The Forest Products Laboratory 



649 



intelligent use and by reliable data on 

 the growth, structure, and strength 

 properties of these species. More than 

 a million tests have provided data on 

 which to base sound working stresses 

 and establish structural grades for use 

 in design and for inclusion in building 

 codes. The test methods developed at 

 the Laboratory were recognized in 

 1927 by the American Society for Test- 

 ing Materials and have been adopted 

 in many foreign countries. 



More than 175 native woods, as 

 well as some foreign species, have been 

 tested for strength. Companion data 

 needed by design engineers have been 

 obtained on such types of fastenings as 

 nails, screws, and connectors, and 

 studies have been made to determine 

 the effect of loading conditions, defects, 

 and moisture on strength. New con- 

 structions, such as plywood and sand- 

 wich materials, have been investigated 

 and the strength of these complex 

 materials determined both by actual 

 tests and by means of mathematical 

 analyses that short-cut laborious and 

 time-consuming tests of individual 

 specimens. This information has been 

 depended on widely by the wood- 

 using industries in the selection of ma- 

 terial and species for specific purposes, 

 such as poles, structural timbers, air- 

 craft, boxes, boats, and housing. 



The development of Federal specifi- 

 cations for wood and fiberboard boxes 

 has been almost entirely a responsi- 

 bility of the Laboratory for the past 

 30 years. Although these specifications 

 were designed for Government use, 

 they have been widely adopted as the 

 basis for improved commercial con- 

 tainers that have greatly reduced ship- 

 ping costs. It has been estimated that 

 the research on containers has effected 

 annual peacetime savings of about 40 

 million dollars through reduced dam- 

 age to merchandise, use of thinner lum- 

 ber, and containers of lower weight 

 and less volume. 



The satisfactory service rendered by 

 many wood products depends on the 

 glue used as a binder for their parts. 

 Skill in the gluing of wood has been 



improving for centuries, with the most 

 striking advances taking place within 

 recent years. Accepted standards for 

 measuring the strength and durability 

 of glue joints have been important in 

 this development. To provide those 

 standards, we devised two glue-test 

 joints, a tension- test joint for plywood 

 and a block-shear-test joint for heavier 

 laminated woods, and standard meth- 

 ods of testing them that have been 

 accepted by glue makers and users. 

 The strength of new glues and their 

 resistance to moisture, heat, and decay 

 have been measured by their perform- 

 ance in these standard- type joints, both 

 newly made and after exposure to 

 severe conditions of service. 



DURING THE SECOND WORLD WAR, 

 more than 100 new commercial resin 

 glues were tested for the Army and the 

 Navy. The tests assisted the manufac- 

 turers in the elimination of poor glues 

 and the rapid development of the more 

 effective glues. These adhesives have 

 made plywood and laminated wood 

 joints highly durable for outdoor use. 

 They have made practical, also, the 

 gluing of wood to metal, plastics, and 

 other materials that require adhesive 

 properties not possessed by glues pre- 

 viously used for joining wood to wood. 



In the field of wood preservation, 

 the work here has contributed substan- 

 tially to the development and to the 

 standardization of preservatives and 

 treating methods for a wide range of 

 wood uses in which durability is im- 

 portant. An example is the work 

 on pentachlorophenol, an oil-soluble 

 chemical, which has come into increas- 

 ing use as a wood preservative until 

 now millions of pounds of it are pro- 

 duced annually for this purpose. One 

 of its common applications is quick 

 treatment of window sash to impart 

 decay resistance. The development of 

 this material as a wood preservative 

 dates back to 1930, when we suggested 

 to chemical manufacturers that, on the 

 basis of observations and the theoreti- 

 cal poisoning effect of certain benzene 

 compounds on decay organisms, chlo- 



