Zinsser Mold Killing Primer is a water-based fungicidal protective coating that can be used to paint over existing mold, mildew, moss, fungi, odor causing bacteria and any other fungal organisms. The mold killing primer contains an epa registered antimicrobial to prevent the growth of mold, mildew and other fungal organisms on the paint film. Use indoors or out on a variety surfaces including under wall Coverings. Mold killing primer also aides in covering residual microbiological and fungal stains.