Properties of drying sugi [Cryptomeria japonica] structural timbers by boiling in paraffin liquid
2001
Matsuoka, Y. (Kochi-ken. Forest Experiment Station, Tosayamada (Japan)) | Noji, K. | Masaoka, H. | Mizutani, T. | Yanagida, E. | Kanagawa, Y.
Boxed heart squared timbers of Sugi (Cryptomeria japonica D.Don) were dried in high temperature paraffin liquid, and then the drying properties were examined. Boxed heart squared timbers were rapidly dried in high temperature paraffin oil bath of 150 deg C from an average moisture content of 65% to 18% in 20 hours. Distribution of the moisture content along longitudinal direction at the end of drying process was almost even. But that of the moisture content along cross direction was uneven, i.e. the moisture content of surface was the lowest and the of center was comparatively lower than that of the others except surface. Distribution of the timber temperature along longitudinal direction was almost even from the beginning of drying to the end. On the other hand that of the temperature along cross direction was uneven i.e. that was higher at the depth of 20mm than at that of 45 or 55mm. Surface checks was found in several timbers and average width and length of the checks in all the timbers was respectively 2mm, 86cm. Internal checks around the pith was found to all the timbers because of the high water vapor pressure. The wood color across to the grain was discolored and that of the end-grain partially turned into black. The difference of the degree of discoloration couldn't be found between the treating temperatures of 120 and 150 deg C. Not only for drying but also for preservation the research on boiling in paraffin bath is expected to be worth continuing.
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