Correlation Between Hue-angle and Colour Lightness of Steamed Black Locust Wood

Abstract

Black locust (Robinia pseudoacacia L.) wood was steamed at wide range of temperature (75-130°C) applying long (22 days) steaming time. The colour change was monitored by CIE L*a*b* and L*h*c* colour co-ordinate systems. A wide range of colours from greenish yellow up to chocolate brown were created by steaming in function of the steaming time and temperature. In spite of this wide colour range a good linear correlation was found between the lightness and the colour hue. This linearity had little distortion only above 100°C at a long steaming time. Accordingly, this linear correlation gives the possibility to follow the colour change during steaming by measuring only the lightness.