DIY Doctor UK DIY Forums

My house is ex council house and I bought it 2 years ago. The walls were all painted a Matt cream before we bought it. The lounge we painted no problem. The bedroom we had to do ALOT of prep. Her dogs had scratched the walls and were lots of holes so spent a long time filling and sanding. Then we followed online guides on painting. We washed the walls down. Did a mist seal coat all no problem. First coat of the silk paint and it’s started to bubble all over. We have striped the bubbles back to where they have stuck and we have been working on this room weeks so desperate for help. Does anyone have any advice on what we can do? Apparently in ex council houses a chalky type paint was used but we did so much wall sanding and cleaning there was hardly any paint left on the main walls. We ideally don’t want to strip the whole wall as it’s cost us a lot of time and money more than we wanted already. We had no problems downstairs but now just don’t know what do do. We prepped everything properly how recommended and now our paint is still ruined and now stripped back to big patches. Can we fill over this and paint again? It’s not damp walls. It’s not new plaster and these seem to be the main reasons I am finding online for bubbling. Any help appreciated!

Reluctant novice painter here encountering a similar problem in our 1970s house trying to cover very old, thick, dark blue - possibly - vinyl emulsion (which I've had to sand back to bare plaster in places) with water-based matt.
Research online suggests bubbling is probably down to an adhesion problem with original paint. I used Wickes plaster paint as a first coat to ensure any of the bare plaster exposed was sealed so I've ruled this out as an alternative source.
Solution suggested in Screwfix forum is to strip back the affected areas to remove imperfections/fill, etc. where needed and then paint with either Zinsser Bullseye 123 (water-based) or Zinsser BIN Shellac to seal the layers below. BIN is the 'nuclear' option; covers anything & everything (like nail varnish!) but it's oil-based so it'll need to be well ventilated, your brush/roller will be a write-off & it's pretty expensive... but then so is 4-5 coats of emulsion when you've scraped it into the bin!
I'm going with Bullseye 123 on mine & will try to update this post with the results.
Incidentally Zinsser CS staff provide really excellent, detailed responses through Screwfix products' Q&A tabs - worth checking them out.