We had to do some repairs to some walls, putting up a few sheets of new
drywall. We used Durabond setting type drywall compound, both all-purpose
and then lightweight. We used Conco PVA primer/sealer and Pittsburg latex
paint sprayed on with an airless painter. A few hours after painting we
went back and found several spots where the setting type lightweight
compound turned soft and bubbling up, but only over the old, smoke-covered
walls, not over any of the fresh drywall. We also found a spot where no
work had been done, but it is bubbling up too. We have more painting to
do
and don't want the same problems. Any ideas on what happened and how to
prevent it? Thanks.

--
Mike D.

You primed how long after the compound was applied? And was the primer
fully dry before you painted with topcoat? Check instrutions on both the
primer and the compound. I've had bubbling up from either not waiting long
enough for first coat to dry, or by continued degassing of the plaster
compound as it sets - I think it may be the latter. Thicker areas of
compound can take a day or so to set up, depending on humidity, at which
point it turns from dark and pliable to a sort of fully bleached , white
look.