Silk paint

Hello, it's quite posible you are trying to emulsion paint over an oil based paint. Best solution is to lightly sand the walls and apply an acrylic based undercoat primer and wait 24 hours before emulsion painting.

Horrible stuff , really poor decision if this went straight onto fresh plaster . My go to has always been scrape loose , key ( sand lightly) and then fill / prep as normal , sugarsoap or wipe clear of any dust , and paint feom there. Acrylic primer coat is always a good option too but making sure the surface is flat,clean and adhesive to the paint is the priority, acrylic primer will only help if the initial prep is done first . And then your choice emulsion on :) Dan GTS

I would pva tge walls to secure any loose flaking paint. This gives you a blank canvas to paint your matt onto. What's more it takes all the backbreaking /dust out of it. 5 Litres if PVA start at £14. Mix with water according to manufacturers guidelines.

Before buying anything expensive, I'd do a quick test first. Wipe a small area with warm water and a cloth. If the surface softens or becomes slightly tacky, it's likely a silk/vinyl emulsion. If nothing happens, it's more likely an oil-based coating. If it's silk/vinyl emulsion and the surface is sound, I'd lightly sand it and use Zinsser Bulls Eye 1-2-3 before applying your matt emulsion. If the surface is powdery or unstable, then Zinsser Gardz is a better choice. If it's oil-based, lightly sand it first and then use Zinsser Bulls Eye 1-2-3 or Zinsser BIN before painting. I'd test a small area first before buying enough for the whole hallway. It could save you both time and money. ;)