Stains in the paint surface caused by virtually anything that would bleed, leak, or stick to the paint film.
Water: The source of the water must be found and repaired. Excessively damaged wood, plaster, or drywall may need to be replaced. Peeling paint must be removed if present. The stained area must be properly sealed with a primer designed to “hold out” water stains.
Tobacco smoke stains, fire smoke and soot, and grease and oil all should be cleaned as much as possible from the surface using ProClean Professional® PrepWash Cleaner or other appropriate cleaner. Stains must be sealed before topcoating.
Rust must be mechanically removed (with a brush or power tool) and the substrate (e.g., the surface to be painted) primed with a rust-inhibiting primer.
Tannins are extractives found in wood that can be leached out, generally with water, and discolor a coating. (See Tannin Staining for more).
Solvent-soluble stains (stains that may be removed with a solvent-based cleaning solution): oil, grease, tar, solvent-based markers, etc., and minor dried water stains.
Water-soluble stains (stains that may be removed with water-based cleaning solution): dried water stains, smoke stains and related odors, grease, ink, and pencil stains.