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It looks like my joint compound is bubbling up?

It looks like my joint compound is bubbling up?

Old 04-03-17, 08:57 PM
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It looks like my joint compound is bubbling up?

Hi everyone - I was applying a second coat of mud to my new drywall tonight. Most if it went on just fine but there is one section that I cannnot get to be a nice flat texture. When I run the knife over it, right away it looks nice and smooth but then seconds later, it looks like it has these little bubbles in it - hopefully the picture helps but it's hard to see. What would cause this? How do I avoid it? And can a third coat fix it? Should I sand it when it's dry before a third coat? Thanks as always!

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Old 04-04-17, 03:19 AM
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It looks as if something oily was splattered on the wall prior to your mudding. If the mud is dry, try sanding it down with a sanding block to see if it either chips out or becomes smooth. If the former, then you may need to apply a primer before you add coats of mud to seal in whatever is causing the bubbles.
Old 04-04-17, 03:40 AM
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I'd probably take a drywall knife and use it to 'scrape' off the high spots before sanding. I agree if more than the high spots comes off there is a contaminant on the drywall that will need to be dealt with.
Old 04-04-17, 04:01 AM
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If using a pre-mixed compound, it has a little air in it. Work in in the pan before applying to the wall. When you do your final pull, the knife needs to be completely clean before each pass. I agree that you can run a knife over it before sanding and then fill in the bubble holes with a very thin coat.

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