Effect of steam injection re-drying of Japanese cedar on preservative leaching after passive impregnation

Abstract

This study investigated the effects of steam injection re-drying on the leaching of copper azole type B (CAz-B) preservative from green and kiln dried Japanese cedar (Cryptomeria japonica (L.f.) D.Don) lumber treated by the passive impregnation method. The leaching and fungal treatments were performed according to the JIS Z 2101-1994 standard. Sixteen hours of steam injection re-drying reduced the moisture content from 152 to 82% and 195 to 55% for initially green and dry lumber, respectively. Preservative retention was higher in the dry lumber (5.21 kg/m³) compared with the green (4.66 kg/m³), however, leaching percent was similar for both types. Preservative leaching and mass loss due to fungal attack were significantly lower in the lumber re-dried by steam injection compared with air dried. Thus, steam injection re-drying after passive impregnation treatment could be a step toward fixing CAz-B preservative in Japanese cedar lumber.

Keywords:

• Laser incising
• leaching
• mass loss
• air drying
• copper azole

Acknowledgements

The authors are indebted to the Japan Society for Promotion of Science (JSPS) for providing financial support.