Blistering is usually caused by the evaporation of trapped moisture or solvent. If surfaces are painted shortly after washing down, even if time is allowed for surface drying, blistering may occur as a result of moisture absorbed into the old paint. Painting in the direct heat of the sun may result in rapid “Skin Drying” causing solvent to be trapped in the film. Recoating before the previous coat is hard may cause blistering for the same reason.
Possible Causes:
- Applying oil-based or alkyd paint over a damp or wet surface.
- Moisture seeping into the home through the exterior walls (less likely with acrylic paint).
- Exposure of acrylic paint film to high humidity or moisture shortly after paint has dried, especially if there was inadequate surface preparation.
Solution:
- Open all the blisters and leave the entire surface to dry.
- Sand the surface to obtain a smooth surface
- Spot prime with Rainbow Fresh Plaster Primer over the affected areas.
- Apply the selected topcoat. – (Rainbow Exterior Paint, Long Life Acrylic or Weather Shield Paint