use of standard terms will result in more precise evaluation of the various important physical properties of wood as well as eliminate the confusion resulting from the use of indiscriminate or uncorrelated terms. Tool handles.-The Laboratory has from time to time prepared material for use in the formulation of specifications 85 for ax handles, pike poles, peavy handles, and so forth, of such species as ash and hickory. This material has been used by the National Bureau of Standards in the preparation of Simplified Practice Recommendations, by the Federal Government for purchase specifications, and by various manufacturers. Federal Specifications for boxes.-The Laboratory has taken an active part in the preparation of Federal Specifications for seven types of wood and fiber boxes: Nailed and Lock-Corner (NN-B-621a); Wire-bound (NN-B-631a); Cleated-Plywood Construction (NN-B-601): Cleated-Fiberboard (NN-B-591); Fiber. Solid (LLL-B-636a): Fiber, Corrugated (LLL-B-631a). Nailing schedule.-One of the developments resulting from the study of wooden boxes and crates is a nailing schedule 86 which gives the sizes and spacings of nails to use with different thicknesses of lumber. The schedule involves a classification of container woods into four groups according to nail-holding ability and other properties. All of the species within each group can be used interchangeably as far as the thickness of lumber and the size and spacing of nails are concerned. The sizes and spacings of nails recommended 83 "Safety Code for the Construction, Care, and Use of Ladders," A14-1935, American Standards Association. New York City. 1935. 84 "Standard Terms for Describing Wood." Journal of Forestry, No. 1, January 1938. 85 "Ash Handles: Simplified Practice Recommendation R76-40," "Hickory Handles: Simplified Practice Recommendation R77-27." National Bureau of Standards, U. S. Government Printing Office, Washington, D. C., 1940, 1928. 5 cents each. 88 "Principles of Box and Crate Construction," pp. 71, 107. Technical Bulletin 171, U. S. Government Printing Office, Washington, D. C., 1930, 55 cents. for each group are based on the thickness of the lumber and the relation between thickness of the piece through which the nail passes and the thickness of the piece holding the point of the nail. The classification of species was first made in 1913, and this classification together with the nailing recommendations have been widely accepted by practically all organizations interested in wooden containers. Plywood.-The increasing and wider use of plywood for construction purposes prompted the formulation of a Commercial Standard for Douglas-fir plywood. The Laboratory assisted in the preparation of this Commercial Standard 87 which covers moisture-resistance requirements, sizes, tolerances, inspection, manufacturing details, limitation of defects, and so forth. Glue. The Forest Products Laboratory participated in developing a Federal Specification 8 for animal glue. 88 89 Wood preservatives.-The Laboratory has actively participated in the formulation of the standard so specifications of the American Wood Preservers' Association for wood preservatives, particularly zine chloride and various creosote oils and in the preservative specifications of the National Door Manufacturers' Association. It has also assisted in the development of Federal Specifications covering these preservatives and several proprietary preservatives. Softwood log grades. Quality classification of logs has been an important feature in all the Laboratory's logging and milling studies. An attempt has been made to grade logs under standard procedure, but no intensive studies of softwood log grades have been made comparable to the effort being devoted to hardwood grades. However, the entire softwood log-buying program of the Northeastern Timber Salvage Administration has been on the basis of grades set up as standard for purchases of hurricane-thrown timber. These grades were built up around grades that had previously been developed by the Laboratory for use in logging and milling studies of New England white pine. In use they have proved satisfactory in New England, and it is probable that with further development they will be made applicable to white pine throughout its region of growth. Paper and pulp.-No specific paper and pulp standards have been promulgated by the Forest Products Laboratory, but indirectly technical data and recommendations obtained at the Laboratory have greatly influenced the purchase and use of the various pulpwoods to yield satisfactory and required pulps for various papers. Pulpwood measuring standards.-The pulpwood industry in the South follows no standard method of measuring pine pulpwood, most of which is delivered in a green condition with the bark on shortly after felling. Pulpwood bolts vary from 48 to 66 inches in length, and the unit of overall measurement varies from 128 to 160 cubic feet. The Forest Products Laboratory, sensing the merit of using weight as a measure for green pulpwood, is engaged in an intensive study of the relation of weight to overall space occupied, and to solid volume of wood. The objective of the study is to obtain facts which it is hoped will reveal the practicability of weighing, Douglas-fir Plywood: Commercial Standard CS45-36," National Bureau of Standards, US Department of Commerce, Washington, D. C., 1939. "Federal Specification CG-451," U. S. Government Printing Office, Washington, D. C., May 1931, 5 cents. Manual of the American Wood Preservers' Association," American Wood Preservers' Association, Washington, D. C., not dated. and will make possible one standard of measurement, a standard no based on scaling judgment but upon weighing scales which are me chanical in operation. A standard of this type has particular meri in that the cost of producing pulpwood varies with weight rathe than with space occupied. House coverage.-The Laboratory prepared for the Federal Hous ing Administration a description of the minimum quality boar suitable for coverage (subfloors and sheathing) in house construc tion. The Federal Housing Administration plans to use the de scription as a basis for judging the suitability of lumber associations grades as described in standard grading rules. The method used in part as specifying acceptable quality by grade name or number ha proved unsatisfactory because of the determination of comparable grades being highly controversial and grades of the same name o number differing widely in quality. Cooperage. Specifications for staves and heading are drawn and administered by the Associated Cooperage Industries of America The Laboratory acts as consultant for the industry furnishing information on the effect of kiln drying, defects, size, and number of staves on the strength and serviceability. Springboards.-The only specifications for springboards are those contained in the National Collegiate Athletic Association's "Swim ming Guide." Those specifications were drawn for one-piece boards although the rules proper do not prohibit the use of laminated boards Considerable trouble has developed in obtaining one-piece boards of satisfactory quality because of size and exacting requirements of use The Laboratory as a result of experiments with laminated boards has furnished manufacturers with specifications for the construction. protection, and mounting of laminated boards. These specifications are used by the industry in the construction of boards, but have not been adopted as standard. There are no recognized standard specifications for either one-piece or laminated boards. Some organizations promulgating standards with which the Forest Products Laboratory cooperates: American Paper and Pulp Association. American Wood Preservers' Association. Associated Cooperage Industries of America. National Hardwood Lumber Association. National Lumber Manufacturers' Association. Northeastern Timber Salvage Administration. Southern Pine Association. Technical Association of the Pulp and Paper Industry. West Coast Lumbermen's Association. United States Department of the Treasury (Procurement Divi sion). United States War Department. |