A reliable artificial weathering test for wood coatings: Fid-Bau Portal

A reliable artificial weathering test for wood coatings

Podgorski, L. / Arnold, M. / Hora, G.

The principal aim of this European research project was to develop an artificial weathering method to assess the durability of exterior wood coatings in a short time period. The objective was to base the method on the modern and relatively low-cost fluorescent lamp apparatus originally developed for coated steel and plastics substrates, adapting equipment and operating cycles to meet the needs of wood substrates. Several cycles were defined from the experience of the 14 partners involved in this project. They included different types of UV radiations, condensation, spray, high and low temperature, freezing, soaking. These cycles were tested on 6 coatings systems. From the results obtained with these cycles it has been possible to define an optimised cycle. This cycle is made of 24h of condensation followed by a sub-cycle of 2.5hours of UVA-340nm and 0.5 hours of water spray. The reproducibility of this cycle has been studied: 8 partners tested this cycle with the same six coatings using a detailed test procedure. The reproducibility was correct even if some sources of variation have been identified. Then this optimised cycle has been tested on several coatings. The purpose of this task was to investigate if further variations in systems and products used on exterior wood compared to the first 6 systems used in the main experiments would follow the performance known when the optimised cycle is used. The performance for the alkyd systems followed the general trend which was observed at outdoor exposures on pine panels but also the experience obtained from exposures at joineries, facades etc. For the acrylic systems the performance compared to outdoor exposures is very depending on the pigmentation.