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How long should plaster be left to dry before it is painted?

(20 Posts)
FishfingersAreOK Thu 11-Oct-12 18:40:45

Whole house being re-done. Some bits being skimmed over new plasterboard. Some bits being re done down to patches of brickwork. All be re-wired too.

So how long until/how do I know if dry enough to paint?

What will happen if it is painted when it is not dry enough?

Please help/experiences please.

PigletJohn Thu 11-Oct-12 19:10:42

the new skims will be days. The brickwork will be weeks. Fresh air, ventilation and draughts dry it faster than heating. The windows will fog up while it dries.

You will know it is ready when all the shiny chocolate-brown has gone and it is all matt pale pink. Clean off all residual dust and give it a couple of coats of Dulux Trade Supermatt, which is a non-vinyl emulsion, and allows the residual moisture to evaporate through its porous surface. It is most economical to use the white one. It is not very hardwearing or washable. Once you have painted it white, any remaining blemishes will become obvious to the eye and you can fill or smooth them. Repaint those patches afterwards.

The first coat of emulsion on bare plaster should be thinned with water so it soaks in. You will find it disappears into the plaster, which is correct. Do it again and the second coat will lie on the surface more.

Resist the temptation to treat it with a vinyl silk or any more costly paint or wallpaper for at least another month.

Never never never never put PVA glue on any surface that you hope one day to paint. There a still a few plasterers who recommend it, but most of them have been murdered by angry decorators.

SeveredEdMcDunnough Thu 11-Oct-12 19:13:22

PigletJohn, I think I love you.

(was lurking for the answer!)

JammySplodger Thu 11-Oct-12 19:20:49

Um, can I sneak in with a quick question too please? I'm repainting our bathroom, and some fool (before we lived here) painted fresh paint directly onto plaster, and it's now starting to flake off in patches.

Am I alright just sanding down the flaky patches and painting over the top or do I need to do something a bit more involved?

PigletJohn Thu 11-Oct-12 19:40:00

use a broad metal scraper, not sandpaper. It will be less dusty.

If it won't come off easily, leave it on. you are only trying to remove the loose stuff.

use fine filler with a broad metal filling knife to smooth it. Again use a scraper not sandpaper if you have put too much on, preferably before it sets hard. A filling knife is far more spriny and flexible than a scraper. Thow it away if the blade gets nicked.

Applying too much filler is wasteful of filler and especially time and effort, because after you have put it on, you have got to take it off again.

flaking paint might also indicate condensation. I hope you have got, and use, a bathroom extractor fan.

golemmings Thu 11-Oct-12 19:42:44

Ok, so how long before we can hang a boiler on new plaster? Can't wait to have heating back but the wall the new boiler is going on isn't built yet...?

PigletJohn Thu 11-Oct-12 19:47:30

doesn't matter.

The fixing bolts will go through the plaster into the brickwork. Nothing is ever fixed to plaster, except perhaps posters of lady tennis players.

If it was me I would prefer to paint the wall first to avoid seeing bits of bare wall behind the boiler and pipes.

smalltown Thu 11-Oct-12 20:30:34

Message withdrawn at poster's request.

PigletJohn Thu 11-Oct-12 21:20:04

I expect so. Ceilings dry fast. You will be able to see when they're dry. Use at least a soft brush to remove any dust. A soft broom will do.

FishfingersAreOK Thu 11-Oct-12 22:45:59

Thank you - so there are still the odd patches of dark - this is probably where the thicker bits are. Decorator not due for about 10 days so downstairs may well be OK but upstairs may have to wait. Thank you!

JammySplodger Fri 12-Oct-12 11:19:54

Thank you!

LittenTree Fri 12-Oct-12 11:33:42

Another Q!:

You recommend dulux trade supermatt, PigletJohn - is that to be used as an undercoat so you can put the colour of your choice on top of the maybe 2 coast you apply?

PigletJohn Fri 12-Oct-12 11:55:13

it is particularly recommended for bare new plaster, because it is a non-vinyl emulsion paint, so the new plaster can continue to dry out through its porous surface.

it is not very durable or washable, so you will most likely want to redecorate over it after a month or so. The PBW is always cheaper than colours, so it makes sense to use PBW as your initial treatment, in the knowledge that sooner or later you will be overpainting it.

As it primes the wall and evens the colour and absorbency, you will not need so much of your final colour to avoid patchiness as if you were painting onto bare plaster or a patched wall, and it will be easier and quicker to apply.

The initial white coat will also highlight to the eye any remaining blemishes in the surface so you can correct and repaint them before you use your more expensive finish coat.

LittenTree Fri 12-Oct-12 12:04:11

Thanks, I get it now!

crusoe16 Fri 30-Sep-16 07:05:07

We're plastering today. I want the walls painting with Farrow and Ball mid-November but our decorators are insisting they can only use Dulux Trade because it's breathable....Is that right? Hoping Piglet John is still around....!

PigletJohn Fri 30-Sep-16 08:55:14

Yes, until you know for a fact that it has fully dried.

BumbleNova Fri 30-Sep-16 09:41:03

do you have an old house crusoe? farrow and ball has plastic in it which means it stops the walls breathing as old houses are designed to do. the result of which is damp. have you looked at edward bulmer or little greene? great colours and no plastic.

crusoe16 Fri 30-Sep-16 11:16:36

Will look those up BumbleNova - thank you. Yep, old listed house!

Need to match F&B Railings.....

Thank you PigletJohn too.

PigletJohn Fri 30-Sep-16 13:17:02

you can have Supermatt tinted to colours of your choice, but it is more expensive than off-the-shelf white or magnolia.

If it is part of a professional job where you are paying plasterers and decorators, the cost of the paint may not be significant, though.

It's easier to call in to your local decorator centre, I think, than to order online. They will have the rack of colour samples.

divs59 Sun 16-Oct-16 18:42:08

Hi PigletJohn, if you are still watching this thread. We have had our house skimmed, i can see it is starting to dry but still not there. It will take another week for them to dry, my builder told us to sand the walls and cieling with sand paper before we can paint. Could you suggest if this is the only way to sand the walls and ceiling as it will take long time to cover the full house.

Also if we use supermatt, will 2 weeks be enough to wait before we paint the final colours ? given the fact weather is now getting cold. Could we use heaters in the room to dry them and then can paint in 2 weeks. Please advise.

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