Evaluation of three surfacing methods on paper birch wood in relation to water- and solvent-borne coating performance

Helical planing, face milling, and sanding were used to surface paper birch wood prior to application of coatings. The surface roughness and wetting properties of the wood were evaluated as well as the pull-off strength of water- and solvent-borne coatings, before and after aging. The specimens surfaced with helical planing produced surfaces with the highest surface roughness, the best wetting properties, no subsurface damage, and good pull-off strength before aging. Those surfaced with face milling generated surfaces with intermediate surface roughness, lowest wetting properties, slight surface and subsurface damage, and good pull-off strength before aging. The sanded samples produced the lowest surface roughness, intermediate wetting properties, the highest surface and subsurface damage, and good pull-off strength before aging. After aging, all samples coated with the same varnish exhibited the same pull-off strength regardless of the surfacing treatment. However, loss in pull-off strength after aging was lower for helical planing than for the others. This suggests that helical planing could produce more suitable surfaces for indoor furniture applications. Finally, the water-borne coating created stronger bonds with the substrate than the solvent-borne coating.