The ASTM C1501-2019 standard provides a laboratory accelerated aging test method for evaluating the colour fastness of sealants in building structures. The test simulates the effects of sunlight, moisture and heat on sealants and their pigments, but does not include local efflorescences such as atmospheric pollution or saline water exposure. The test uses Fluorescent Ultraviolet or Xenon-arc equipment, and the appropriate Light source needs to be selected according to the actual application. Test results may vary depending on the Light source, so the performance of sealants in different equipment cannot be directly compared. The standard specifies test conditions and evaluation techniques, and does not include ISO equivalence standards.