The Surface Roughness of Wood After Hard Wax Oil Treatment

The article presents a study on the surface roughness change of spruce (Picea abies Karst.), aspen (Popolus tremula L.), beech (Fagus sylvatica L.), ash (Fraxinus excelsior L.), and European oak (Quercus robur L.) after treatment with commercial hard wax oil. For the spruce specimens, measurements were also made after a water permeability test, according to CSN EN 927–5:2007, as well as after 72 hours of drying. Before coating application, the surfaces were sanded with P120-grain sandpaper. The second layer of coating was applied without intermediate sanding. A contact surface roughness tester model SJ-210 and a standard Gaussian filter were used for roughness evaluation. It was found that after the application and solidification of hard wax oil, the treated surfaces were less rough but with increased heterogeneity. The substrate properties (structure, density, and hardness) had a major impact on the investigated parameter values and changes. The beech wood roughness changed to the greatest extent. The most significant change was observed in the parameter RSm (119 - 35%). The coating was also found to impart form stability to the treated surfaces without being watertight. No grain raising was found.