As powerful as PX10 is, its only drawback is that it is not designed to be a stain remover. PX10 will remove light stains on drywall and wood but will not completely remove darker, deeper stains. We are working on a simple solution to this, but for the moment simply use PX10 to eliminate the mold and then apply any other stain remover. After all, once you use PX10 it’s now only a stain!