Question：Interior Painting Problems: Blistering?
Painting a damp, dirty, or hot surface.
Applying oil-based or alkyd paint over latex paint.
Improper surface preparation.
Exposing latex paint to moisture shortly after paint has dried.
Make sure the surface is clean and dry.
Apply primer-sealer over any stains and let it dry completely.
Prime new joint compound with flat latex paint or latex primer.
Avoid painting in hot or humid conditions.
Let paint dry completely before exposing the surface to moisture.
Consider installing vents or exhaust fans in humid areas.
If the blisters do not go all the way down to the substrate, remove them by scraping and sanding. Once the problem area has a smooth finish, coat with primer before applying a quality acrylic latex interior paint.
If the blisters go down to the substrate, you will need to remove the source of moisture, if possible.
Repair loose caulking and consider installing vents or exhaust fans to lower the humidity in the house.