# Second topcoat blisters over clean skim coat



## norepeat (Sep 6, 2011)

Hi all,

I am having a rather irritating problem with paint blistering/bubbling over skim coat. Here's the situation:

I recently moved in to a fairly old condo that has a mixture of drywall and concrete walls. All have been painted with several layers of what looks to be semi-gloss oil-based paint (given the age of the building, probably containing lead). There is a subtle texture to it, a little like the skin of a citrus fruit, which I assume has come from the painters not skim-coating the drywall prior to painting and/or from using a rough roller. I do not like this texture, but do not want to remove the paint (lead!) or drywall (it's in good condition).

To get rid of this texture, I cleaned a wall, gave it a very thin layer of skim coat (ready-mixed finish compound, just enough to fill in the depressions), allowed a couple of days to dry (no excessive temperature or humidity) sanded it, vacuumed and wiped thoroughly with microfibre cloths to completely remove all dust. I then primed with Benjamin Moore Natura acrylic latex primer and let it dry for a day. No imperfections. I then put on a topcoat of Benjamin Moore Natura eggshell and let it dry for a day. No imperfections. Lastly, I put on a final coat of Benjamin Moore Natura eggshell and within minutes of finishing lots of small bubbles/blisters appeared. They aren't huge (2-5 mm across), but they are noticeable if there is even a small amount of sidelight. They have shrunk a little as the paint has cured, but they are still there and appear to have lifted all the paint off from the skim coat (if I paint a wall in the same way without the skim coat, there are no bubbles at all). So:



Why is this happening, and if it is a skim coat adhesion issue then why does it only happen on the second topcoat?
What can I do to prevent it happening again? I am fairly certain that there is no more skim coast dust to wipe off.
If this is going to happen regularly, is there a way to smooth out painted walls without using skim coat?
I have seen a few discussions on this issue, but don't have the dust/moisture problems that other posters seem to have. Any insight appreciated!


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## Brushjockey (Mar 8, 2011)

I used to get this with the old regal long ago- and I really tried to figure it out. Somewhat unsuccessfully.
I see you are trying to go no VOC with Natura, but particularly with primers, If they take all the good stuff that works out of it to qualify, there is not automatically new chemicals that work as well. 
A better/ more effective primer might have made a difference. 
Sounds like you did everything right though. 
What sheen are you using?
One fix might be to scrape off bubbles, spot prime with Zin 123,or BM fresh Start- mud /sand smooth, reprime and then see if you can spot touch up. If there are lots of them on a wall, do a section to see if you have success, then you might need to rrecoat the whole wall. 

Bout all I got.


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## chrisn (Dec 23, 2007)

Brushjockey said:


> I used to get this with the old regal long ago- and I really tried to figure it out. Somewhat unsuccessfully.
> I see you are trying to go no VOC with Natura, but particularly with primers, If they take all the good stuff that works out of it to qualify, there is not automatically new chemicals that work as well.
> A better/ more effective primer might have made a difference.
> Sounds like you did everything right though.
> ...


 
bout all there is:yes:


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## jsheridan (Jan 30, 2011)

I've experienced this rather frustrating problem myself and, like Brush, I've never known why. I would let the walls thoroughly dry, week to 10 days, a lot of the blisters will disappear on their own. what remains can be sanded lightly, spot with spackle, prime, then finish. If you can get away with spot touch up, try that. I've done full recoats of walls, after all the new prep, only to have new areas blister. I never had the week or so to allow the walls to dry, but the issue is the water, the vehicle, in the finish penetrating/activating the previous coats and vaporizing. With the extended dry time, it may be cured enough to resist the activation, can't say for sure. But, be careful recoating a whole wall sooner based on my experience.


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## ltd (Jan 16, 2011)

possibly your rewetting the skim and it is pulling up .when your rolling over the skim roll and make good contact and move on do not go back over it .i have had this problem over the years with quick setting mud and ever time i roll am looking out the corner of my eye to see if those dang bubbles are their .some times you can stick a corner of a razor blade in them and push them back in. in other words like the other guys said/ you got me . i would love to have an answer i have even called sheetrock durabond rep .and i lot of good that did:huh:


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## jsheridan (Jan 30, 2011)

ltd, I had a lot of problems for a while with blistering, and no one could tell me why. I stumbled across the answer somewhere on line. I was using three coats of 45 mix for patching and it was the plaster in the 45 that was giving me problems. The man with the answer had the same problem, and he said go two coats 45, final coat with blue lid. Solved his problem, and mine. However, I still have an occasional problem as OP.


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## Windy Painters (Sep 7, 2011)

*Lack of primer*

Always use primer before skim coat over problematic areas. Especially over semi-gloss, chalky surface, after wallpaper removal.


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## norepeat (Sep 6, 2011)

Thanks for all the replies! Sounds like it's something that can't be 100 % avoided, but I will try priming walls before skimming (I've been using the bluetop CGC all-purpose ready-mixed drywall compound) and seeing about a more effective primer to go on top of the skim.


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## jsheridan (Jan 30, 2011)

Norepeat, that's an appropriate name. As a pro, if I was having that much problem, and I had a lot more walls to bite my nails through, I would consider going to Zinsser Cover Stain oil primer. This would put an oil barrier between your finish and the joint compound, and would probably solve your problem, but any more I really don't have much faith in anything in a can labeled paint/primer.


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