Kinda a question like Tom Bainbridge asked...

[Spike!]

bubbles in mud... If I understood Toms thread it is caused by skimming or taping over a painted surface?
I'm skimming and repairing some walls for my folks in FL and I'm filling the deep stuff with DB45 then top coating/skimming with Sheetrock lightweight low dust mud.

Lots of bubbles... or pocks if thats the more correct term.

Anything to do that can help?

Thanks

[Bill from Indy]

mud over quickset of any kind, that I have used anyways...from usg/lafarge/gold bond...will pit/pock/bubble if it is not DRY...I don't mean hard to touch..I mean dry...you can get away with skimming tight over quickset but if you have to have any type of build/float at all, it will bubble..it is the chemical reaction in the quickset similar to skimming over paint..kinda like what Joe said in the other thread, the air is forced to the top as it dries and causes the pocks/pits..its just part of it..be it a chemical reaction to the quickset or the fact that the wall is sealed with paint and there is no where to evaporate because it has to do it at surface instead absorption..usually a 3rd coat or what I call a rake coat is needed..put it on and pull it off...changing direction helps some, but it don't eliminate the issue