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Solving Mildew Problems2021-05-17T09:15:07-04:00




Black, gray or brown spots or areas on the surface of paint or caulk.


  • Forms most often on areas that tend to be damp, or receive little or no direct sunlight (e.g., bathrooms, kitchens and laundry rooms).
  • Use of an alkyd or oil-based paint, or lower quality latex paint.
  • Failure to prime bare wood surface before applying the paint.
  • Painting over a substrate or coating on which mildew has not been removed.


  • Test for mildew by applying a few drops of household bleach to the area; if it is bleached away, the discolorant is probably mildew.
  • Remove all mildew from the surface by scrubbing with a diluted household bleach solution (one part bleach, three parts water), while wearing rubber gloves and eye protection.
  • Rinse thoroughly.
  • To protect against mildew, use a top quality latex paint, and clean when necessary with bleach/detergent solution.
  • Consider installing an exhaust fan in high moisture areas.

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: Images & information provided by The Rohm & Hass Paint Quality Institute.