Japanese cedar (Cryptomeria Japonica D. Don) 110 110 1000-mm green boxed-heart timbers were dried under high temperature (110-140C) and high humidity (0.01-0.24 MPa gauge pressure) conditions until the weight remained unchanged. Then strength properties were examined. Wood became brittle because of the high temperature and high humidity treatment. We hypothesize that the wood was seriously damaged by hydrolysis because of the long treatment time used in this study and that the large cross-sectional area and high set gauge pressure lengthened the time of water loss from the wood. We considered viscosity and plasticity, rather than elasticity, to be the main factors that contributed to the decrease of work for rupture
