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Blistering Paint

Blistering paint is identified by small- to medium-sized bubbles or blisters under the paint film. It is most commonly seen on wood siding and trim.

Possible Causes

o Paint was applied in direct sunlight on a hot surface, which trapped solvent vapor as the paint dried too quickly.
o The Paint was applied when the wood was damp, causing trapped moisture to expand the paint film.
o Dew, rain or very high humidity penetrated after latex paint dried—a common problem if the latex paint was of lower quality or if the substrate surface preparation was inadequate.
o House moisture escaped through the walls due to improper house ventilation.

Repair and Prevention

o Scrape away blistered paint, and sand to bare wood. Let wood completely dry before painting.
o Make sure to sand, prime, and paint in non-direct sunlight and in non-humid conditions.
o Use high-quality latex paint.
o If due to lack of home ventilation, corrective repairs must be made to properly ventilate the home's walls, roof, and eaves, bathrooms, etc.
o Check and repair any loose or missing caulking around windows and doors.
o Consider providing siding ventilation.

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