Sealing a newly plastered wall for Emulsioning

[chim_knee]

Hello,

We've just had a room plastered and are about to paint straight on it with an emulsion paint.

I have heard conflicting advice regarding using a diluted PVA solution to seal the plaster before painting.

What's the consensus? Is it OK or are there better sealants?

Also, what would the ratio be of PVA to water? 1:1? Des anyone know approximately how long it would take to dry? One coat enough? etc!

Cheers in advance,
Phil.

[pmanson]

Can't you just use a coat of emulsion that is diluted with water?






Waits to be shot down in flames!

>> Edited by pmanson on Wednesday 6th July 14:50

[chim_knee]

That's partly the conflicting advice!

I've read that:

PVA solution is great.
PVA solution shouldn't be used when being painted over by emulsion - not hard wearing enough
Using a base of emulsion isn't hard wearing enough.
etc etc!

[maddog-uk]

I think there is a dulux trade paint designed for jus this job. We re-platered our whole house and basically painted it with a diluted magnolia dulux trade paint. Then for second coat with diluted white so we had a great base. Then we waited and just painted over with normal paint!

[Don]

Go buy a pot of plaster sealer. B&Q. It is specifically for painting on plaster to seal it up ready for painting.

We are having a Conservatory plastered today - this is what we've been told by the plasterer. Oh...and you leave it to dry for a couple of weeks before sealing it too.

[BliarOut]

I thought diluted emulsion was the thing to do. Has SWMBO got you decorating as pennance for Amsterdam?

[chim_knee]

BliarOut said:

Has SWMBO got you decorating as pennance for Amsterdam?

You've met her then?!

No - this is acutally my study so has a bit of a personal incentive for me!

>> Edited by chim_knee on Wednesday 6th July 14:56

[chim_knee]

Don said:

Go buy a pot of plaster sealer. B&Q. It is specifically for painting on plaster to seal it up ready for painting.

I have seen these but the cynic in me suspected that they are merely diluted emulsion or PVA - just with a price premium!

[BliarOut]

chim_knee said:

BliarOut said: Has SWMBO got you decorating as pennance for Amsterdam? You've met her then?! No - this is acutally my study so has a bit of a personal incentive for me! >> Edited by chim_knee on Wednesday 6th July 14:56

I think so...... back in the nineties at a club near Rickmansworth

[chim_knee]

BliarOut said:

I think so...... back in the nineties at a club near Rickmansworth

[minimax]

pmanson said:

Can't you just use a coat of emulsion that is diluted with water? Waits to be shot down in flames! >> Edited by pmanson on Wednesday 6th July 14:50

that's what I do!

can't see how anything else would be that much better?

[Sleep Envy]

Phil, PVA glue mixed 1:4 ratio with water.

Careful it doesn't run when it dries though, as you'll see the runs when you paint the wall.

Also if it drips onto anything like skirtings or floor finishes wipe it off asap as it's a pain in the RVA to get rid of after.

[vetteheadracer]

Watered down emulsion to seal the plaster is what I used on my new walls.
Best to either use white or if you know what colour you are using then use that watered down.

[chim_knee]

Sleep Envy said:

it's a pain in the RVA to get rid of after.

Cheers Ricardo - can't believe I didn't think to bring this up whilst in Amsterdam! If I'd have known you'd know I would've!





Also - thanks everyone... conflicting advice again! but consensus seems to be that either paint or pva diluted is OK. Cheers!

[Mutant Rat]

PVA solution, as described by Sleep Envy, will certainly do the job of sealing the surface of the plaster.

Sealing and painting plaster before it has had a chance to thoroughly dry out is bad practice though, and can lead to future defects.

[chim_knee]

Mutant Rat said:

Sealing and painting plaster before it has had a chance to thoroughly dry out is bad practice though, and can lead to future defects.

Thanks - it was only a skim and it has been about 2 weeks. Small room too. Fingers crossed!

[Sleep Envy]

chim_knee said:

Sleep Envy said: it's a pain in the RVA to get rid of after. Cheers Ricardo - can't believe I didn't think to bring this up whilst in Amsterdam! If I'd have known you'd know I would've! Also - thanks everyone... conflicting advice again! but consensus seems to be that either paint or pva diluted is OK. Cheers!

No problem

If you're painting straight onto the wall it's worth giving it a very light sanding with fine paper before applying the PVA to get a better paint finish.

It's also good practice to apply a mist coat of paint between the PVA and the first full coat of paint.

[muley]

chim_knee said:

Don said: Go buy a pot of plaster sealer. B&Q. It is specifically for painting on plaster to seal it up ready for painting. I have seen these but the cynic in me suspected that they are merely diluted emulsion or PVA - just with a price premium!

They are. You can buy a big off tub of PVA adhesive and dilute 1 part to 4 parts water and Bobs' your uncle!

[Mutant Rat]

chim_knee said:

Mutant Rat said: Sealing and painting plaster before it has had a chance to thoroughly dry out is bad practice though, and can lead to future defects. Thanks - it was only a skim and it has been about 2 weeks. Small room too. Fingers crossed!

Ah, OK - she'll be right, then!

2 weeks ought to be plenty of time for a skim coat to dry out, even in our glorious British summers!

Worst when you've done a full wet plaster+skim, then sealed it, the trapped moisture can cause delamination of the skim coat and other such nasties, but that won't be a problem in your case.

Good luck with the job!

[Incorrigible]

if it's just a skim and you've left it a few weeks a watered down trade emulsion will be fine

On a "float and set" where a bonding coat of plaster has been applied direct to the bricks you can get chemcals (lime for iinstance) leaching through the plaster (as the water in the plaster penetrates into the old mortar) even a 4:1 PVA solution won't stop this. But you can paint over the trade emulsion with gloss and then re-apply emulsion over that coat