Bleach deteriorates upon standing and loses its potency. Some paints are more vulnerable than others to attack by mildew fungi. Zinc oxide, a common paint pigment in top coats, inhibits the growth of mildew. Titanium dioxide, another common paint pigment, has very little inhibiting effect on mildew. Considering oil-base paints, mildew progresses more readily on exterior flat house paint than on exterior enamel.
Paints containing linseed oil are very susceptible to mildew.
Of the available water-base paints, acrylic latex is the most mildew resistant. Mildewcides are poisons for mildew fungi. The paint label should indicate if a mildewcide is present in the paint. If it is not present, it can sometimes be added by the local paint dealer. Paint containing mildewcides, when properly applied to a clean surface, should prevent mildew problems for some time.