The Optical Appearance of Wood Related to Nanoscale Surface Roughness

Abstract

The color and appearance of timber is influenced by a variety of physical and chemical effects. Especially the chemical composition and the surface structure play a major role. In particular, the influence of chromophore extractives and the effect of thermal degradation processes on the color of wood are widely discussed in the literature. The present study deals with the influence of the surface nanostructure on the visual appearance of wood. This new perspective should generally demonstrate various influences on the appearance of natural inhomogeneous surfaces. Therefore, two methods were used to change the nanoroughness of lignocellulose materials. With different oil coatings and UV-irradiation, the surface structures of the samples were changed, and the measured roughness using atomic force microscopy was then correlated with the collected brightness differences. The results show that a clear correlation exists between the nanoroughness altered by oil coatings or UV irradiation and the brightness of the wood surface. Due to various other influences, such as chemical changes and light refractions of the treated wood structure which also influence the color of wood, no quantification can be given at this point.