Why does old paint bubble when new wallpaper applied on top?

hi you need 2 apply a proper pva primer 2 the wall before papering, scrape of as much loose paint before applying then when fully dry paper over it

pj1
July 2010

I dont think its the paint thats bubbling its the paper.
With any paper you have to make sure every bit is pasted, if you miss any, then that is what causes the bubbling.

Decorating Diva
June 2010

So the paint itself is absorbing water then!

I would guess that the top coat of paint on the wall was applied badly and has not properly adhered to the plaster - likely no mist coat to soak into the plaster and provide a firm base.

If what you say is true - and I have no reason to doubt you - the area of each buble has paper sticking to the paint but the underlying paint is not stuck to the wall.

I have no solution for you - I might personally try a test piece with thinned pva as a barrier between paper and paint - but I'm a dreadful risk taker.

Good luck...

Peccavi
May 2010

thanks Peccavi.

It is the paint bubbling, I've watched it happening with my own eyes, so I don't have it wrong. the problem is that it's really slowing the whole process down and affecting the joins. thanks anyway.

Frustrated Decorator
May 2010

I don't think it's the paint underneath bubbling - I suspect it's the lining paper absorbing moisture - stretching and bubbling a bit - and slowly drying out and shrinking.

Whenever I paper - nearly every time - I get a few bubles that always go overnight - I expect to get a few bubbles.

Paste up the paper evenly and leave it for at least three mins to absorb the moisture in the paste - while waiting you can be pasting up the second sheet.

I'm sure you have it wrong - if the paint were bubbling it would lose its adhesion with the wall - crack and flake - paint doesn't behave this way if you wet the wall.

And anyway - you say the bubbles go away on their own - what's the problem?

Peccavi
May 2010