Painting new plaster a day after its gone on.

[peaps]

Use a contract matt with no vinyl content to prime the plaster. Normally a 70% paint 30% water mixture. The fact that the emulsion has no vinyl means that the plaster will be breathable.

Still don't advise on painting this quickly but this will be the best option!

• Gypsum plaster is vulnerable to moisture - it can have a porosity over 50 per cent by volume. It is not suitable for external applications or internal applications where dampness occurs.


The whole idea is to seal the plaster if it's gypsum based, if you apply anything breathable your walls become damp from internal moisture.....
over time if you don't seal the plaster the walls hold a higher moisture content.

Even when you use a plaster primer paint you have to then seal it with emulsion paint.

Lime plaster does need to have a breathable paint on it however.

 

[peaps]

Just to add, if you apply a water based paint to new dry plaster (plaster can take weeks to dry out) it will suck out the water content, the paint will dry, crack and flake because it has no key...

Also, why would you add ,ore water to plaster when it soaks it in?

 

[vibrobullit407]

Don't use PVA on any area that is to be painted or decorated. It is not designed for this and can react with the paint. I always use a non vinyl matt for bare plaster if painting over. If papering you can just use a thinned wall paper paste to seal the walls prior to papering!

 

[vibrobullit407]

Just to add, if you apply a water based paint to new dry plaster (plaster can take weeks to dry out) it will suck out the water content, the paint will dry, crack and flake because it has no key...

Also, why would you add ,ore water to plaster when it soaks it in?

Easier than writing;

http://www.youtube.com/watch?v=VTuaH-6rGRw

 

[peaps]

http://www.painterforum.com/yabbse/index.php?topic=1779.0

 

[vibrobullit407]

Zinsser 123 is a water based primer that is not needed for fresh plastered walls. It is ridiculously expensive when a watered down non vinyl matt will do the same trick!

The watered down non vinyl matt gets absorbed into the plaster easier than non watered down matt, thus meaning that it does the opposite of what you have suggested in regards to cracking and flaking.

You would then apply the finish coats over this in what ever finish that you are after. This is what I do and have done many, many times with no detrimental effects!

Ask the question in the decorating forum and see other peoples opinions om the matter. Could be a learning curve for us both!

 

[dhutch]

Use a contract matt with no vinyl content to prime the plaster. Normally a 70% paint 30% water mixture. The fact that the emulsion has no vinyl means that the plaster will be breathable.

Still don't advise on painting this quickly but this will be the best option!

Sounds like what I was planning.

The skelling section (onto new plasterboard) has already mainly gone dry, the rest is starting to break out into dry patches (when I say dry, i mean pink rather than brown, if not totally dried) so today I have put two fans on it, cracked the window (most i can open with the house unattended) and turned the themostat up to keep the radiator putting heat in.

Mist coat goes on when I get in a five tonight, second coat goes on after tea, 12 before the blokes movng in.

Plasterer had just finished cleaning up when I got in at half five last night, bar leaving me to clean down the walls (which bar a touch up, i dont have time to repaint) he has done a cracking job of it and for £80 for a good price I think.


Daniel

Daniel

 

[peaps]

Investing the time and money into painting can feel like a total loss when an old stain starts to show through or when the new paint starts to peel off. Priming is recommended for new plaster surfaces. The key to priming new plaster before painting is ensuring it is cured.

Role of Primer

Primer basically acts a safety net for painting. Applying a primer before painting any surface helps to ensure the final coats do not soak through to the surface below and thereby leave an uneven finish. Primer also provides a grip for the finishing coat because paint does not bind to every possible surface.

Plaster

Some plastering materials contain a chemical compound called “alkali.” This compound remains “hot” for up to three months, which is why an oil-based paint cannot be used over newly applied plaster. The alkali in new plaster will attack the oil-based paint. Applying an alkali-resistant primer can shorten the wait to apply an oil-based paint over new plaster. Other plasters are alkali-free, but use of an alkyd primer is still recommended.

Curing Plaster

Primer should only be applied to new plaster once it has completely dried, which can take several weeks. The process of drying is called “curing.” New plaster can be tested for curing by dragging a finger across, and if there is a squeak, there is still moisture in the plaster and it is not ready for priming.

Wet Plaster Warning

Applying primer to plaster that is not allowed to completely dry will result in an unsealed surface. The surface might be entirely unsealed, or partially unsealed. Either way, unpleasant results are likely, at best an uneven finish and at worst, bond loss and de-lamination (paint flaking). Similar results will occur if a polyvinyl acetate (PVA) based primer is used over lime gauging or lime-containing plasters.

http://contractpainters.co.uk/blog/?p=183

 

[dhutch]

All of thats great only, i AM painting the plaster tonight, becuase the new tenant IS moving in on Saturday.

My intended finish is a brand name non sythetic non oil based matt white, dulux/crown/whatever which I already have.

As I see it my options are
- Slap on a 50/50 or 70/30 etc diluited mix at about 5 and then a top coat and about 7-8ish
- Buy a tin of primer enroute home (limited to whats in stock in BnQ and slap that on at 5.30, top coat on at 7-8ish.

Currently im leaning towards just slapping a watered down coat on becuase.
- I have it, so dont ahve to detour to BnQ, increasing the time between coats.
- I know how it will behave and I know it will bond to the top coat which will be the same.
- I know that is is waterbased, covers fairly well, and fairly breathable.
- Its a ceiling and it will either be fine, or ok, even if its really badly adheared.
- Regardless of the outcome, having got back from work at five, I must leave the house with a painted ceiling before 10.


Daniel

 

[dhutch]

Thanks to all for the comments so far by the way, including yourself peaps, even if it feels a bit like im going ahead anyway, which im only doing becuase I have no other option.


Daniel

 

[peaps]

Thanks to all for the comments so far by the way, including yourself peaps, even if it feels a bit like im going ahead anyway, which im only doing becuase I have no other option.


Daniel

You are between a rock and a hard place because of the time restrictions.

It's not a personal thing, I just give a balance view.

 

[vibrobullit407]

I have to admit that this is not a good idea especially that the matt will not dry very fast if the moisture is in the plaster.

Do not buy a specific plaster primer as it is not needed., Watered down non vinyl matt (mist coat) will suffice.

The problem is that you are painting over damp plaster. There is no specific paint to my knowledge that will allow this in there application instructions but I don't know everything.

Just to clarify that the mist coat is a primer coat. It is watered down so that it can penetrate the surface of the plaster which helps bond to it. It then allows you to paint over the top with the preferred paint system.

 

[huddsspread]

My bathroom had to be renewed, and when you have a moaning wife and four kids it had to be quick. So in 3 days it had been ripped out, re modeled, re built, re plaster and re fitted.

So it was ok for a day or two, while the plaster was drying, then she starts moaning again, so as the plaster was pink again, i got some cheap b n q white paint which is 1% paint and 99 % water and slapped it over...then being the master decorator i am, i decided not to use bathroom paint, and used normal emulsion.

two months later the red paint is/has started flaking off everywhere. There is a few things it could be, didnt use bathroom paint, bathroom get moisture in the air, or didnt let the plaster fully dry.

BUT the cheap mis coat of white paint underneath is perfect?? Got a solution though, by tiling over it!!!

So i will now on ALWAYS use a primer, and use kitchen/bathroom paint.

Think shes on about the kitchen next....brilliant.....think i might get a painter in, as i hate painting!

 

[peaps]

I have to admit that this is not a good idea especially that the matt will not dry very fast if the moisture is in the plaster.

Do not buy a specific plaster primer as it is not needed., Watered down non vinyl matt (mist coat) will suffice.

The problem is that you are painting over damp plaster. There is no specific paint to my knowledge that will allow this in there application instructions but I don't know everything.

Just to clarify that the mist coat is a primer coat. It is watered down so that it can penetrate the surface of the plaster which helps bond to it. It then allows you to paint over the top with the preferred paint system.

Plaster primers will allow it to breath and dry out before the final top coat, the primer I use is white......

Will allow him to get atleast a colour on and he can give it a lick of paint when it has had chance to dry out, then the paint will seal the wall so moisture won't get in. Plaster drink a huge amount of water, at times you can smell it in the wall if left in a high moisture enviroment.

 

[vibrobullit407]

The b&q cheapo will have had no vinyl in it which will help the plaster breath. When you applied a vinyl emulsion over the top the moisture won't have been able to escape and made the paint system flake off.