Determination of the resistance of water based layers on some heat treated (Thermowood) wood species against accelerated uv aging

The objective of this study, to investigate accelerated UV resistance of water-based varnish layers applied on heat treatment wood (ThermoWood) surfaces. In this study, wood specimens prepared from scotch pine, oak and beech wood species were heat treated according to ThermoWood method at 190oC for 2 hours and 212oC 1 to 2 hours. Following the heat treatment one and two component water-based varnishes were applied in similar layer thicknesses according to manufacturer recommendations. The finished specimens were exposed to UV-A 340 nm flouresent lamp in a QUV accelerated weathering tester for 144, 288 and 432 hours. At the end of each exposure period color (ΔE, ΔL*, Δa* and Δb*) (ASTM-D 2244-3), brightness (ISO 2813), surface roughness (Ra, Rz and Rmax) (ISO 4287), surface adhesion resistance (ASTM D 4541), hardness (ANS/ISO 1522) and scratch resistance (EN 15186) values were determinated. According to the results, while the brightness, surface adhesion and surface roughness values of water – based single double component varnish layers on heat – treated wood decrease, color, hardness and scratch resistance values increased.