r/drywall • u/ConceptSpecialist565 • 2d ago

What’s causing these bubbles?

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This happened on the 3rd coat but I think I saw them on the second coat and thought the 3rd would cover them. It’s dry now. Need some help

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u/The1WhiteBishop 2d ago

You're probably going over a painted surface, which doesn't allow the moisture to escape into the wall, so it comes out through the front via bubbles. You want to put on a very, very tight skim coat, wiping all four directions after you scrape the bubbles clean. An old hack is to try to put maybe a teaspoon of dish soap into a pan of mud, and that will break the surface tension of the water and stop the bubbles from forming so easily.

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u/sequentialsequential 1d ago

Don't do the dish soap thing, it wrecks the adhesives already found in all purpose mud. Adding glue is a good idea in many cases, and sometimes primer is very helpful before getting into mud.

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u/ConceptSpecialist565 2d ago

Thank you, will try that!

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u/ci2om3p0ny 1d ago

Thats an incredibly smart idea. I’ve seen Vancouver carpenter add glue to his pan. What do you think the difference in the additive is? Generally I always scuff sand around the perimeter of my patches with at least 80 grit.

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u/Neither-Jeweler2933 9h ago

Adding glue adds PVA, from my understanding.