Range of color changes of beech wood in the steaming process

Changes in color were evaluated for beech wood Fagus sylvatica L., caused by a steaming process using either a mixture of saturated steam and air or saturated water steam in the temperature range: t = 95 °C to 125 °C for a duration of T = 3 h to 12 h. The initially light white-gray color of beech wood with a yellow tint darkened during the thermal treatment process. It changed to a pale pink-brown and then to dark brown color. According to the visible changes in the color of beech wood obtained by the thermal treatment process with the human eye, , a color scale was proposed as a means to categorize the severity of treatment. The color ranged from a pale pink-brown color to a dark brown-red color depending on the value of the total color difference ∆E*.