Can PVA seal problem walls prior to lining/emulsioning?

[beano2012]

Hello
Have just stripped old wallpaper off, I discovered it had also removed jagged areas of a weird rubbery paint underneath that had been applied to bare plaster without an initial mist coat. Tiny areas of the paint continue to form nibs all over the place. See photos attached.

I cannot get a decent smooth surface for wallpapering. I was hoping I could just slap a coat of PVA (1:4??) over the whole lot ie the bare plaster and the weird paint to seal off the problem, before lining the walls and painting with emulsion paint

Would this work?
If so, would I still need to size it?
Or are there any better solutions?

 

[curlyzoo2002]

Yes it will or you could emulsion but after
It drys your going to want to rub it down to get the flakes off then fill it then rub it down and seal seal again it would be easier to see with paint. And remember lining paper dose not give you nice plastered walls it just smoves the bumps slightly there still there

And yes always size and let the size dry

 

[JohnD]

NONONONONONONONONONO!



never put PVA on any wall that you hope one day to paint.

 

[curlyzoo2002]

He wants to line to paint y would you line it then strip it to paint the bare wall

 

[joe-90]

The rubbery paint is satin. You really want Zinsser Gardz.

 

[beano2012]

@curlyzoo2002: thanks for the advice. Yea I would prefer to emulsion the walls instead of PVAing them

but if i do emulsion, would I need to mistcoat first all the bare paster areas and as you can see it looks like a map of the Norwegian fjiords - so a mammoth task!
Then would I have to emulsion the whole wall including the areas where the weird paint is?

I take your point about the limitations of lining paper. Thinking of using 1400 grade to smooth the bumps. Not perfect but will have to do.

So do I need to size on top of emulsion or PVA before lining??

 

[beano2012]

@ JohnD ... thanks for the tip.

The thing is that I won't ever want to paint directly onto those plaster walls because they are in a pretty awful state. Being retired.I'm time-rich but money poor so cant really afford the ultimate solution of having them replastered

If I PVA the iffy walls to seal them (and then size them as suggested above), then line them with paper, and then emulsion them, will I still run into problems of the sort you warn against re PVA and paint?

 

[beano2012]

@ joe-90 .... thanks, for the recommendation. This stuff sounds amazing but it's not clear from the web whether it will cover non-porous areas like this godawful paint that is half sticking, half-peeling, half-nibbing to the plaster.

Will it cover this as well?

And would I need to size afterwards prior to lining/emulsioning?

 

[JohnD]

sorry I don't know. The problem with PVA and emulsion is that the glue prevents the paint from sinking into, or even touching, the wall; and its moisture content causes bubbles under the paint, as the glue partially dissolves and expands.

I don't know a benefit from putting PVA on a wall that is going to be papered.

 

[dcdec]

As John D has told you never ever use pva in decorating.

Gardz will seal and BIND porous flaky surfaces and creates the perfect surface to paint or paper because it also evens out porousity of the walls you want to paint or paper. PVA does not sink in, it creates a barrier between wall and product and anything applied on top of it sticks to this barrier and not the wall thus creating a very weak bond.

You will still need to prep the surfaces well, fill and rub down the walls prior to applying Gardz because Gardz will also seal your filler which is more porous than the wall. Filler will draw in more paste if not primed or sealed which could give you adhesion problems. LP will only even out minor bumps and surface defects. I would suggest you use a non woven paper as this will not shrink or expand.
The above advice will cost you more than you'd planned but it will be cheaper than doing it twice and provide longevity allowing for far easier and cheaper re-decoration in the future.

 

[beano2012]

"Gardz will seal and BIND porous flaky surfaces"

Hi dcdec and thanks for this useful info....

but can I clarify one key point with you because I know nowt about this zinsser product? Can I use it on top of non-porous material as well as plaster ie this awful paint skin on top of areas of plaster (see pictures above)? What I don't want is the nightmare scenario of painting it only onto the jagged areas of bare plaster!
Do I still size the wall afterwards?
Also is there a trade name for the non-woven LP? And can you put wallpaper onto it (in case wife changes her mind )

 

[dcdec]

Yes you can use it over the painted surface, you do not need to mist coat bare patches as the gardz seals it.

Non woven LP

http://www.decoratingdirect.co.uk/viewprod/m/MAVNWLPT/

I think they sell nw lp in B&Q and yes you can paint or paper over it.

The gard will bind down the flaky 'nibby' paint, but as i said before you've got to do some filling and rubbing down as well

 

[beano2012]

@dcdec

Thanks for the advice... you clearly know your subject! Will give it a go