Bubbles resulting from localized loss of adhesion, and lifting of the paint film from the underlying surface.

• Applying oil-based or alkyd paint over a damp or wet surface.

• Moisture seeping into the home through the exterior walls (less likely with latex paint).

• Exposure of latex paint film to high humidity or moisture shortly after paint has dried, especially if there was inadequate surface preparation.

• Application of emulsion pints on a wall that has previously been painted with a clay based paint

If blisters do not go all the way down to the substrate: Remove blisters by scraping, and sanding, and repaint with a quality interior paint. If blisters go down to the substrate: Remove the source of moisture.