Weird Bubbles in Drywall Mud

DrHicks · 10-31-2011, 01:29 PM

I'm replacing some water-damaged drywall in the family room of a rental house. The sheets were installed horizontally, so I made the cut at the 48" line, installed a new sheet of drywall, taped & mudded the new seam. Pretty straightforward.

During the process, some of the mud I'm skimming on the "old" drywall has immediately developed tiny little bubbles - kind of the size of pimples. It didn't matter how many times I wet over it, they immediately reappeared. It was very random, where these bubbles appeared.

I eventually rolled on some GARDZ primer, went over it again & got on with business - so it's now done.

But what the heck was causing that? I've never had that happen before.

Did I not adequately scuff the (satin) sheen of the paint on the old drywall? Was there some sort of contaminant? If that's the case, why so random?

Just wondering what you guys' thoughts were. Thanks!

boman47k · 10-31-2011, 08:47 PM

I think most will say mudding a painted wall was the cause. I am not sure that is the only possible cause.

chrisBC · 11-08-2011, 03:53 AM

if it was "fisheyes" - I've seen this from the mud being put on too thick, or not being mixed well. Kind of hard ot say for sure without seeing it.

**oh'mike** · 11-08-2011, 06:26 AM

I've seen that over a painted surface too---rather common----Sorry I don't know why.

DrHicks · 11-08-2011, 07:56 AM

Thanks for the replies, guys. The wall is finished and painted now - all is well.

It was just such an odd and random thing. I've seen bigger bubbles before, but these were (maybe) about 1/16th of an inch. And very random. 15-20 in one spot, then none over most of the rest of the surface.

This is a rental house that I bought 4 years ago. It had a mold problem that we eradicated. I wondered if maybe there were some lingering mold spores on the wall, but the paint I was mudding over was applied after the mold was taken care of.

Weird...

Thanks again guys!