![]() ![]() Defoaming additives are regularly added to latex paint to facilitate this air release process. ![]() When the air is forced up under a wet paint film the bubbles break and the paint flows back together again. As water enters these fissures air is expelled from them but in most instances this air can find a path out of the film with no ill effect. In nature these same forces are responsible for moving water from the roots of a tree up to the uppermost leaves. When water based paints are applied to this cracked surface strong capillary forces move the water into these fissures. Usually these tiny cracks in the mud will not even be visible to the eye but they will contain a significant volume of air. Extreme cases will resemble the mud cracking of a riverbed. Under low humidity drying conditions, drywall mud and skim coat will shrink to such an extent that tiny cracks will form on the surface. We believe that the blisters are formed with air that escapes from tiny fissures or cracks in the skim coated wall below the layers of applied paint. I’m pretty sure that every experienced painter will know if he or she is applying foamy paint. This type of blistering differentiates itself from more common paint foaming in that the source of the air producing the blister does not come from the can of paint, or from the agitation the paint receives during application. The primer coat produced no blisters and neither did the first coat of topcoat.Ī unique characteristic of these types of blisters is that they appear to be under a lot of pressure and, if they are left to dry and then cut open, you’ll find that the air bubble has lifted all the coats of paint off the wall, including the primer: The back of the bubble film will be white (the primer colour) and you’ll see clean drywall compound on the wall surface. ![]()
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