Commercial Hardwood Veneer Drying Variables and Laboratory Correlation

Three main types of hardwood veneer driers — continuous conveyor, hot plate press, and high restraint roller drier — are described. Buckled veneer is caused by the uneven drying effects of tension wood, uneven end drying (casehardening or lateral set) or uneven side drying (longitudinal set). Normal casehardening is controlled by a small amount of restraint (5 pounds per square foot) while mechanical casehardening, induced particularly in high restraint driers, cannot adequately be corrected. Black markings from veneer contact with steel conveyor components, checkerboard discoloration from uneven air circulation, and splits and checks from poorly distributed restraint in the hot plate press are present but of lesser significance. Species are identified with respect to dryability and important drying defects. Future research should consider such factors as wet and dry bulb temperatures, air circulation rate and distribution, and amount of restraint present.

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