Departmental Bulletin Paper Effects of HTLH and Kerfing Pretreatement on the Drying Characteristics of Large Square Red Pine Timber

Kang, Chun-Won  ,  Shin, Ik-Hyun  ,  Kang, Ho-Yang  ,  Lee, Yong Hun  ,  Fujimoto, Noboru

60 ( 2 )  , pp.451 - 456 , 2015-09-18 , 九州大学大学院農学研究院
In this study, the effects of two different drying techniques on the properties and characteristics of large square Korean red pine timbers were examined. Wood specimens with a cross section area of 200 × 200mm and length of 3600 mm were subjected to high temperature and low humidity (HTLH) pretreatment followed by air–drying or radio–frequency/vacuum (RF/V) drying, and the result specimens were compared. Theeffect of longitudinal kerfing on drying properties was also examined. The total time of RF/V drying after HTLH pretreatment was 245 h, which led to a decrease in the initialmoisture content (MC) of 83% to a final MC of 5%. RF/V drying was faster than air drying, and the difference in final MC between the internal and external layers of RF/V–dried large square timber was approximately 2%. The slopes of moisture gradients along the thickness directions were very smooth. Our results also indicated that surface checks were effectively prevented by kerfing treatment: no surface checks were observed on kerfed and RF/V–dried timbers. Irrespective of kerfing, very few drying defects of internal checking and twisting were found on RF/V–dried timbers. Case hardening was less than 4% after drying.

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