Hot Topics: Painting Over Blistered Paint Hot Topics: Painting Over Blistered Paint

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When paint starts peeling off, do you have to strip the whole surface before adding a new coat? As always, our forum of seasoned DIYers and pros has some advice.

Original Post: Repainting project but old paint is blistering

mktbully Member

Hello, paint gurus. I need some advice here on how to tackle my interior repaint. The house was built around the 1930s with plaster walls. It's probably been repainted a few times throughout the years.

The last time I painted it was about seven years ago and the old paint was in good condition, so I rolled on latex paint and all was good. Recently, I've noticed that the paint on the ceiling is bubbling up. It's occurring in multiple places in patches and it seems like the old paint underneath is losing its bond.

So what do I do at this point? Do I have to strip the layers of paint before I apply a new layer? I'm pretty sure there was leaded and oil-based paint on the walls at some point. Do I just scrape the loose stuff and prime and paint and hope the rest won't flake off?

marksr Forum Topic Moderator

First, you need to determine why the paint is peeling. The most common cause is moisture so you need to make sure there isn't a leak. Water stains are normally darker than the surrounding paint. It's also possible that the underlying paint didn't have a good bond and the weight of additional coats of paint caused it to fail. Is the paint peeling all the way down to the plaster? In what rooms is the ceiling paint peeling? Kitchens, baths, and laundry rooms are generally painted with an oil-based enamel which requires priming before top coating with latex, but the rest of the house would normally have been painted with flat oil, which usually doesn't need priming. I'd scrape off the loose and skim coat those areas with joint compound. If you contain the debris and don't sand, there shouldn't be any issues with the lead coatings. While some lead paints 40 or more years ago were lead based, latex paints are not. Is My Paint Latex Or Oil?

mktbully Member

There's no signs of moisture at these areas. No discoloration whatsoever. It does look like it's going down to the plaster. The rooms are dining room and the den (TV room).

Any idea how to prevent this from occurring in other areas, or do I just have to keep patching and painting these areas as they blister out?

marksr Forum Topic Moderator

When walls are that old, there isn't a lot you can do other than keep a stable environment (constant temp/humidity).

stickshift Group Member

My two cents would be to scrape off what you can, make any needed repairs with joint compound, prime everything with an oil-based primer (on the assumption some of the remaining paint it oil-based) and then reapply your latex paint.

mktbully Member

Can you recommend what type of primer I should be using? I've heard alkyd primer should be used.

marksr Forum Topic Moderator

Alkyd is another name for oil-based. I'd try to determine what the existing paint is before resorting to an oil primer (not that it hurts to use oil).

mktbully Member

The surface layer is definitely latex since I rolled it on years ago. It was white before I rolled on another white so the paint is not separating from that. The back layer where it's blistering away from the wall is unknown since I can't pull down a chip big enough to test. The paint chip that I pulled down has a tan backside, so it's not the paint that I rolled on that's blistering off. Should I break out a Q-tip or something and test the paint on the backside to see if it's latex or oil?

marksr Forum Topic Moderator

I would scrape off all the loose first, and then test the paint with denatured alcohol.

To read the rest of the thread, look here: //www.doityourself.com/forum/painting-staining-all-interior-exterior-surfaces/581570-repainting-project-but-old-paint-blistering.html

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