Blistering is a loss of adhesion to the surface where the paint appears to be bubbled or blistered.
Blistering manifests itself as a raised area of paint that has separated from the surface. The key factor in blistering is moisture. When moisture in vapor form, liquid form, or solid form (ice) builds up on a surface, the paint coating blocks it from leaving the surface, so the water vapor, liquid water, or ice becomes trapped under the paint coating. The moisture can then drive the paint coating away from the surface, giving the paint coating a blistered appearance.
Cause 1:
Moist surface
If paint is applied to a moist surface, such as a surface that's covered with dew, the moisture can become trapped under the paint coating. When the moisture tries to evaporate away from the surface, it can push the coating outward, causing it to blister.
Cause 2:
Moisture movement
If moisture moves from the home's interior to the outdoors through the exterior walls, water droplets can form under the paint coating, pushing it outward and causing it to blister.
Cause 3:
Frozen surface
If paint is applied to a frozen surface, ice on the surface can drive the paint coating outward, causing it to blister.
Cause 4:
Cracks and unsealed edges
If moisture from dew, rain, snowmelt, and other sources moves behind cracks and unsealed edges in the home's exterior, it can become trapped behind the paint coating, fill the affected area with water, and blister the paint surface.
