0023-6152

AA00697606

1543408

査読無

0023-6152

AA00697606

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. The effect 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 initial moisture 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.