This standard is used to evaluate the hiding power changes of architectural coatings during drying, especially white and light-colored coatings. The hiding power of coatings during drying can change significantly due to factors such as porosity and film integrity, which can affect the actual effect of coatings. The test method measures the hiding power changes by visual evaluation of wet-film and dry-film, assisting paints specification development and quality control. SI units are standard units, and the values in parentheses are for reference only. It is up to the user to determine the applicable safety measures.