A white, salt-like substance on the paint surface. On masonry, it can be mistaken for efflorescence.
Frosting forms in areas that are protected from the cleansing action of rainfall. The crystals form when the paint is exposed to excessive moisture (dew, condensation, rain, etc.) or cool temperatures during the application and drying process. Frosting can occur on virtually any surface or substrate.
If frosting occurs, wash the crystal formations with warm water. Water-soluble crystals will disappear. Follow-up water flushing may be required at later dates, and eventually crystal formation will cease. If crystals are not water-soluble, then other actions are required. Allow surface to dry thoroughly. Using soft-bristle scrub brush, carefully scrub crystals away until original color of paint film reappears. Depending on the severity, this may be sufficient to remedy the problem.
If frosting residue remains, apply a coat of A-100® Exterior Oil Wood Primer. This oil undercoater will act as a barrier coat preventing the frosting from bleeding through. Apply another coat of the original finish.
Apply paint to all surfaces during weather conditions that allow proper curing of the paint film.
Note: Frosting may dissipate over time (several weeks or months) with no action taken.