Advice needed for really stupid painting mistake

[ChakaCarm]

Hi there - not sure if this should be on the DIY Disasters forum but thought (hoped) you decorating experts might be able to help. Many thanks for any advice you can give.

Decorating a small spare room and used Dulux Absolute White Light and Space as a top coat on three walls (over Leyland Contract Matt to save money). All good.

Then painted fourth wall in a Wilko tough matt emulsion deep yellow (one coat, very patchy but loved the colour). Next morning realised that the deep yellow has the effect of making the white wall opposite look really yellow and dingey. (I know - seems obvious now!)
So I decided I would paint over it and have all four walls white. Such an idiot. Without keying the surface, I cut in all round the wall and rolled on one coat pf Leyland contract. V v patchy but thought it would just need more coats. When I went to add another coat the roller is basically peeling off the first layer of white which won't adhere to the yellow Wilko paint underneath. I tried putting on a thicker layer - with a brush - and it adhered a bit better but I think I could probably rub it off with a paper towel and not much effort.

So my question is...what do I do now?! Should I try to wash the paint off the wall? Or sand the wall with a pole sander (I'm thinking the sandpaper will become clogged with the contract white without keying the surface of the yellow paint)? Or would some kind of primer go over the white and bond the two paints together? I have some Zinnser B-I-N I was going to use to undercoat the skirting boards and architrave - would that work?

Really grateful for any help you can give.
Thank you so much!

 

[opps]

Contract paints are often designed for new (slightly damp) plaster.

They are NOT suitable for recoating, that said, many supposed "decorators" use them for that, presumably because the paints are cheap and they do not understand the potential risks involved.

You could wash it off but if you have carpets, it will be messy. I should sand back using 80 to 100 grit paper. You can BIN the walls but it will be expensive (and smelly for an hour or so).

 

[ChakaCarm]

Thanks for such a helpful reply. Yes, there are carpets but it's just one wall. So I guess I should attempt to clean the wall and then sand the surface
Costly mistake in terms of time as well as money - but have learnt my lesson!
Any thoughts on what would be best type of paint to use once I've keyed the surface?
Many thanks indeed for your time.

 

[Wayners]

The wilko tough paint won't like going over the contract matt.
Then the contract matt won't like the tough wilko paint.

Contract matt is chalky and dry, also not so smooth, while the wilko paint will be smoother with durable resins in plus seal surface.

 

[ChakaCarm]

Thanks so much for your helpful response.
There are indeed carpets. Having said that, it's just one wall. I guess I'd better wish off as much as possible and then key the surface before painting with something that isn't contract.
Thank you again for your time.