Mildew

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

Possible Cause :

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

Solution :

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