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Why is my Paint Blistering? Get to the Root Cause.

By Mike Manetta, Target Account Executive

You’ve done everything you know how to prevent paint blistering. You primed, tested and timed everything just right — or so you thought. But every once in a while, you get bubbles and blisters. One of the most common questions we hear at Accessa is, “Why is my paint blistering?”

The first step to fixing blistering paint is isolating the root cause. If you try to fix the blistering without understanding why it happened in the first place, it will likely occur again.  Here are five of the most common causes of blistering paint and ways to help you determine if one of them is the reason your paint is blistering:

1. Incompatibility with the paint itself. Your paint could have either been mixed incorrectly or, if using a catalyzed product, the paint may not have catalyzed correctly. To determine if either of these are the case, check the manufacturer’s recommended mix ratio and test this ratio on a sample that is clean. If the sample does not blister, it could be that the paint you used was mixed incorrectly. If the sample does blister, it most likely means the paint did not catalyze correctly. In the future, check the mix ratio prior to using the paint and test it on a clean surface.

2.  Incompatible with primer. While it is always best to use a primer and top coat from the same manufacturer, blistering can occur when the primer and top coat are incompatible. To determine if this is the cause, contact the manufacturer and provide the MSDS (Material Safety Data Sheet) of the top coat and primer. Based on this information, the manufacturer will be able to tell you if incompatibility is the issue.

3.  Primer was not fully cured. Blistering can occur when the primer isn’t fully cured and the top coat was applied too quickly. Most paints dry by water and/or solvent evaporation. If the top coat is applied before the primer has had time to properly cure, evaporating water and/or solvents can get trapped in the top coat and cause blistering.

4. Surface contaminants. The most common cause of blistering is surface contaminants such as dirt, grease or oil. If you have tried the sample test explained above and the paint does not blister, take a closer look at what you are using to clean and how you are using it. Your cleaning method could be accidentally leaving contaminants that cause blistering.

5. Excessive heat. Some paints require certain temperatures to cure. If a paint is exposed to too much heat or exposed to too much heat too quickly, blistering can occur. Before applying a paint you are unfamiliar with, check the manufacturer’s specifications for any particular temperature cautions.

Once you have determined the root cause of blistering paint and have corrected the issue, you are ready to sand the area and reapply the paint. When you know why bubbles and blisters emerge from a seemingly clean coat of paint, you can prevent them, allowing you to avoid rework costs, stay on schedule and work more efficiently.

Contact me at 317-879-2055 to learn more about how Accessa can help you stay blister free. 

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