Color change of veneers treated with some colloidal silica solution systems and their evaluation of weathering resistance

• Published in: MOKUZAI HOZON (Wood Protection) Vol. 31; no. 2; pp. 46 - 56
• Main Authors: GOTO, Takashi, ISHIHARA, Minako, FURUNO, Takeshi
• Format: Journal Article
• Language: English
• Published: JAPAN WOOD PRESERVING ASSOCIATION 25.03.2005
• ISSN: 0287-9255; 1884-0116
• DOI: 10.5990/jwpa.31.46

Veneers of Japanese cedar (Sugi: Cryptomeria japonica) sapwood and Japanese oak (Konara: Quercus serrata) were treated with colloidal silica and boric acid solutions to manufacture woodmineral composed veneers, and the color changes on the veneer surfaces by the treatment were investigated. Then we evaluated the weathering resistance of treated veneers by both leaching procedure and weathering test with a weather meter. Weight percent gain (WPG) for the colloidal silicaboric acid treatment (CB treatment) was larger than that for the treatment with only colloidal silica solution or boric acid solution (C or B treatment). It was found that the CB treatment did not cause any remarkable color change whereas the C or B treatment deteriorated veneer surfaces because of alkalinity or acidity. The fixation ratio of unleached inorganic substances after the leaching procedure was larger in the C or CB treatment than that in the B treatment. Although there was no correlation between the fixation ratio and the color difference (ΔE*), the ΔE value in the CB treatment was the smallest among all the treatments. In the weathering test, it was observed that the ΔE*values varied in the initial stage of the test and trended to increase later. The change in ΔE* for the CB treatment was small in the initial stage, and the ΔE* value in CB-treated sugi ve-neers became smaller than control veneer during the test. Furthermore, the CB treatment prevented the physical erosion of earlywood by the weathering test.