The BS EN ISO 28199-3:2021 paints and varnishes - Evaluation of coating system performance in relation to the application process, Part 3: Visual assessment of pinholing and hiding power, bubble formation, sink sinking - details the test method for visually assessing the critical performance of a coating system. This section focuses on the observation of pinholing and hiding power, the degree of bubble formation, and possible sink sinking on the coating surface, providing a standardized evaluation procedure and basis for determination. Applied to paints and varnishes application research, quality control and product development, the standard helps users evaluate the performance of coatings under specific conditions and improve process parameters to ensure product mass and final performance.