Treesearch

The mechanical behavior of a flexible epoxy-resin adhesive system was observed in joints of plywood to lumber. The joints were subjected to internal swelling stresses caused by an increase in moisture content. Previous experimental work at the U.S. Forest Products Laboratory has shown that this adhesive system acts as a strain-absorbing cushion and thus has a significant stress-relieving effect in the joint. An attempt was made to use this adhesive as a calibrated tool for measuring shear strain as a function of lumber size, lumber specific gravity, and glueline thickness in a plywood-to-lu...

A new system of wood-frame house construction has been developed which combines increased use of low-grade wood, prefinished components, and rapid field assembly methods without much divergence from conventional construction. Laboratory evaluations of the components of the Nu-frame system indicated that; (a) 4-foot spacing of the W-trusses tested provides a safety factor of three over design load, (b) the wall framing system with 4-footspacing of double 2- by 4-inch studs (Nu-frame) is a reasonable method of construction, (c) the use of a l/2-inch fiber board filler between studs (Insul-2)...

The owner of a small quantity of green lumber or logs is often confronted with seasoning it to a state of dryness suitable for use in furniture, wood carving, or other handiwork. He cannot follow the practice of commercial mills, which employ dry kilns for the purpose. because kilns are too costly. On the other hand, air seasoning outdoors usually does not dry lumber sufficiently for such uses, although it is sufficient for structures that will be used outdoors. Green lumber can be seasoned to the necessary dryness for the purpose by combining outdoor air seasoning with subsequent further...

Physical and mechanical properties were determined for saligna eucalyptus (Eucalyptus saligna, Smith) grown in Hawaii. In comparison with wood of the same species grown in Australia, saligna eucalyptus grown in Hawaii was lower in density, shrinkage, and compressive strength parallel to grain; it was about equal in strength in bending and shear; and it was stiffer. Compared to commercially important Mainland species, saligna eucalyptus grown in Hawaii is considered exceptionally stiff and the green wood is stronger than average for its density: however, strength of air- dry wood and...

The Forest Products Laboratory has developed a laminated diving board that has shown excellent performance characteristics. This board has given long, economical service under the severe moisture hazards and heavy service conditions such as found at public swimming places. The adhesive used is of the fully waterproof synthetic-resin type, which requires no protection from moisture. The board is made from narrow strips of seasoned lumber and is fully equivalent to the premium-quality one-piece boards made from selected wide and thick stock.

A laboratory procedure is outlined that incorporates techniques found to promote soft rot by several fungi. This procedure employs either an agar or a soil substrate. Also presented are the principal findings of experiments underlying the procedure. Results of tests conducted according to the suggested procedure are illustrated. The overall decay resistance of the softwoods typically was greater than that of hardwoods. The levels of decay in softwoods, however, were substantially higher than previously obtained. There was a tendency for decay in soil to he somewhat greater than on agar;...

“Pacific madrone (Arbutus menziesii Pursh) is a moderate-sized hardwood tree found in the Pacific coastal country from British Columbia to southern California. In California it also grows in the western Sierra Mountains below 4,000 feet elevation. The tree is also known as madrono and madrona. It is locally used for fuelwood, fence posts, charcoal, and to a minor extent for lumber and veneer. The latter uses are limited because of the tendency of the tree to grow with poor form except in dense stands. The tree attains a diameter of 2 to 4 feet (2) 2 and a height of about 80 feet on good...

This report gives information on the preparation of wood fuel from wood residues and other wood raw materials. Types of wood fuel discussed are cordwood, stovewood, slabwood, kindling, chips, hogged fuel, sawdust and shavings, bark, charcoal, alcohol, and briquets. Related information is given on types of machinery for preparing wood fuel and on possible markets for its sale.

The purpose of this meeting was to bring together about 30 representatives of the various forest products industries and a few affiliated research and educational institutions to discuss and define industry needs for nondestructive testing. The necessity for such a meeting was made clear in the Symposium on Nondestructive Testing of Wood held at this Laboratory in October 1963.1 The meeting was a direct result of the recommendation made at the close of that Symposium, pointing out that effective development of nondestructive testing within the forest products industries is dependent on...

With all the favorable properties that contribute to its wide use in farming, wood nevertheless needs to be used intelligently, and protected from certain natural enemies. For example, while some species of wood are naturally resistant to attack by decay fungi and harmful insects, most species lack adequate resistance when exposed to attack, This is not serious when wood can be kept dry and away from contact with the ground. However, for such farm uses as fencing, poles, bridges, culverts, irrigation structures, silos, storage sheds, barns, and some types of vehicles, wood must be used in...