Describes two methods of exposure. In method A, the material is exposed under glass to natural light. In method B, the material is exposed to direct artificial light. The test sample and the agreed reference pigment are each dispersed in the same agreed binder. The dispersions are applied to a substrate and dried; they are then exposed to natural daylight with protection from rain (method A) or to artificial light (method B) under specified conditions. The resistance to light is assessed by comparing the change in colour of the test sample to that of the agreed reference pigment. Cancels and replaces the first edition ISO 787/15-1973.