GB/T 5211.9-2025 "General Test Methods for Pigments and Extensions, Part 9: Comparison of Light Resistance of the Same Type of Chromadizing Pigments" specifies the comparative test method for the light resistance of the same type of chromadizing pigments. The standard specifies the test principle, equipment, Sample Handling, operation procedures and result evaluation, etc., which is suitable for the comparative detection of the light resistance performance of similar chromadizing pigments. It provides a unified specification for evaluating the Stability of pigments under light, and helps the quality control and application selection of related products.