The Impregnation of Wood to Impart Resistance to Alkali and Acid

A process was developed for impregnating wood with furfuryl alcohol resins to make wood resistant to both acid and alkali. Effects of impregnation on wood properties are discussed and uses listed for furfuryl alcohol resin-treated wood. After machining to the desired shape, the wood to be treated is impregnated by conventional wood-preserving techniques with a treating solution consisting of a catalyst dissolved in monomeric furfuryl alcohol. When the treated wood is heated in an oven or dry kiln the catalyst causes polymerization of the furfuryl alcohol in the wood to a hard, chemically-resistant resin. Any species of wood may be used that allows penetration of the treating solution at 150 psi. The wood so impregnated becomes dark in color. The hardness of the wood and crushing stress perpendicular to the grain are increased markedly by the treatment. Impact strength is decreased. Furfuryl alcohol swells wood more than water does, and the greatest part of this swelling is permanently retained in the cured resin-impregnated wood. Additional swelling, however, still takes place upon exposure of the treated wood to high humidity or saturation in water. The major effects of alkali upon wood appear to be delignification, removal of hemicelluloses, and the accompanying shrinkage. The furfuryl alcohol resin-treated wood shows improved resistance to decay.

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