Color modification and homogenization of sugi wood (Cryptomeria japonica) by steaming

Abstract

Abstract. Tolvaj L, Banadics EA, Tsuchikawa S, Mitsui K, Preklet E. 2019. Color modification and homogenization of sugi wood (Cryptomeria japonica) by steaming. Asian J For 3: 20-24. Color modification and homogenization in wood by steaming is common technique to improve wood attractiveness, yet for some species, the knowledge on such treatment is lacking. This study aimed to investigate the effects of steaming on colors creation and homogenization on sugi (Cryptomeria japonica D. Don) wood. Sugi wood samples were steamed applying broad range of steaming time (0-20 days) at 90 and 110°C steaming temperatures. The color change was monitored objectively using the CIE Lab color system. A wide range of colors was created by steaming between the initial color and light brown color depending on the steaming time and temperature. The initial color of earlywood and latewood within sapwood and heartwood covered a wide range of hues. The initial redness and yellowness values ranged from 4.3 to 17.3 and 21.4 to 31.6 units, respectively. Steaming produced excellent color homogenization and increased saturation. After 9 days of steaming at 110°C, redness values converged, falling between 11.6 and 12.7 units. The yellowness values increased and also converged. After 9 days of steaming at 110°C the yellowness values were between 31.6 and 33.5 units. The color saturation of the examined tissues increased considerably and was also showed homogenized. After 9 days of steaming at 110°C, the saturation values were between 34.1 and 35.6 units (the initial values were between 22.6 and 32.1). It was difficult to differentiate the sapwood and heartwood at the end of the steaming process at 110°C.