Plaster peeling off when painted

[JumpJockey]

We had a bloke do a lot of work at the end of last year, part of which involved plastering the hallway ceiling and a section of wall by the side of the staircase. The bit of wall that needed doing was over where a pipe was taken out, a long strip about a foot high I guess. He plastered about 4 feet height in all above and below the repair, and it looked a bit crappy round the edges but we thought Oh well when we paint it will be less obvious.

Having finally got round to it, I put a mist coat on to seal as per instructions. Then put the normal paint on, with a roller. All the way round the edges where the plaster is thin it started to peel away from the wall, picked up on the roller and stuck itself down somewhere else, basically leaving the wall looking like it's covered in scabs. Very hard to neaten, and I started to try and tidy up the edges. It's now all just coming off in sheets. I've peeled away as much as seems to want to just fall off, and the bit at the centre where the repair is, is a good 4mm thick above the height of the rest of the wall.

Bar sanding it all down so at least it's a gentle incline to the thick part, and putting pictures along the length of the raised bit, is there anything else we can do to make it look less shit?

If you have some PVA glue put some in a bucket and dilute with water at a ratio of 50 parts water:1 of PVA. Brush onto the fresh plaster and allow to dry. Then put a coat of paint diluted 1:1 with water. That hopefully should cure your problem.

It sounds as though the plaster is still damp - was the pipe sealed properly. I'm no expert but the only time I've had this is when there was a leak and the wall was damp :(

Cokemachine - since it was a gas pipe, and he did the work in December, I blimming hope not!
NicholasT - I've already put the mist coat thing on and that seemed to dry fine, it's just the thicker emulsion that's the problem. I've got rid of most of the really thin stuff round the edges, I guess the main concern is the fact it's so thick now and I've not yet touched the ceiling with actual paint. Will give the glue business a try on that just in case.

please don't ever put PVA on a surface you later hope to paint.

It prevents the paint soaking into, or even touching, the substrate, and as PVA is water soluble, it softens and tends to bubble under emulsion.

PigletJohn - why do people recommend doing that, then? I did a quick google and it does seem quite a common thing to say.
I've done some more sanding of the stuff that was coming off and it turns out that the render (?) he used to fill the hole is the part that's 3mm above the rest of the wall, he must have used all the skim plaster to try and discreetly make it look flush. Except it didn't work .
Is it safe to sand down the render stuff and get someone to replaster? Should we be asking him to do this, since he arsed it up in the first place, or is 4 months too long and should we not trust him anyway? Grrrrrrrrr.

the thin (feathering) might have been overwatered, or maybe the wall was dirty or painted, or had traces of wallpaper paste on it, or maybe he should have roughed it up, can't tell. It's OK to use PVA on old walls or bricks to help plaster or mortar stick to them, but not under paint. Ask a few people who are painters.

My guess is that he was not a very good plasterer, so I'd try to find someone better. A good one will skim over the entire wall in about as much time as it would take to patch up the damage. He will probably charge about half a day though, however small the job.

Sanding off plaster is a very slow, dusty and tedious job. I'd hack it off. You can try a broad metal scraper for anything loose, but I expect you will be left with a lumpy finish. If you can get a recommendation from friends or neighbours of a good plasterer, ask what he recommends. It may be that the pipe projects above the surface of the existing plaster so needs extra depth to hide it.

I agree with PigletJohn, it sounds like it was a bad plasterer.

I have had the experience of 3 different plasterers, one of which left the walls as smooth as glass, pity he retired. I have had half a house done, one room and then a garage conversion with a door knocked through where he patched. It was all very well done.

Never put PVA on the walls, my sister was told to do this and had lots of problems trying to paint it.

All 3 plasterers told me to just mist coat it.

Either get the original plasterer back to see what they have to say for themselves or get another plasterer round to see what they suggest. Try to get someone recommended as some plasterers are fab but leave a hell of a mess. My retired guy seemed to take forever to do an en-suite but he cleaned up too so he can take as long as he likes

He turned out to be a bit of a bodger in several other areas too so it doesn't surprise me. As far as we can see the plaster was just put on over the existing painted wall around the repair, so without any preparation of the surface. Presumably that's why it just falls off. We already had to get someone in to redo the shower room he buggered up, and we made him pay for this, so I doubt very much he'd even answer the phone if my number comes up!

I'll ask the neighbours to recommend someone then, and get it done properly, meanwhile out with the large pictures :) Hopefully the ceiling should be ok, that was boarded over and then skimmed to tidy the edges. Fingers crossed!