Surface Roughness Evaluation Methods for Wood Products: a Review

Purpose of Review Although surface roughness can have a huge impact on finishing costs and the perceived quality of wood products, there is a lack of consensus on how to measure and evaluate wood surface roughness. One reason for this is that the presence of anatomical features can bias the measuring and evaluation of surface data. Consequently, the methods and recommendations given in general standards on measuring surface roughness do not apply well to wood surfaces. This review offers some recommendations on how to best measure and evaluate surface roughness. Recent Findings This review covers the measurement (instruments, methods, profile measurements versus area measurements, measuring length and resolution) and evaluation (form error removal, filtering, the selection of the cut-off length, removal of wood anatomy from the measured data, calculation of roughness parameters) of surface roughness of wood products. Summary A set of best practices in order to overcome the biasing effect of wood anatomy is presented in this paper. Specific recommendations are given regarding the selection of the measuring instrument (stylus), the length of evaluation (at least 40 mm), the measuring resolution (5 mu m), removal of form error (with or without prior removal of wood pores), the use of the Robust Gaussian Regression Filter, appropriate cut-off length (2.5 mm), the best roughness parameter for describing the processing roughness (Rk) as well as a method to separate the processing roughness from anatomical roughness by using an Abbot-curve. These findings, if automated in dedicated software can serve for optimisation of processing parameters in industry applications.