STEAM OR HEAT FIXATION OF COMPRESSED WOOD

Dimensional stability can be improved by either steaming or heating wo od while the wood is in a compressed state. This study investigated th e effect of steam or heat on fixation of compression set and the effec t of these treatments on hardness, mechanical properties, and color of compressed and uncompressed wood specimens. To determine the effect o f steaming before and after compression set, one group of wood specime ns was steamed and then compressed, and another group was compressed a nd then steamed. Simple boiling and cyclic swelling tests were used to evaluate recovery of compression set. Hardness of compressed specimen s was measured by the Brinell test. A two-point bending test on noncom pressed specimens was used to calculate moduli of elasticity and ruptu re. A L-a-b color system was used to determine color changes. Compress ed wood steamed for 1 min at 200 C or 8 min at 180 C showed no recover y of set, large increases in hardness, minimum decreases in mechanical properties, and slight darkening. We conclude that almost complete fi xation of compression set in wood can be achieved by steaming compress ed wood.