Effect of Steaming on the Colour Change of Softwoods

The heat treatment of softwood (i.e. spruce, pine, fir, and larch) may result in significant colour changes. During this study Scots pine and spruce samples were steamed and analysed for their altered hue and lightness. Treatments included: 0 to 22 days of steaming time at a temperature range of 70 to 100°C. The outcome included a variety of colours between the initial hues and brownish tint. These new colours are similar to that of aged furniture and indoor wooden structures. Consequently, properly steamed softwood may be used to repair historical artefacts and relic furniture. Besides restoration, steamed stocks are excellent sources for manufacture of periodical furniture, where the aged appearance has aesthetical value. Results however, indicated that steaming at a temperature above 90 ̊C has a bleaching effect, i.e. the coloured chemical components formed by moderate steaming may be removed. Furthermore, we observed a linear correlation between lightness and colour hue at all steaming times and temperatures.