Influence of tannin containing coatings on weathering resistance of wood: Combination with zinc and cerium oxide nanoparticles

In this study, influence of tannin containing coating combined with zinc and cerium oxide nanoparticles on color, gloss, surface roughness and macroscopic changes of Scots pine wood after artificial weathering was studied. For this purpose, 3 different tannin types, valex, mimosa and pine with various concentrations, 2 metal oxides, nano zinc and cerium oxide, and a water based transparent coating were used. Commercially available nano wood coating was used as a reference chemical. Results showed that wood surfaces got dark color, lost the initial gloss and become rougher after weathering of 1512h. Samples coated with tannin and nano metal oxide containing coatings exhibited better protection against degradation factors than reference and controls. Among the treatments, low concentration levels of tannins and cerium oxide were found to be more efficient on protection of wood surfaces in comparison to high concentration levels and zinc oxide. General condition of samples seemed to be better for mimosa and pine tannins for ZnO combinations, and valex and pine tannins for CeO2 combinations after the weathering test. Results of such a combination system clearly showed amount of expensive inorganic nanoparticles could be reduced with the addition of natural antioxidants into transparent coatings.