Effect of Hot-pressing on Surface Drying-set in Sugi Columns with Pith

We investigated the effect of hot-pressing as a pre-treatment for prevention of surface checks in sugi (Cryptomeria japonica D.Don) columns with pith. In order to find an effective condition for prevention of surface checks and to obtain fundamental knowledge of hot-pressing surface treatments, we particularly investigated the effect of hot-pressing surface treatment for formation of drying set in the sugi column surface. Hot plate temperature was set at three levels: 150, 180 and 210°C. Press time was set at two levels: 30 and 60 min. As a result, the intensity and the depth of drying set increased with hot plate temperature and press time. Drying set was formed to a maximum depth of 7 mm. On the other hand, moisture content decreased to less than 10% at the specimen surface on 180°C, 60 min and 210°C, 60 min treatment conditions, but the moisture content increased at the inside. It was suggested that the drying set which was formed in the sugi column surface by the hot-pressing surface treatment in a short time and its intensity are about the same as with the conventional high temperature drying method.