Practical development of hot blow vacuum drying kiln, 2: Kiln drying of cylindrical wood used for Japanese drums
2006
Myojin, M.(Yasujima Co. Ltd., Kanazawa (Japan)) | ; Yasujima, M. | ; Hayashi, K.
In this study, we applied the newly developed drying method with a combination of hot blow and vacuum in order to kiln-dry the precious hardwood materials used for making Japanese drums. Three green and one air-dried half-finished cylindrical keyaki materials (Zelkova serrata) were offered to the drying experiment. By referring the existent equilibrium moisture content (EMC) schedule of conventional drying, we examined the more proper drying condition for the drum materials where even small defects would never be allowed. Dry bulb temperature was kept lower than boiling point of water in the early stage of drying from green to fiber saturation point (FSP), and then dry bulb temperature was elevated to the higher level than boiling point. Obtained results were as follows; (1) No crack occurred on the half-finished cylindrical drum materials. (2) Drying time under FSP was able to be reduced to 1/3 compared with conventional steam-heat drying without any defects by elevating dry bulb temperature higher than boiling point of water in the late drying stage under 25 % moisture content. (3) Drying cost seemed to be not so high even if drying time is rather long because hot water can be used instead of steam in this drying method.
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