Colour changes by thermal treatments are a good alternative to increase wood quality, especially for non-structural uses. In this study, rose gum (Eucalyptus grandis) and Sydney blue gum (Eucalyptus saligna) woods from Southern Brazil were thermally treated under different conditions (steam pre-treatment in an autoclave at 127 °C for 1 hour and heat treatment in an oven at 180, 200, 200 and 240 °C for 4 hours) and colour changes were investigated using CIEL*a*b* technique. The main findings show that thermal treatments resulted in darkening of the wood, which was more intense at high temperatures. Colour difference after two-step steam-heat treatments was higher than 45 for both species. In general, the influence of the steam pre-treatment was more visible in lower temperatures. Lightness (L*) was the parameter that best described the colorimetric behaviour of rose gum and Sydney blue gum woods. In conclusion, thermal treatments are a great method to improve the market value of wood, especially for aesthetic uses, but it requires a control of process conditions.
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机译:热处理引起的颜色变化是提高木材质量的好选择,特别是对于非结构性用途。在这项研究中,对巴西南部的玫瑰胶(Eucalyptus grandis)和悉尼蓝胶(Eucalyptus saligna)木材在不同条件下进行了热处理(在127°C的高压釜中蒸汽预处理1小时,然后在70°C的烤箱中热处理)在180、200、200和240°C的温度下放置4小时),并使用CIEL * a * b *技术研究了颜色变化。主要发现表明,热处理导致木材变暗,在高温下强度更大。两个物种经过两步蒸汽热处理后的色差均高于45。通常,蒸汽预处理的影响在较低温度下更明显。亮度(L *)是最能描述玫瑰胶和悉尼蓝胶木材比色行为的参数。总之,热处理是一种提高木材市场价值的好方法,特别是在美学用途上,但它需要控制工艺条件。
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