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.
SOLUTION:
If blisters do not go all the way down to the substrate: We remove blisters by scraping,
and sanding, and repaint with a quality acrylic latex interior paint. If blisters
go down to the substrate: We remove the source of moisture, if possible. Repair loose
caulking; consider installing vents or exhaust fans. Remove blisters as above, remembering
to prime before applying the top coat.