Determination of the effects of ultrasound supported varnish-component mixture on layer quality

Wood material is a sustainably sourced precious material that has been used in many areas for centuries. However, wood material is not very resistant to outdoor conditions. Increasing the useful life of wood material plays an important role in the efficient use of resources. One of the most important processes in prolonging the useful life of this valuable material is the surface treatment, while the surface treatments not only add aesthetic value to the material, but also provide protection against biotic and abiotic factors because it cuts the moisture exchange. Varnishes, which are commonly used in surface treatments, may be short-lived due to the mixing method. Cavitation gaps that occur during the mixing of varnish-component components adversely affect the adhesion of the varnish to the wood material, the formation of capillary cracks, the inability to obtain a homogeneous surface, the surface gloss and many other quality properties. The aim of this study is to eliminate the cavitation gaps that occur during the mixing of the varnish by ultrasonic mixing method and to increase the quality of the varnish layer. For this purpose, polyurethane, acrylic and polyester varnish systems were applied on three different wood types, namely Scots pine (Pinus sylvestris L.), Eastern beech (Fagus orientalis Lipsky) and Mahogany (Khaya ivorensis), with Mechanical and Ultrasonic mixing methods. In the mechanical mixing method, 3, 5 and 7 minutes were applied, while in the ultrasonic mixing method, 80 Watt, 120 Watt and 160 Watt wave intensities were applied during mixing in addition to these times. The obtained test samples were subjected to gloss, surface hardness, surface scratch resistance, surface adhesion resistance and surface roughness tests and the performances of the mixing method were investigated. As a result; According to the scratch resistance findings, it was observed that the ultrasonic mixing method had a negative effect among the three varnish types, and a decrease in the scratch resistance of the varnish occurred in parallel with the increase in the ultrasonic wave intensity. When the surface hardness findings were examined, it was observed that the surface hardness resistance of the polyester varnish type was higher than the other varnish types, but when the mixing methods were compared, it was also observed that the mechanical mixing method gave better results than the ultrasonic mixing method. When the surface resistance findings are examined, the polyurethane varnish type showed better results than other varnish types, while the polyurethane varnish type gave good results in the mechanical mixing method, the increase in the wave intensity in the ultrasonic mixing method affected the varnish adhesion resistance inversely. It has been observed that ultrasonic mixing method has positive effects on varnish adhesion resistance in acrylic and polyester varnish types. According to the surface roughness test results, the test samples of the polyurethane varnish type applied with the mechanical mixing method showed the best result (least rough). The increase in the wave intensity in the ultrasonic mixing method did not show good results in inverse proportion. It was observed that tree species had no effect on the surface roughness and that the three tree species used in the examples gave similar results. According to the surface gloss test results, the polyurethane varnish type has the best surface gloss values. When the tree species used in the experiment were examined, the scotch pine test specimens gave better surface gloss results than the other tree species. It has been observed that the ultrasonic mixing method gives better results than the mechanical mixing method at 80 and 120 watt wave intensities.