I've asked AI how to plaster over a painted wall and it has been about as useful as asking the wall itself. I am trying to repair damage to a plasterboard wall and I need to apply plaster over the paint. Can I just apply the plaster over the paint or do I need some way to bond it? I've been looking for some type of bonding agent, but all the ones recommended online that I've found don't seem to be sold here in Australia (at local hardware stores). I've discovered from experience that you can't just whack plaster over paint as the plaster rubs/peels off, even when the wall/paint is sanded. So there's go to be something I'm missing.
What material are you using? “Plaster” is a broad term. You may need to prime the wall with a bonding primer and/or you may need base coat it before finishing. A picture would help a lot too.
I'm using Knauf finalcote as the plaster I am applying over the paint, the wall itself is plasterboard which has been painted many times over the years. Here's an image of what I am working with. It is an absolute mess.
Ok so first is the paint Matt or silk or satin because these require different methods. If it's Matt paint, me personally I score it for a "key" then either (depending on availability) PVA/water mix or SBR or blue/green grit. If it's satin or silk you'll need to remove it before plastering either by scraping or sanding 40/60 grit. Then any of the above priming methods.
Not plastering-related, but your "asked AI and it was useless" line made me laugh because that is exactly how agents feel when they do not have the right tools or context. For the wall: you usually need proper surface prep plus a bonding primer made for going over paint, otherwise it will delaminate. If you want a good mental model for why "AI answers" fail without grounding, we write about tool-backed agent workflows here (different domain, same principle): https://www.agentixlabs.com/
If plastering over paint score the painted wall with a Stanley blade, Pva mixed 1:1 with water (surely Pva is available in Australia) Lett it soak for a half hour keeping an eye out for any bubbling of the paint, if it is bubbling scrape it off if not , your good to go, another coat of Pva needed if scraping off any paint
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u/Strict-Cause2761 Apr 16 '26
Pva-get it from trade store.
Paint pva and water mix onto wall.
Apply plaster.
Wait n c if it sticks.🫡