This International Standard is one of a series of standards dealing with the sampling and testing of paints, varnishes and related products. It specifies a test method for assessing either the resistance of paint coatings to artificial weathering or the resistance to light by exposure to artificial radiation. The standard describes the most important parameters and specifies the conditions to be used in the exposure apparatus. Provided the test conditions specified are strictly respected, reproducibility is improved and an improved correlation is obtained between natural-weathering and artificial-weathering tests.