650 



Yearbook of Agriculture 1949 



rinated phenols would have special 

 value as wood preservatives. 



To broaden the source of raw ma- 

 terials for the pulp and paper indus- 

 try, such species as the southern yel- 

 low pines and various hardwoods have 

 been made usable by means of new 

 pulping processes. Those species sup- 

 plement the dwindling supplies of 

 spruce and balsam that have been most 

 favored by the industry. Research has 

 opened the way to such new materials 

 and processes. One entirely new proc- 

 ess, semichemical pulping, was de- 

 veloped and first placed on a practical 

 basis by the Laboratory in about 1924. 

 This process, that is especially adapted 

 to hardwoods, yields about 50 percent 

 more pulp, with less costly plants, than 

 some of the older processes. By it, near- 

 ly 500,000 tons of semichemical pulp 

 are now being produced annually, and 

 the amount is increasing. More recent 

 investigations of its possibilities for the 

 conversion of low-quality wood and 

 wood residues are leading to increased 

 utilization of those materials for many 

 kinds of pulp and paper. 



The painting of wood has been 

 placed on a more scientific basis. The 

 greater part of the knowledge on which 

 this improvement is based has come 

 from research and exposure tests at the 

 Laboratory on the paint-holding ca- 

 pacity of American woods. As a result, 

 the usefulness of paints for their ef- 

 fect on the appearance of woods (as 

 distinguished from their protective 

 properties) is now better understood. 

 The common woods have been dis- 

 tinctly classified as to their paintability, 

 and the causes of various types of paint 

 failure have been determined. The dis- 

 advantages of using unlike paints in 

 succession on the same surface, as in 

 repainting, have become clear, and the 

 use of special primers and control of 

 two-coat work developed. Millions of 

 dollars were saved by the armed forces 

 during the war by applying the findings 

 to the painting of military buildings. 



It has been known for years that 

 cellulose can be transformed into 

 sugars. This knowledge was first ap- 



plied in this country during the First 

 World War and later more efficiently 

 utilized by the Germans. In the last few 

 years, the commercial possibilities of 

 sugar production from wood have been 

 developed further by reducing the 

 treating time to one-half of that need- 

 ed by the Germans and increasing the 

 yield to about one-half ton of sugar 

 from a ton of wood. These sugars show 

 promise as molasses for animal feed 

 and as the raw material for producing 

 alcohol, yeast, and other products. 



Although the Laboratory staff has 

 been occupied largely by major re- 

 search problems of the kind named, 

 many minor problems, such as deal 

 with a single type of use for a single 

 species, have not been neglected. Some 

 years ago, for example, certain western 

 railroads were about to reject Engel- 

 mann spruce as a material for cross 

 ties, although it was at hand in their 

 territory, because it was difficult to 

 treat with preservatives. The Labora- 

 tory found a means of reducing the 

 difficulty and made possible the con- 

 tinued use of this wood. Similarly, a 

 way was devised to cut southern water 

 oak into veneer satisfactory for ply- 

 wood for fruit and vegetable contain- 

 ers, by which a market was provided 

 for this previously neglected species. 

 Since then, one operator produced in 

 3 months a half million square feet of 

 water oak plywood. 



New wood products developed in re- 

 cent years include moisture-resistant, 

 dimensionally stable, resin-treated im- 

 preg and compreg used for aircraft 

 propellers, knife handles, and for ship 

 decking; the high-strength laminated 

 paper plastic, papreg, used for table 

 tops, truck floors, and ammunition 

 boxes; and the dimensionally stable, 

 resin-free, compressed wood, staypak, 

 useful for textile spinning reels, shut- 

 tles, picker sticks, and mine guides. 

 New uses for wood have been suggested 

 by the unusual moisture resistance, the 

 freedom from shrinking and swelling, 

 the hardness, and the beautiful ap- 

 pearance of some of these modified 

 woods, although their applications to 



