<Note>Some Aspects on Resistance of Acetylated Wood against Biodeterioration

Abstract

Resistance of acetylated wood against biodeterioration was investigated at different levels of acetylation. Spruce (Picea jezoencis) wood veneers were treated with uncatalyzed acetic anhydride for different lengths of time and exposed to each two species of wood-rotting fungi and subterranean termites. The protective effect by acetylation was clearly observed for all test organisms but varying with decay type or species used. For a brown-rot fungus Tyromyces palustris, the weight loss reached nill at 18 WPG (weight percent gain) of acetylation after the rapid decrease from 10 to 15 WPG. For a white-rot fungus Coriolus versicolor, it decreased at higher rate with degree of acetylation and was not counted at just 6 WPG. The attack by termite Reticulitermes speratus was almost nill at the highest acetylation of 18 WPG with its rapid decline from 13 WPG. Perfect inhibition was unsuccessful even at 18 WPG for more virulent species Coptotermes formosanus but the similar decline of attack was confirmed, too. A large number of bore-holes were produced by fungal attack in the cell walls of acetylated wood below the threshold value for biological resistance. Existence of sporadic erosion in the cell walls was characterized as the limited attack of acetylated wood by fungi.