Determination of the resistance of the layers of teak oil, synthetical varnish and water based layers that are applied on certain heat-treated wood species against accelerated UV ageing effect

The objective of this study were determined some physical, mechanical and technological properties of some foreign heat-treated woods such as American Ash (Fraxinus Americana), European Alder (Alnus incana) and also those of some national heat-treated woods such as white poplar (Populus alba) and white willow (Salix alba) the four above mentioned wood types will be heat - treated at two different temperatures of 190 0C and 212 0C and for two different durations of 1.5 and 2 hours. By making use of the heat-treated test samples, of the physical properties; air-dry density, oven dry density, of the mechanical properties; compression strength parallel to grain, bending strength, and dynamical bending (shock) strength, and of the technological properties the hardness value (janka) were determined. Then, for each group on the material surfaces, synthetic varnish, one component water-based varnishes and teak oil were applied in industrial applications. The acquired materials after these processes were exposed to UV light for 144, 288 and 432 hours in a QUV accelerated weathering tester device with UV-A 340 nm fluorescent lamps and at the end of age hardening periods, color (∆E*, L*, a* and b*), glossiness, wettability and surface adhesion strength were determined in the varnish layers. As a result; in heat-treated test samples, decrease in bending strength and dynamical bending (shock) strength values were determined by increasing the heat treatment temperature and it was determined that there was an increase in the strength values of the hardness (janka) and the compression strength parallel to grain. In the test samples with different varnish types, the heat treatment temperature increased at the heat treatment factor level, the a* values, the b* values, the lightness (L*), the total color change (ΔE *), parallel (//) glossiness to grain, perpendicular (⊥) glossiness to grain, surface adhesion strength and wettability test contact angle values were found to be decreased. At the weathering period level, a decrease in the a* values, the b* values, the parallel (//) glossiness to grain values, perpendicular (⊥) glossiness to grain and surface adhesion strength values were determined as an increase in the lightness (L*), the total color change (ΔE*) and wettability test contact angle values as a result of the elapse of the weathering time.