Loss of a coating's (e.g. primer, paint or stain) adhesion from plaster, which can occur in spots or larger areas.
Peeling from plaster could be a result of insufficient wet troweling of the white coat when the plaster was originally applied, causing chalking of the surface.
Very hard plaster may be slick, reducing the adhesion of any coating.
New plaster might have a high pH, requiring the application of a primer resistant to alkalinity.
Old plaster that has become powdery.
Poor surface preparation.
Bare plaster must be cured and hard. Textured, soft, porous, or powdery plaster should be treated with a solution of 1 pint household vinegar to 1 gallon of water. Repeat until the surface is hard; rinse with clear water and allow to dry. All new plaster should be primed after it has been cured a minimum of 30 days. If painting cannot wait 30 days, allow the surface to cure 7 days and prime with PrepRite® Masonry Primer.
If peeling has already occurred, remove as much of the coating as possible by sanding or scraping before repainting. Test the coating in a 6" to 12" radius around peeled areas to be sure the adhesion is adequate.
Cracks and holes in plaster should be repaired before repainting. Make sure the newly repaired plaster is similar in surface texture to the adjacent plaster so that the repaired area blends in with the original area.
Follow label and data page information for proper surface preparation and application.