Effect of smoke heating on moisture content, surface checking, and dynamic Young's modulus of sugi (Cryptomeria japonica) boxed heart timber
2001
Ishiguri, F. (Utsunomiya Univ. (Japan). Coll. of Agriculture) | Andoh, M. | Yokota, S. | Yoshizawa, N.
The effect of smoke heating on moisture content, surface checking, and dynamic Young's modulus of sugi (Cryptomeria japonica D. Don) boxed heart timber was investigated. Five different smoke-heating treatments were used : A (65 =+- 5 deg C, 4 days), B (75 =+- 5 deg C, 1 day), C (75 =+- 5 deg C, 2 days), D (85 =+- 5 deg C, 1 day), and E (85 =+- 5 deg C, 2 days). After smoke heating, moisture content, frequency of surface checks, and dynamic Young's modulus were determined. The moisture content of boxed heart timbers was decreased by all treatments. However, boxed heart timbers with high moisture content before smoke heating showed high moisture content ranges in a timber even after smoke heating, suggesting that the moisture content range in a timber depends on initial moisture content, especially on the high moisture content in the center of heartwood. Many surface checks frequently occurred in boxed heart timbers after treatments D and E, whereas severe surface checking was absent after treatments A, B, and C. High temperature and low humidity during the smoke-heating treatments may have caused the increased frequency of surface checks in the boxed heart timber. On the other hand, in all of the treatments used here, significant decreases in dynamic Young's modulus were not observed. The results obtained in the present study suggested that in the smoke heating of boxed heart timber, control of humidity in the treatment chamber during smoke heating is needed to decrease both of moisture content and damage.
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