Effect of Heat Treatment on the Color Change of Blue-Stained Pinus densiflora Boards

열처리에 의한 청변균 변색 소나무 판재의 재색 변화

Red pine is a popular species for making a cutting board in Korea, but easily sap stained. Heat treatment could improve its quality by darkening and equalizing the color of sap stained wood. The color change of sap stained red pine boards was investigated by heat treatment at $190^{\circ}C$. It was observed that the color of heat treated boards got darker and it made the color of sap stain vanished. A colorimeter was used to measure color indexes. It was revealed that the values of the lightness ($L^*$) and the yellowness ($b^*$) decreased as heat treatment repeated while the values of the redness ($a^*$) increased. The average of the color difference (${\Delta}E^*$) between the control and 1st heat treated boards was 16.1, which could be expressed as 'Extremely different' while that between the 1st and 2nd heat treated boards was 8.3, which could be expressed as 'Considerably different'. The fact that heat treatment equalized the color of boards was confirmed by a statistical analysis.