Press Drying Nine Species of Wood

Press drying was used on eight hardwoods and one softwood to explore the potential of this drying method in utilizing low-grade logs for products such as paneling and pallets. The results showed that the material 1/2 inch thick could be dried to 4 to 6 percent moisture content in 25 to 75 minutes. Material 1 inch thick could be dried to the same moisture content in 100 to 200 minutes. Severe checking and honeycombing occurred in the heartwood of refractory species. The sapwood of all species and the heartwood of the less refractory species dried without serious degrade. Species that press dried without severe drying degrade had properties similar to those of kiln-dried material. Cyclic shrinking and swelling indicated that the press-dried material was 30 to 60 percent more stable in width dimension than the kiln-dried material, but was, in general, 10 to 80 percent less stable in thickness dimension. Drying material for these tests was selected from 39 logs, 10 feet long, representing five separate trees each from the following species: ash, red oak, white oak, post oak, hickory, sweetgum, plus two logs each of cypress and rock elm. The drying experiments were conducted in a steam-heated single-opening 2- by 8-foot hot press. Specimens from each log were press dried at a platen temperature of 345?F. and a pressure of 50 pounds until a thermocouple at the midthickness of the specimen indicated a temperature of 20?F. below the platen temperature. Toughness, hardness, and abrasion resistance were the three strength properties evaluated. Additional tests were made for gluability, machinability finishing, and sorption behavior.

You must be logged in to download any documents. Please login (login accounts are free) or learn how to Become a Member