Painting over an unidentified layer

[LabudMoj]

While removing wallpapers in a house built circa 1970, underneath it I have found a layer of what seems to be some kind of glossy paint, that flakes off at some places but in most is stuck firmly on the plaster. I have sanded where it flaked off and applied two coats of matt paint. Now before moving onto to the next coat I decided to stop and think as I noticed that the newly applied matt paint is showing tiny cracks at several locations - probably the glossy layer is not porous enough to take any paint?

Anyway, I have been advised by a builder that I should just buy PVA and mix it with some paint and do a couple of coats more, but I am not sure that is such a great idea. Is there any way I can correct this, without having to remove everything down to the level of plaster?

 

[Robbie uk]

Typical builders ...dont know what theey are talking about when it comes to painting !!! DO NOT PUT PVA ANYWHERE NEAR THE SURFACE TO BE PAINTED OR IN THE PAINT!!!

If the surface was a gloss type finish then that is why the emulsion is cracking. Give the surface a good rub down with some medium grit paper and apply a thinned coat of oil based undercoat. When dry this will allow further coats of any type of emulsion to be applied on top.

 

[misterhelpful]

Typical builders ...dont know what theey are talking about when it comes to painting !!! DO NOT PUT PVA ANYWHERE NEAR THE SURFACE TO BE PAINTED OR IN THE PAINT!!!

If the surface was a gloss type finish then that is why the emulsion is cracking. Give the surface a good rub down with some medium grit paper and apply a thinned coat of oil based undercoat. When dry this will allow further coats of any type of emulsion to be applied on top.

Spot on!!

 

[LabudMoj]

Thanks Robbie uk! I think I'll follow your advice.

I just wonder whether a wickes generic solvent based undercoat, thinned down to a 25% white spirit mix would do? Sorry if I am asking the obvious, but I really have zero experience.

 

[malshep]

Wickes' paints are diabolical.
Leyland Trade 2.5L £12 from Screwfix is cheaper and much better.
Pour enough to do the job out of the tin into clean jar, tin etc and add thinners, stirring after each small addition, until sufficiently liquid on the day.
Probably 5%-10% not 25%