Changes in the surface properties of wood due to sanding

Spruce and beech wood specimens were sanded with four different grain sizes. Surface morphological and chemical changes were determined by roughness measurement, surface free energy determination according to acidbase theory and Xray photoelectron spectroscopy. An analysis model was proposed to describe chemical changes due to sanding and the data were analysed according to it. It could be shown that spruce and beech behave similarly over a wide range and that chemical changes are nonlinear functions of grain size and thus surface roughness. A maximum of surface free energy and a maximum of carbon C1s subpeak ratio (ratio of carbon bonded to a single noncarbonyl oxygen to carbon bonded only to hydrogen or other carbon atoms) was found for middle grain size.