Bubbling Paint | Calgary Paint Repair
Bubbling paint can happen for a few main reasons. Below is a discussion of the causes and the solutions.
Bubbling from moisture issues:
The most common reason for painting bubbling is moisture issues. Often, paint will bubble on exterior wood if there is a moisture issue on the opposite side of the wall. For example, a bathroom with poor ventilation could cause issues for the siding.
When moisture is trapped in the substrate, it evaporates through the coating and pushes the film out.
If a moisture issue exists, it is best to solve that issue before trying to fix the bubbling paint.
Afterwards, scrape back all of the bubbling paint and sand thoroughly with a medium grit. Applying an oil-based primer is a good idea for sealing the area.
Bubbling from chemical reactions:
Moisture issues can be ruled out by using a moisture meter to check if the surface is dry enough to properly accept paint.
Sometimes, on old siding that has been painted many times over its life, bubbling can occur upon a fresh coat. This is because there is problem with adhesion of the older layers of paint. Incompatible paint products work against each other. Modern latex products want to breathe, while older, oil-based products work to seal everything out. The result is a “shearing” force that will cause bubbling, all the way down to the wood.
Trying a variety of slow drying, shellac or oil-based primers can often help. Sometimes, however, the only way to fix the problem is to remove all of the old layers of paint, or simply replace the siding.
Bubbles from improper preparation:
Improper preparation includes poor scraping, sanding and not waiting for the correct conditions to apply primer and paint. Again, moisture is usually the biggest culprit.