Wood Quality of Sugi (Cryptomeria japonica D. Don) Boxed Heart Square Timbers Treated by Smoke-Heating System with Far-Infrared Radiation

On Moisture Content, Surface Check, Dynamic Young's Modulus

Abstract

Boxed heart square timbers of sugi (Cryptomeria japonica D. Don) were treated by smoke-heating system with increased far-infrared radiation for about 50 hours at a temperature inside the square timbers of 70°C-80°C. After smoke-heat treatment (SHT), wood qualities (moisture content, surface check, dynamic Young's modulus) were examined. Average moisture contents of boxed heart square timbers were largely decreased by SHT, but moisture contents near the pith still remained high. No surface checks occurred in 29 specimens (24.8%) of 117 square timbers smoke-heated. In addition, decrease of dynamic Young's modulus by SHT was not recognized. The results obtained indicate that SHT has effect on pre-drying of square timbers, without any damages, followed by kiln drying.