Problem Solving Forum
June 21 - June 25, 2021
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?
Zenith Czora of Durotech Industries, Inc. on
June 24, 2021:
Depending on the severity of the damage, on or mor ...read more Depending on the severity of the damage, on or more methods can be used to prepare the surface for a new coating: scraping the damaged or blistered paint film to bare surface, then sanding the surface to the desired surface profile/smoothness and dedusting and wiped clean with clean rags. Ensure that there is no trapped moisture with in the wall. The trapped moisture can lead to growth of molds, mildews and bacteria and reoccurrence of blistering on new paint that will lead to delamination. Check the moisture level of the concrete. Walls have to be dry enough before new coating to be applied. Drying the wall can be done using an air mover blowing warm, dry air along the wall surface. If one side of the wall is exposed to the water/moisture elements and the other side is heated or airconditioned, a breathable water repellent based on silane, siloxane, or silicone technology decorative surface coating is more suitable. This type of coating lets water vapour move in and out the wall and prevent most wind-driven rain.