Weathering testing of coatings: Recent developments in international standardization

 
A current trend in standardization is more realistic simulation of natural weathering conditions. This resulted in the development of a weathering test method for transportation coatings in humid climate zones (ASTM D7869) and in more realistic spray cycles for plastics in ISO/TC 61/SC 6. Focus is also given on better control of the test parameters. This includes: ? redefinition of daylight filters for xenon-arc instruments in ISO 16474-2 and ASTM G155 ? recalculation of the reference sun in CIE 241 ? a recommended chamber air temperature setting in G155, and ? measurement of the amount of water spray in ISO 23741. Better control and understanding of the parameters in accelerated testing, does not only help to improve correlation to natural weathering, but also to increase reproducibility. Test methods which provide additional acceleration over natural weathering compared to existing methods also gain increasing interest. New standards provide guidance on these accelerated methods and how they can be implemented. An overview will be provided on recent developments in ISO and ASTM standardization and how these developments influence weathering testing in the coatings industry.