Effect of Heat Upon the Dimensional Stabilization of Wood

HEATING WOOD TO TEMPERATURES considerably above normal seasoning temperatures is the oldest, simplest, and cheapest means now known for stabilizing the dimensions of wood, but the treatment, unfortunately, embrittles the wood significantly (8, 9, 13). Dimensional stabilization of wood with heat has been previously shown to be dependent upon a combination of temperature and time. The time required to attain a given antishrink efficiency (dimension change of the control minus the dimension change of a matched heated specimen divided by the dimension change of the control between the oven-dry and the water-soaked conditions, or between two different relative humidities, expressed in percent) increases in a logarithmic fashion with a decrease in temperature (8). An appreciable weight loss accompanies dimensional stabilization. The loss is greater per unit time when the wood has free acess to air than when heated beneath the surface of a molten metal (6, 8). Dimensional stabilization by heat is accompanied by a loss of water of constitution of the wood. This fact, coupled with limited data showing that dry heat is more effective than moist heat, was the basis for the hypothesis that stabilization by heat, like the reaction of wood with formaldehyde ( 12), is a cross-linking reaction (9). The postulated cross linking was pictured as an oxygen linkage (that is, an ether) formed by water splitting off between two