This standard describes procedures for outdoor exposure testing of coatings on metal substrates, including new and rusting steels. Its purpose is to assess the performance of coatings in the natural environment. Test results may vary from location to location due to factors such as solar radiation, Humidity, temperature and contaminants. A single test does not accurately predict long-term degradation of materials. Years of sexual repeability exposure are required to obtain reliable data. The standard recommends testing under different climate conditions and comparison using control materials to assess weathering resistance of coatings.