How to prep this surface for matt emulsion?

[SJRSJR]

Hello, Hope you can advise me here.

Having started flicking a bit of loose paint off a plastered wall, I ended up peeling the lot off,

The paint came off one wall in its entirety and is down to the bare plaster. It’s just the one colour and I assume when it was first done they hadn’t done a mist coat first.

The other wall was more difficult - it came off but it still retains some colour. Could it be that there’s a coat of PVA over it? I dabbed some thinned down matt emulsion but it didn’t really connect, it didn’t feel like there was any absorption.

How would I go about prepping it for emulsion paint? Thanks

 

[Wayners]

Gardz and paint is a safe bet. Do not mist coat the gardz with cheap contract matt!
Don't use cheap contract matt for anything.

If you buy a quality emulsion you can read the application data sheet online that will tell you how to use paint if painting over a dry surface. Sometimes it says use the appropriate primer which isn't helpful, or it will say thin emulsion 10% for first coat.
I spray acrylic primer undercoat on plaster as a primer as it's flawless vs a roller thats not flawless so I recommend gardz. It's easy to apply and seals surface really well.

Then straight on with a quality emulsion allowing 4 to 6 hours between coats. Will take 3 coats to cover.

 

[SJRSJR]

Thanks Wayners. Yes, the data sheet says all that - prepare by priming bare surfaces with their primer or sanding down gloss surfaces. Then seal with a 5/10% first coat.

It'll be Johnstone's Perfect Matt. So you say put on a coat of Gardz then 3 coats of the undiluted Perfect Matt? Should I also do the same on the wall that I got back to the bare plaster?