GB/T 6739-2022 "Paints and varnishes - Determination of film hardness by pencil test" replaces GB/T 6739-2006 and is a modified adoption of ISO 15184:2020. It is applicable to the determination of the hardness of the top film of single-layer and multi-layer coatings for paints, varnishes, and related products. The standard specifies that the test is performed by scratching the film at a 45° angle with a pencil under a load of 7.35±0.15N, and the result is expressed as the hardness of the hardest pencil that does not cause defects. It stipulates that test panels should be conditioned at 23±2°C and 50±5% relative humidity for at least 16 hours. The test is conducted in duplicate, and if the results are inconsistent, they are determined according to specified rules.