The ASTM D4610-98 (2021) standard guidelines are designed to identify the growth of microorganisms (such as fungi or algae) on paints and coatings and their removal methods. The growth of microorganisms can lead to film discoloration or performance degradation, and this guide provides techniques for identifying and removing these contaminants. In particular, for post-coated surfaces, the guidelines recommend thorough cleaning steps to avoid the effects of residues on new coatings. While the guidelines apply to re-coated surfaces, special attention should be paid to warnings about bleach use in case it negatively affects the film.