GB/T 37356-2019 "Paints and varnishes — Lighting conditions and methods for visual assessment of coatings" is applicable to the visual assessment of surface defects, aged areas, etc., of coatings, and specifies corresponding lighting conditions and operational methods. For routine assessments, diffuse natural daylight (illuminance not less than 2000 lx) may be used. For arbitration assessments, artificial daylight lamps with a color temperature of 6500 K and a color rendering index of 90–100 (illuminance not less than 750 lx) must be employed. During observation, the test panel may be tilted to identify defects at the junction of light and shadow. The standard clarifies the arrangement of light sources, observation distance, and environmental requirements, providing a unified standard for the visual assessment of coatings.