A Novel Rapid Artificial Drying Schedule for Japanese Cedar Boards Retaining Natural Durability

Abstract

The objective of this study was to develop a novel and rapid artificial drying schedule for a boards of Japanese cedar (Cryptomeria japonica). Boards of green wood were dried to a moisture content of 15% under 9 artificial drying conditions with a combination of three dry-bulb temperatures (50 degrees C, 70 degrees C and 90 degrees C) and three wet-bulb depressions (5 degrees C, 10 degrees C and 20 degrees C). We found that the condition of 90 degrees C dry-bulb temperature and 20 degrees C wet-bulb depression produced dried boards in the shortest period. The boards indicated no significant color change for practical use. In addition, the dried boards showed durability against brown-rot fungi Fomitopsis palustris and subterranean termites Coptotermes formosanus comparable to naturally dried heartwood boards. The relative contents of cadinols demonstrated negative correlation with weight loss in decay tests. These results may lead to improvement of drying schedules for Japanese cedar boards while retaining natural durability.