Mist coat did not adhere. PVA related or wrong miscoat product?

What went wrong PVA was used before plastering: PVA (polyvinyl acetate) is often used by plasterers to help the new plaster stick to old painted walls. However, if too much PVA was applied or not diluted properly, it can leave a slightly shiny, sealed surface on the plaster once dry. That shiny layer stops paint (even mist coats) from bonding — so the paint just sits on top and peels off, exactly as you’ve seen. Mist coat wasn’t the issue: Your 60% paint / 40% water mix was fine. That’s a normal mist coat consistency. But because of the PVA barrier underneath, the mist coat couldn’t absorb into the plaster. 🧰 How to fix it Remove the flaky paint: Scrape off all the loose and flaking paint using a broad scraper or sanding block. You may need to sand back quite a bit until you reach solid, well-adhered plaster. De-grease and clean the wall: Wipe the walls down with warm water and sugar soap (or mild detergent) to remove dust and any PVA residue. Let the wall dry completely. Key the surface (optional but recommended): Lightly sand with 120–180 grit sandpaper to create a slight texture for better paint grip. Seal properly this time: Use a breathable sealer such as Zinsser Gardz or Dulux Plaster Sealer, not PVA. These products are designed to stabilize chalky or PVA-contaminated surfaces and help paint adhere. Reapply mist coat: Once sealed and dry, apply a proper mist coat again (70% paint / 30% water), then proceed with your top coats.

PVA shouldn't be used over new plaster it will create a film over the new plaster so any mist coat won't adhere properly. I'd check with the plasterer what he used the PVA for? You're correct on the mist coat though, just don't use contract matt - a vinyl or durable matt will adhere better. Hope this helps.

To get the best results for plastering , you should use a pregrit to make sure the plaster sticks really well to the walls . Mixing water with paint can be used but getting a contract matt mixed with 20% water should be better . Main question is why did they use PVA before plaster ? Worth checking with the plasterer if or why they used it . Also if the price was very low (like £300) to plaster the room , it also indicates the experience and knowledge of the tradesman . Worth checking with the plasterer to see exactly what happened . Paint like dulux and below , are likely to come off onto the masking tape . Any other brands like Lick , F&B , little greene will not come off with the tape . Hope this helps

Regarding the plaster they did right by applying PVA to painted surfaces. Also you mentioned you applied a mist coat, now mist coat is fine with mixture you did. Most people don't think about sanding the plaster lightly before applying paints. Also you mentioned dulux. What you should be buying is an emulsion for new plaster as most paints have traces of plastic in . Also the masking tape that you used should be a low tac tape that won't peel paints off . Hope this finds you well . Good luck 👍

This is a very common issue and, from your description, it is almost certainly PVA-related, not the mist coat ratio itself. PVA is often used by plasterers to help new plaster bond to old painted surfaces. However, if too much PVA is used or it is left to dry glossy, it creates a sealed surface that paint cannot properly adhere to. When a mist coat is applied over plaster that has been sealed with PVA, the paint sits on the surface instead of soaking in. This is why the paint is flaking off, especially when tested with masking tape. To fix this properly: • Scrape back all loose or flaking paint • Lightly sand the surface to remove any remaining sheen from the PVA • Apply a proper stabilising or bonding primer designed for problem surfaces • Once dry, repaint with your emulsion coats Reapplying a mist coat will not solve the issue while the PVA layer remains. The surface must be keyed and sealed with the correct primer before repainting