Steam-injection pressing of isocyanate-bonded aspen flakeboards, latitudes and limitations

Injection of steam into a flakeboard mat during pressing significantly reduces press times. One-half-inch-thick 0.640 specific gravity (SG) isocyanate-bonded aspen flakeboard can be cured in 60 seconds by injecting 99 Btu's of steam energy per pound (Btu/lb) of board. Press time may be reduced to 40 seconds when energy consumption is increased to 177 Btu/lb of board. Two-inch-thick 0.640 SG board can be pressed in 201 seconds with 185 Btu/lb. Blister formation in high-density thin boards and temperature variation in low-density thick boards were compensated for with press cycles individually suited for each combination of board thickness and SG.