Paint coming off the bloody wall!

Old property? Potentially damp wall? Has the plaster been sprayed with silicone? Does it have to look "good"? If not maybe undercoat with SBA??

It's an old property but was refurbed a few years ago, beyond that I don't know. There's no damp.

It doesn't have to look amazing but needs to not look a bag of..... but i'm not spending 10 quid per litre on acrylic based paint!

I'll get as much off as I can scrape off and attack it with PVA* before painting, or would lining paper be better?

• Suggested by a decorator in the family, but I thought that was a no-no?

That's what Leonardo /should/ have done, or the Last Supper wouldn't be such a mess.

Is the plaster actually plaster or an alkaline lime material. I have had bother with that in places in my old Victorian building. But it was more that the paint would cure OK at first and then gradually blister off.

pH test or litmus will show if the surface is strongly alkaline.

I had a similar problem painting a modern extension. No idea what caused it (maybe the (crap!) plasterer over-polished the plaster) but the solution was to spray the problem areas with stain stop and then paint them normally.

and red cabbage juice can be used as a pH indicator.

For problem surfaces you can always paint a layer of oil based undercoat on first, solves most problems.

NT

Or try shelac alcohol base as a first coat then ucoat