Solutions For Blistering Cont.. And “Checking”: By Vancouver’s Best Painters

Solutions For Blistering..cont And Checking

If the blistering was caused by moisture, a number of solutions exist. Repair loose caulking and install vents or exhaust fans, if necessary. If the home has lap siding, siding vents can be installed under the siding in areas where blistering has occurred. This will allow moisture from the inside of the house to evaporate before penetrating the wood siding, preventing future blistering problems. Sand and scrape the peeling paint to bare wood; prime exposed areas and repaint. If large areas of the painted surface have blistered and need to be removed, high-pressure washing or the use of a heat gun will speed the removal process.

If the entire house is reprimed, but stands without the finish coat for an extended period of time, more blisters may develop. These should be scraped smooth and spot-primed before applying the finish coat. Blistering is the beginning stage of peeling. Blistering problems and solutions are discussed in more detail later in this module.

CHECKING

Checking (Figure 3) is shallow breaks in the coating film that do not penetrate to the substrate.  Slight checking indicates a relieving of the shrinkage stresses in a paint film. If the film does not check, it may crack due to greater tensile strength and the expansion and contraction of the coating film.  Characterized by a pattern of short, narrow breaks in the top layer of paint, checking usually develops as the paint begins to lose its elasticity. The underlying layers of numerous coats of paint become brittle and no longer expand and contract in response to changes in temperature and humidity. As the wood swells, stress breaks the bond between layers and checks form. Plywood is likely to check because of its construction.

Solution

Remove as much loose paint as possible with a scraper and wire brush and smooth the surface with sandpaper. Use exterior spackle to level material that cannot be removed. If many layers of coating are involved, you should probably remove all the paint to the bare wood to avoid unevenness and prevent rechecking. Prime all bare wood and let it dry; then apply the finish coat. Be careful not to apply it too thickly or when the temperature is too high.

Rick Anderson

www.vancouversbestpainters.com

www.vancouverindustrialpainting.com

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