Surface-check variation in boxed-heart square timber of sugi (Cryptomeria japonica) cultivars dried by the conventional kiln drying

Abstract

To investigate the factors affecting the surfacecheck variation in boxed-heart square timber of sugi (Cryptomeria japonica), surface checks formed by the conventional kiln drying were compared for two stem heights of five cultivars with different wood properties. The total length and average length of the surface checks were greater at the upper part of the stems for all the cultivars. This might be caused by more sapwood at the upper part of the stem, and large drying stresses between the outer sapwood and the inner heartwood. The cultivars, in which tangential shrinkage was large owing to small microfibril angle, formed longer surface checks and smaller bow. There was a positive relationship between surface-check length and tangential shrinkage. The heartwood percentage and tangential shrinkage were thought to be important factors affecting the surface-check variation in sugi boxedheart square timber.

Review on Wood Deformation and Cracking during Moisture Loss

“…Specifically, the length of the cracks displayed a direct proportionality to the radial shrinkage. Moreover, internal cracking near the pith was found to be relatively severe, largely due to the impact of radial shrinkage [ 64 , 65 ]. Phonetip et al compared two internal check measurement methods for wood drying quality assessment [ 66 ].…”

Three-dimensional numerical analysis of water transfer in wood: determination of an expression for the effective mass diffusivity

“…One of the methods used for wood drying employs hot air (Yamashita et al 2012;Watanabe et al 2012) but, according to Plumb et al (1985) and many other researchers, the experience has shown that serious cracking, warping, and fiber collapse occur if the wood is dried too fast. On the other hand, Plumb et al (1985) observed that if the drying operation lasts too long, excessive energy and time costs decrease productivity of the plant.…”