Analysis of the impact of blue stain on the color, glossiness, and whiteness properties of scots pine lumber

Blue stain causes bluish to purplish discoloration in Scots pine wood, reducing its aesthetic value. It is generally caused by saprophytic fungi that colonize the wood surface; while it does not affect structural strength, it leads to a loss in commercial value. Moreover, this condition can impact export quality and limit the potential applications of the wood. Blue stain negatively affects the production process by complicating the drying phase, while its visual defects reduce customer perception, and the chemical treatments required to prevent or remove the staining increase production costs. This study investigates the changes in color parameters, glossiness values, and whiteness index of Scots pine (Pinus sylvestris L.) wood with blue rot compared to normal yellow pine wood. The study compares color parameters such as lightness (L*), red (a*), yellow (b*), chroma (C*), and hue angle (ho), as well as glossiness measurements at 20°, 60°, and 85° angles, and whiteness index (WI*) values. Significant changes in color parameters were observed in the wood with blue rot. The L* value decreased by 11.43%, the a* value decreased by 79.95%, and the b* value decreased by 28.86%. The C* value decreased by 32.75%, while the ho increased by 17.74%. These results indicate that the wood with blue rot has a darker, greener, and more matte appearance. In the glossiness tests, the glossiness value of the wood with blue rot showed a slight decrease at the 20° angle compared to the normal test sample.