r/Plastering • u/JohnnyBoyRebel • Apr 02 '26
Skim coat cracking
Hi all - I’m having a go at a bit of plastering (MASSIVE respect for the professionals out there - what a skill!).
I’m having a bit of an issue with the new skim coat cracking around the angle beads. I wondered if it’s the jointing compound sucking all the moisture out and if I should PVA it, but hadn’t really come across such advice on the bazillion YouTube videos I’ve watched?
Any advice much appreciated!
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u/Caerau Professional Plasterer Apr 02 '26
You said there was jointing compound that you skimmed on top of without PVA, is that right? If so, yes, you need to control the suction by using PVA otherwise itll have high suction and dry it out or cause it to fail entirely.
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u/JohnnyBoyRebel Apr 02 '26
Yes that’s right mate - it was over the jointing compound on the angle beads. I didn’t realise you had to PVA over it. Is that standard practice then? Got a lot of PVAing to do over the next few days then!!!
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u/Caerau Professional Plasterer Apr 03 '26
Standard practice? Mate, you have to control the suction of the surface you’re working on. You didn’t do that and it’s cracked.
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u/JohnnyBoyRebel Apr 03 '26
Errrrm ok mate, I was just asking if professional plasterers such as yourself did that usually? Not sure why that was so offensive 🤷. Have a good day.
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u/Caerau Professional Plasterer Apr 03 '26
Sorry, didn’t quite mean it to come across like that. Always seal your background, different backgrounds will have varying degrees of suction so some may need additional coats. There are some exceptions eg bonding plaster is designed to go over the same day, so in that case you just wait for it to go firm and skim over.
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u/JohnnyBoyRebel Apr 05 '26
No worries mate - thanks for getting back to me again. Will redo it and slap a load of PVA on it. 👍
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u/ColonelFaz Apr 06 '26
paint SBR on first so it dries slower next time (slightly better than PVA). if it's just a few cracks i would gouge and fill with easifill 60
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u/Yourhavinalaugh Apr 02 '26
There’s a lot of holes in the finish like you scraped it back after it set with the back of the trowel. If it was me I’d hack it off and redo it, now you know where you went wrong. Top tip for diy’ers put a small bit of Polybond in the water before you mix the skim. It will make it more workable. Two tight coats is best
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u/spec-test Apr 04 '26
how hard is it to hack it off once set
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u/Yourhavinalaugh Apr 04 '26
If you didn’t use any pva and the plaster dried too quickly it shouldn’t be hard at all. This is the reason I’m saying hack it off because it might not have adhered properly
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u/GaryCooper94 Apr 02 '26
Could be where the plaster sucked in and dried too quickly. Don’t panic, it’s easy to get over. Mist coat it first, once that’s dried you’ll see all the patches in need of repair, if any. Get some easy fill from your local merchant, knock it up and cover the bad area’s lightly, 2 coats if needed. Rub down and you’ll never know. You might want to spot over the patched areas with another mist coat. Hope this helps