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Hi

I'm just washing my walls down ready for painting and I notice the old paint has started to bubble (see attached). This is an old place with poor air flow so I have had issues with surface mold in this area in the past, no surface mold this time though. Could this be all it is or could there be a more serious damp issue?

Any advise welcome
Thanks

Might be painted over old distemper (before modern paints chalk powder and size breaks down over time) carefully scrape off a patch and see if there is a chalky residue left. if so you may have to strip the lot as the undercoat is not stable.

Coild also be pva used as a primer or wallpaper paste residue. Either way scraping / sanding off the old paint is the first step, then try damping the wall, it shouldn't feel slippery, if it does then you'll need a decent primer. Get back to us if that is the case.