To use PVA in paint or not? That is the question.

[martyn1967]

I recently renovated a 3 bed house, all plaster off and back to bare brick, dot n dabbed allwalls n skimmed them.
Then I mixed a 3 to 1 pva and sealed all down stairs Walls and then gave them 2 coats of magnolia (not watered down), it looked great.
Then about 2 days later to my horror it started to get the orange peel effect all around the ceiling lines and was in my eyes a disaster, luckily for me it was my property and the new awaiting tennants weren't bothered as they papered it.
Any plastering I've done since then I have not used anything other than undiluted paint and never had any problems since, so my advice is Steer clear of the dreaded PVA....

[wrinx]

Sure I remember TV DIY shows recommending PVA many years ago... I could never understand why but perhaps that's where it all started

wrinx

[upagumtree]

Just mugged up on the Crown website and some interesting info.

1. They are happy for vinyl matt to be used as a mist coat when watered down up to 40% (I always thought that was a no no)

2. There is obviously a vinyl in vinyl matt and they class it as a Vinyl Acetate Copolymer which is really close to Poly Vinyl Acetate (or is it )


http://www.crowntrade.co.uk/Product%20D ... tVinyl.pdf

[Have Brush Will Travel]

Just mugged up on the Crown website and some interesting info.

1. They are happy for vinyl matt to be used as a mist coat when watered down up to 40% (I always thought that was a no no)

2. There is obviously a vinyl in vinyl matt and they class it as a Vinyl Acetate Copolymer which is really close to Poly Vinyl Acetate (or is it )


http://www.crowntrade.co.uk/Product%20D ... tVinyl.pdf

1....No harm at all using Vinyl Matt for a mist is its over a skim...and by watering it down by 40% you more or less break down the binder in the paint anyway which would make it permeable...although its an expensive mist coat and probably wont cover very well...

2...Not sure about this one, but a copolymer is a combination of two or more others...and I think this is just a play on words from the paint companies...like when window firms tried to change UPVC to the more arty and techy sound PVCu...so I think they are the same things.

[royaloakcarpentry]

Apparently, as I have done a bit of research about this issue...............There are cans of emulsion lurking on the shelves at a well known DIY store, which I can't name for obvious reasons, however the B&Q branded emulsion they sell has in its instructions to PVA before painting!!

You are all wrong anyway, you can indeed seal plaster with PVA and emulsion over it. It is only the re-decoration when the paint will peel off with the roller lol.

[Adz76]

I've never added it to paint and I never would. If I need to seal old or new walls I'd use a stabalizer or a mist coat. Plus how many paint manufacturers include the phrase, " can be added to PVA " on the back or front of the can? I see why some would assume this can be done, but there's better ways of achieveing a better result. Saw two guys adding it to masonry paint as a one coat seal and 1st coat. You could see the spur marks all the way up the drive way to the house.

[Have Brush Will Travel]

Soz to inform you but iam married to a plasterer and he does not recommend using pva on fresh plaster and doesn't no of any plasterer who would suggest that

so the idea came from some other trade who probably doesn't like decorators

mandy

That doesnt narrow it down much to be fair...

[grumbles99]

I'm a little confused. The accepted advice is not to use pva but a paint such as Dulux Supermatt already contains pva as listed on the datasheet?

Composition (nominal)
Pigment: Lightfast Non-Lead Pigments.
Binder: PVA Copolymer Emulsion.
Solvent: Water.

edit Super Leytex also refers to the pva co-polymer resin.

Or is it the pva dilution level that causes the re-action problem?

[deem]

Slightly off the question but I've used Dulux plaster sealer under matt emulsion in a sometimes damp conservatory (in autumn/winter) and it has been great. Never had any problems with peeling, flaking. Just absolutely solid finish. I don't know if it is PVA based or not but it works in my experience.

[SteveOC]

The brick course wall in my conservatory was plasterboarded (dot&dab) and skimmed by the installers.
They left me a canister of PVA and told me to leave the plaster to dry out, and then mix the PVA 50:50 with water and paint it on the walls to seal the plaster which I did some weeks later when the plaster was very pale pink coloured and no sign of moisture remained.
I am pretty sure that they used the same stuff on the concrete base now I think about it.

On that basis, I assumed that new plaster needed to be sealed with PVA if the plasterers said so - I must go look at the canister as I still have it.

Thinking about it though, provided that the plaster has dried out - is it not a good thing if it is sealed to prevent moisture entering in the future - or would you need to 'tank' the brickwork before plasterboarding to prevent ingress from outside?

Steve O.

[wine~o]

Steve O, don't know if you followed all of this thread, but Pva over plaster is a NO-NO..

Plasterers (some) advice it incorrectly,

Painters and decorators never do.

Moral ?

Plasterers should stick to Plastering...

[MadRay]

Had to emulsion (Diamond Eggshell) a kitchen this week....plasterer had patched walls and used pva to coat up all the walls.
It was a nightmare....emulsion just slides off and took ages to dry.

PVA + EMULSION = MESS

[SteveOC]

Steve O, don't know if you followed all of this thread, but Pva over plaster is a NO-NO..

Plasterers (some) advice it incorrectly,

Painters and decorators never do.

Moral ?

Plasterers should stick to Plastering...

Yes I did read the whole thread thanks - just saying that I was told to do so by a plasterer and not a painter/decorator and assumed that the advice was kosher as I had never done any plastering.
I don't think that it could have had any detrimental effect on the emulsion (I used a Crown matt paint called Old English White IIRC). Still - live&learn.
Just curious as to whether there are circumstances where you would want to seal the plaster (assuming it has dried out).

Steve O.