*** MILDEW
Mildew looks like conventional grime, but is actually a living fungus which eats proteins and nutrients contained in paints and substrates. If you are not sure whether your problem is dirt or mildew, place a spot of bleach on the affected area. Only mildew will react by whitening Some of of Paint contains agents which inhibit the growth of mildew on the surface; however, if mildew is present prior to painting, growth may still occur.
Solution: since moisture is essential to the growth of mildew, you must take preventive action against moisture to avoid recurrence. To clean mildew from surface, use a solution of 1 quart household bleach in 3 quarts of water making sure skin and eyes are protected. Rinse with clean water and allow to dry thoroughly. Scuff sand glossy surfaces. Sand down badly weathered areas and spot prime.
Tags: Painting Information