Frosting Paint

Frosting Paint

A white, salt-like substance on the paint surface. Frosting
can occur on any paint color, but it is less noticeable on
white paint or lighter tints. On masonry, it can be
mistaken for efflorescence (see Efflorescence and
Mottling).

Possible Causes Frosting Paint

Forms mostly in protected areas (such as under eaves and on porch ceilings) that do not
receive the cleansing action of rain, dew and other moisture.
Use of dark-colored paints that have been formulated with calcium carbonate extender.
Application of a dark-colored paint over a paint or primer containing calcium carbonate
extender.

Solution Frosting Paint

Frosting can be a stubborn problem. It often cannot be washed off readily. Moreover, the
condition can recur even as a bleed-through when a new top coat is applied. In extreme
cases, it can interfere with adhesion. The best remedy is to remove the frosting by
wirebrushing masonry or sanding wood surfaces; rinse, then apply an alkyd-based primer
before adding a coat of high quality exterior paint.