Colour homogenisation of hardwood species by steaming

Abstract

For colour homogenisation three hardwood species, black locust (Robinia pseudoacacia L.), beech (Fagus silvatica L.) and Turkey oak (Quercus cerris L.) were investigated. Steaming was applied to change the colour. Steaming parameters (steaming time and temperature) were varied to find the optimum of treatment. The results are given in the CIE L*, a*, b* colour co-ordinate system. Black locust wood was most sensitive to the steaming temperature. With rising temperature, the colour change was faster and less time was needed for homogenisation. The behaviour of the other two wood species was different from black locust but similar to each other. Below 95°C homogenisation was insensible to temperature and within one day the colour change stopped. Above 95°C the colour change was continuous but without further colour homogenisation. The optimum homogenisation time was found about 12 hours at 80-95°C temperature range and 6 hours at 110°C for Turkey oak, and 18 hours at any temperature for beech.