MegaSack DRAW - This year's winner is user - rgwb
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We had a lot of our house re-plastered recently and since it's dried out we've been going through the laborious task of painting it. Now this is throwing up some problems. Firstly I know how to paint fresh plaster and secondly I asked the plasterer what his recommendation would be on the best approach. He even checked it was dry before we started painting.
So a mist coat has gone one, 60/40 paint/water using contract emulsion (what the guy said to use). A second coat of that has gone on, watered down a touch, so maybe 90/10 paint/water.
But, we're getting a weird textured effect on the surface in a very noticeable part of the lounge. The area in the picture is painted with a a good quality roller.
I've tried to contact the plasterer about it and he's not responding, which is annoying. I've sanded it down gently with 240 grit paper to a smooth finish, but when you paint over it again the textured surface comes back.
Any ideas on what is causing this and what can be done about it? I've painted a fair bit of fresh plaster in my time but never seen this. Have they done a poor job or is it something else? I'd really appreciate your help as I'm stuck as to what to do.
!!!
Presuming the plaster is smooth before you paint, I can't really see how it's his issue (might be wrong though)
Have you tried a different paint?
Does the paint flake off if you scrape at it?
I am currently painting a lot of fresh plaster in our house and have done pretty much exactly the same as you, And in a few spots the top coat (trade endurance emulsion) has ridged and flaked off. I am not sure why either, possibly wasnt quite dry? or some residue of something on the plaster? either way last night i sanded it back to bare plaster in the affected areas and tonight will try again. If that works i will report back that sanding back is the fix. I have also cranked the heating up if it isnt quite dry. ( the rest of the room has been fine just a few isolated spots)
The plaster is smooth yes. Dry and clean too. The paint doesn't flake off if you scrape it but when you paint it on here it forms this odd texture. Which comes back exactly the same after you sand it back down and then re-paint it!
So I'm not sure how it can be the paint, or the roller. There are a few other spots in the house where it's happening too but this one is the worst.
weird?!?, we had similar in our old flat where there was something left on the walls from the glue used to stick the old wall paper on in the 60's that although sanded smooth when you painted the pattern from the paper would appear in the paint, in the end had to get it plastered (which is weird as you are obviously already on fresh plaster) another option at the time was breatheable paint
could it be salt coming out of the plaster? Would a layer of pva or brick sealer stop the paint being bubbled?
Contract emulsion (which we used) is breathable. Or that's what i've been told anyway.
I'm thinking of getting some kind of sealer as I'm going round in circles here and it's driving me mad. I'm certainly not planning on putting any PVA on though. I've been led to believe that just causes other headaches.
How long has the plaster been up? Are you sure it is properly dry? It takes ages, well beyond when it looks dry
Plaster has been up for weeks, almost a month. The plasterer who did it confirmed it was OK to paint before we started.
Is it contract matt? Contract silk isn't as good on new plaster
I'd use a coarser paper to rub down, but don't go mad and scratch the surface
Looks like the pva used by the plasterer is being re wetted and reactivated by the paint in that area.
I'd sand back and feather out the edges, dust and clean down and apply a coat of zinsser gardz.
Allow to dry and then coat up the areas again with your contract matt.
Give all the walls a light sand over and clean down to check for any more problem areas before applying your top coats
I was going to ask what brush had been used on the walls, because those look like brush marks to me. I had assumed that the brush was contaminated with something that is causing this but the pva suggestion above makes sense. Specially if it was put in with a brush. When you sand wipe down with a very very lightly damped cloth in case some contaminated dust is being left behind.
i do quite a bit of plastering, there is no reason that the plasterer would of used pva on top of the skim coat only under it if the background was to dry like dried out bonding. can't see how pva under the skim coat would have that effect, its covered by about 3mm of plaster.
not something i have experienced in over 25 years of plastering.
I was meaning that the plaster could of been overworked in those areas bringing the pva nearer the surface. If the mist coat is soaking in like it's supposed to then the water is reactivating it just under the surface. It looks like contamination from something or other though even if it turns out pva isn't the culprit!
I've managed to get hold of the guys who did it who are coming round tomorrow to take a look. Will something like that Zinsser stuff stop it happening again? Either way I'm going to be sanding it back once again so I just want something to definitely stop it reappearing!
Yeah zinsser gardz is a very useful in the right circumstances. The spec sheet is on the zinsser website. You shouldn't need a lot if it's just small areas of the walls with problems.
Could it be a patch where the mist coat has dried funnily or not been worked in fully when applied?
That looks like poorly mixed emulsion & water...normally dries flat though.
My money is on pva residue .
lots of sanding .
Been there.
🙁
edit- just looked closely at the finish- did you put the paint on with a filling knife?!
🙂
Same problem in my place about 20 years ago caused by over troweling on all the masonry walls, stud walls were ok. I used a white sprite and oil based undercoat mix and it was fine, not the idea breathable coat it should have had for new build but 20 years on its all good. I think in the trade it’s called mapping.
That looks like poorly mixed emulsion & water…normally dries flat though.
I promise you that it was mixed properly. I'm very thorough about such things. Doesn't explain why the pattern returns when I sand it down and then repaint it!
Paint was put on with a decent quality, brand new roller.
Exactly what paint have you used...?
It looks like what happens when you paint over acrylic paint with cellulose (or the other way around, can’t remember!).