Comparison of wood coating durability in natural weathering and artificial weathering using fluorescent UV-lamps and water

Panels of pine sapwood coated with 30 different coating systems were exposed to natural weathering in Vienna as well as artificial weathering using fluorescent UV-lamps and water. The aim was to compare coating durability in natural and artificial weathering in terms of the exposure time until the panels reached a defined limit state where the coatings required maintenance. For both weathering methods the durability of the coating systems was influenced by film thickness and for the semi-transparent systems also by pigmentation. Three opaque coating systems lasted over 10,000 h of artificial weathering. Comparison of the natural and artificial weathering regarding durability of the coating systems (time to limit state) with the present results (after 30 months natural weathering) revealed a non-linear correlation. The collected data can provide a basis for rough service life estimation of exterior wood coatings based on standardised weathering methods.