This part of the EN 13523 series specifies the basic principles and procedure for determining the resistance of an organic coating on a metallic substrate (coil coating) to a combination of fluorescent UV radiation, and water condensation and temperature under controlled conditions. Due to varied conditions which occur during natural weathering and the extreme nature of accelerated testing, correlation between the two cannot be expected. Not all organic coatings will perform on an equal basis but a degree of correlation between the same generic type might be observed.