Heat Modification of Wood: Chemical Properties and Resistance to Mold and Decay Fungi

The resistance of heat-modified sugi ( Cryptomeria japonica D.) sapwood against mold and decay fungi was evaluated under laboratory conditions. Wood specimens were subjected to heat treatment at 180°C for 2 and 4 hours and at 220°C for 2 hours. Changes in lignin and polysaccharide weight percent composition, solubility, and pH of heat-modified specimens were determined. Treatment at 220°C for 2 hours decreased wood polysaccharide content. Heat treatment slightly increased resistance against Rhizopus javanicus and Gliocladium ( Trichoderma ) virens, but not against Aspergillus niger . The highest temperature used increased resistance to decay by the white-rot fungus Trametes versicolor, but mass losses with the brown-rot fungus Fomitopsis palustris were higher than those with T. versicolor .