Painting the interior side of an exterior wall. One localized area (about 6 in x 6 in) has bubbled (numerous, small – perhaps 1/8 – 1/4 in diameter, separate).
There is nothing unusual about this section of the wall. It has fiberglass insulation and vapour barrier. The area is mid-stud; it does not straddle a stud. There is no junction box, etc. Outside is not remarkable either – sheathing, vinyl siding, etc. No dampness/moisture is present. I should note that the paint alone has bubbled; there is no suggestion of crumbling drywall, etc.
Paint is top quality acrylic latex.
Site has been painted before: builder’s primer, one coat of flat-finish acrylic – no apparent problem. Subsequently repainted with two coats of flat finish latex – again, no apparent problem. Brings me to the present.
When I applied the first coat this time (flat-finish acrylic) it dried with bubbles. I did not notice it until the next day so I am uncertain exactly when the bubbles formed.
Scraped off the area to the original gyprock surface. Built surface level with spackling compound. Allowed to dry overnight. Sanded smooth. Primed, 1 coat. Applied the first of two topcoats. Same area bubbled.
Have scraped and re-spackled. What now?
Thanks for your help.
Since it's been painted before, it implies somebody has lived there.
Any chance that they sprayed silicon something or other on boots or hair or something and the overspray hit the wall there? Or even just kids goofing around spray something on the wall accidentally?
Welcome to the
Taunton University of Knowledge FHB Campus at Breaktime.
Excellence is its own reward!
So the primer didn't bubble, but the 1st top coat did?
Did the paint separate from the primer? That doesn't seem likely. If the primer separated from the surface below, then try an oil-based primer before painting again.
My best guess is that that there's a layer of weak joint compound (eg. too wet during application or it subsequently got wet) that's actually separating when you paint. The primer alone may not cause it to bubble because primer is generally much thinner than paint and doesn't keep things wet as long.
What do you mean by "gyprock"? More likely it's plaster or drywall. But if it's actually gyprock, then ignore everything I wrote because I don't know anything about gyprock.
I was thinking along the same lines as Piffin. Try priming the area with Zinsser BIN white pigmented shellac. Then paint as usual. That stuff will seal a slab of bacon slapped against the wall.
Pete Duffy, Handyman
going with the Zinsser. should have thought of it myself as have used it b4. Used "gyprock" to mean "drywall". Correct or not, terms used interchangeably here (southern Ontario).Thans for the help everyone
Just curious how you made out with those bubbles.
I hadn't seen that scenario until just a few days ago. In may case, it was a wallpapered wall. The paper could not be removed (I've seen this TOO many times) so I removed what I could and used an oil primer over the whole thing. I spackled the edges wherever the paper was removed (3 light coats), sanded and primed the repaired areas. This time, I used a latex primer.
Applied the 1st coat of paint and so far, so good. Applied the 2nd coat of paint and I got a several bubbles ranging in size from 1/8" to 1/4". They only appeared where I had spackled, but only in a few places. Most of the bubbles disappeared before the end of the day, but the larger ones were still visible. This was my last day on the job. I told the HO that I would come back the following day to repair them, but they said not to worry about it. There were large pieces of furniture going on those walls and the improvement over what was there before was huge. I have more work there in a couple of months. I'll double-check on the walls then.
I figure that the 2nd coat of paint added enough moisture to soften the spackle since the oil primer behind it was acting as more of a vapor barrier (and therefore, preventing moisture migration) than latex primer would have. By peeling back one of the bubbles, I could tell that it had lifted all the way back to the spackle. If I do this again, I'm going to use an oil primer over the spackled areas before painting. That should help to seal it up better.
I think that's the "cure" and hopefully I'll remember because it may be quite a while before I see this scenario again.
Used the Zinnser & no more problems. Never gave much - if any - thought to the "why it worked."
try sealing area with an oil base primer like kilz, then topcoat
The only time I've seen a wall do that it was moisture, so I gotta ask how positive you are there isn't some in the wall. You couldn't feel it, see it . . . but the paint bubbled. I stuck a pin meter in it and 19%!?!
Worth checking if you have a moisture meter laying around.
Real trucks dont have sparkplugs