ABSTRACT

The whitening of wood adjacent to metal components is commonly observed in historic Japanese architecture. A field investigation of the Old Iwasaki-ke Suehiro-bettei Villa led the researchers to believe that this phenomenon is related to significant fine particles of copper/zinc oxalate in wood tissues. In this study, aimed at verifying the effects of Cu(II)/Zn(II) ions on wood, a model experiment was carried out with wood powders of Sugi (Cryptomeria japonica) and Keyaki (Zelkova serrata), with different levels of Cu(II)/Zn(II) ion contents (percentage of dry weight: 0.00%, 0.05%, 0.50%, 2.50%). The samples were exposed under the conditions of 60°C and a relative humidity (RH) of 90%. The degradation of the exposed samples was evaluated every 30 days using ion chromatography (IC) analysis for oxalate ion concentration, high-performance liquid chromatography (HPLC) analysis for monosaccharide concentrations with water extract samples prepared from the exposed samples, and Fourier transform infrared attenuated total reflection (FTIR-ATR) analysis to track spectral changes of the exposed samples. After 90 days of exposure, a significant detection of oxalate ions and monosaccharide content was confirmed in the samples with metal content, especially in the samples with 2.50% Cu content. The presence of oxalate ions was attributed to metal-promoted degradation of polysaccharide constituents in the wood.

摘要

在历史悠久的日本建筑中，通常会观察到与金属部件相邻的木材变白。对旧 Iwasaki-ke Suehiro-bettei Villa 的实地调查使研究人员相信，这种现象与木材组织中大量的草酸铜/锌细颗粒有关。本研究为验证Cu(II)/Zn(II)离子对木材的影响，采用杉木( Cryptomeria japonica )和榉木( Zelkova s​​errata )的木粉进行了模型试验。)，具有不同水平的 Cu(II)/Zn(II) 离子含量（干重百分比：0.00%、0.05%、0.50%、2.50%）。样品暴露在 60°C 和 90% 相对湿度 (RH) 的条件下。每 30 天使用离子色谱 (IC) 分析草酸盐离子浓度、高效液相色谱 (HPLC) 分析从暴露样品制备的水提取物样品的单糖浓度评估暴露样品的降解情况，以及傅里叶变换红外衰减全反射 (FTIR-ATR) 分析以跟踪暴露样品的光谱变化。暴露 90 天后，在含有金属含量的样品中，特别是在含有 2.50% 铜含量的样品中，证实了草酸根离子和单糖含量的显着检测。