November 25 - December 6, 2013
During a week of heavy rain, we painted the interior of a heated concrete building. The paint blistered badly a week later on the walls with an outside exposure. What’s the best way to remove the coating, prepare the surface, and recoat to prevent future blistering?
Car F. of Municipal City on
December 3, 2013:
Before doing anything on the INSIDE, I would investigate what’s on the outside walls and what kind of waterproofing was applied [if any] to the exterior walls. You seem to indicate that the walls NOT facing the outside were fine, so this may point to a problem related to the exterior walls and not necessarily to the actual coating. Concrete is not impervious, and water and moisture will migrate, sometimes a great distance.
juan hurtado of International Paint on
November 27, 2013:
You can also remove the coating by blasting with with crushed walnut shells, which is a lot faster than soda blasting.And I would also recommend checking the concrete for moisture.
Michael Quaranta of OPERATIONS 40 on
November 25, 2013:
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Well, for the first element of searching for a response, what kind of coating was used? Probably the heated concrete building was very high in interior humidity, and if you used the standard epoxy, it was doomed for failure. Without knowing what coating was used, it becomes a guess about the best the removal process. Soda blast would be slow but perhaps the best. Next, use a water-based epoxy, and either spray of roll that coating (colors available) on the concrete wall. The pot life is more than 2 hours and the cure is razor-proof after 24 hours.
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