Effect of pressure steaming on twist and stability of radiata pine lumber

Three matched series of 2400- by 100- by 40-mm radiata pine lumber were dried at 140?C with one series being final steamed at 100?C, atmospheric pressure, and the other two under pressure at 150?C for 0.25 and 0.7 hour on setpoint, respectively. Twist and moisture content (MC) of the three series were assessed before exposure to two cycles of alternate high and low humidity. After each stage of cycling, twist and MC were reassessed. Compared to normal steaming at 100?C, the pressure steaming at 150?C reduced twist by over 25 percent, but there was no additional twist reduction from extending the pressure steaming duration from 0.25 hour to 0.7 hour. Subsequent humidity cycling showed that the reduction in twist was permanent for pressure-steamed material, whereas material steamed at normal conditions exhibited a trend for increased twist with each humidity cycle.

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