Bubbles caused from a loss of adhesion and lifting of the paint film from the underlying surface.
Heat blistering caused by painting in direct sunlight on a surface that is too warm.
Moisture blistering can be caused by the migration of water through an interior wall to the exterior, thus pushing the paint off of the surface.
Application of oil-based or alkyd paint over a damp or wet surface.
Exposure of latex paint film to dew, high humidity, moisture, or rain shortly after paint has dried, especially if there was inadequate surface preparation and/or poor ventilation in areas such as kitchens and bathrooms.
Moisture seeping into the home through the exterior walls.
Insufficient surface preparation, painting over a contaminant that the coating cannot adhere to.
If blisters go down to the substrate (e.g. the surface that is painted), the cause is likely to be moisture escaping from the surface. Remove all loose paint (by scraping or other method) and sand the surface to smooth out any rough edges. Determine and repair any cause of excess moisture before repainting. Repair old or damaged caulking or install new caulking as needed, install vents or exhaust fans or siding wedges to allow the moisture a path to escape instead of going through the paint.
If blisters go down to a previous coat, remove all loose paint (by scraping or by other methods), and sand the surface to smooth out any rough edges. Sand any glossy surface to a dull finish. Allow sufficient drying time after cleaning.