Scratch resistance of cellulosic, synthetic, polyurethane, waterborne, and acid-hardening varnishes used on woods

This study was conducted to determine the scratch resistance of cellulosic (C), synthetic (Sn), polyurethane (Pu), waterborne (Wb), and acid-hardening (Ah) varnishes used on wood materials. Test samples were prepared from Scotch pine, oriental beech, European oak, black poplar, basswood, and black walnut woods that met ASTM D 358 requirements and were coated according to ASTM D 3023 standards with C, Sn, Pu, Wb, and Ah varnishes. The scratch resistance of the samples after the varnishing process was determined based on TS 4757. The greatest scratch resistance was obtained for walnut based on the wood species, whereas the least scratch resistance was obtained for poplar. As for varnish type, the greatest scratch resistance was obtained for synthetic varnish, whereas cellulosoic varnish had the least scratch resistance. In addition, the greatest scratch resistance was obtained for three layers based on the layer thickness, whereas the least scratch resistance was calculated for one layer. Based on the wood species, varnish type, and layer type, the greatest scratch resistance was found for oak + Pu + three layers, and the least scratch resistance was calculated for basswood + Wb + one layer. Furthermore, differences were observed according to varnish type and layer thickness; varnish types were efficient for scratch resistance to the first degree and layer thickness to the second degree. The results showed that a varnish application with three layers of polyurethane provides a durability advantage.