Plaster sealer or just a mist coat?

louisdog

Hi all

My new study has just been skimmed today so I need to paint it quite soon, Sunday or Monday probably.

I have bought some matt emulsion and also some plaster sealer; been googling around and am feeling most confused about which to use, can anyone help please?

Are there any disadvantages to plaster sealer apart from it being expensive? Seems like slapping that on will save time compared with a mist coat.

Be grateful for any advice for and against either one

Oh also, if using a mist coat for the coloured walls, should I use watered-down white or coloured emulsion? The white is cheaper but not sure which is best...

Thanks!

Cheers
Alex

nickj_2

just get a tin of preferably non vynyl matt emu although if that's what you've got it's no problem - you can use white all round , don't bother with sealer
you need to thin paint down so it soaks in to the wall ,

louisdog

Thanks Nickj, good to know I can use white for the mist coat. The emulsion I have is non-vinyl.

So is the plaster sealant bad in some way, or just un-necessary as the mist coat is adequate?

I don't understand the difference between the two methods I guess.

And then I keep reading that I should be using PVA instead :eek:

Cheers
Alex

misgrace

Louisdog, Plaster sealer is another way for them to make money from you, ( as if the companies dont make enough) :eek:
The professional decs use watered down matt emulsion as a mistcoat on new plastererd walls, thin the mistcoat down by 25-30%, and apply to your walls, this will get right into the plaster, and not sit on top of it like PVA.
This will seal the walls, and help them to breath, the PVA will not allow the plaster to breathe, it just sits on the walls, like a film, therefore when you paint your first coat of emulsion on top of the PVA, it will not penetrate into the plaster, but sit on top of the PVA.
There is posts on here where people have had so much grief, paint coming off in strips, bubbling, cracking etc.

Do it like we said, after you have applied your mistcoat, then apply your first proper coat, and even thin that down by approx 10%, and even your subsequent coats.

Never apply PVA on new plastered walls :eek: no matter what anyone tells you.:)

louisdog

Thanks for your help!

Should I really thin all coats by 10%? Is that just for new plaster not regular redecorating? Just trying to understand it all.

Cheers
Alex

latecomer

The thinning down is because the fresh plaster will draw lots of moisture out of the paint and can cause it to crack. The extra water helps prevent this - we've in the middle of doing our extension and loft conversion and using 10L tubs of Crown white emulsion that B&Q have on offer at the moment. It even specifies how much to water down for mist coats.

louisdog

Ahh, thanks.

I didn't see any Crown on offer and bought B&Q own, d'oh. But will definitely water it down.

Cheers
Alex

Astec

Yeah the 10l crown tubs are great. Water down for mist cost, 2 parts paint 1 part water roughly, and thin just a little 10% water on other coats to help it go on. I ha3 3l of PVA left after my skimming was done and still didn't use it.

I'm going for a light colour so doing 2 coats white (inc mist coat) and 1 coat colour. The white is so cheap it's better to use that then the colour which is 10 times the price. For a darker colour you will probably need 2 or more coats of colour.

B&Q are good with returns, so if you've not opened the tins swap it for the crown stuff.

LandyAndy

We had our bathroom ceiling replastered three years ago. I just gave it two mist coats of white matt (a 50:50 and a 75:25) and then two ordinary coats. Still looks as good as new.

Lopsie

I don't know how much the 10l tub was in B&Q but i got a 10l tub for £12 in Huws Gray yesterday for new plaster work, which i thought was a pretty good price.

gingerninja72

Just to add to this, our kitchen is current an empty shell and ripped back to brick. We are having the ceiling overboarded and then skimmed and the walls plastered

Is this mist coat method recommended for the ceiling also? If emulsion is thinned down 50/50, wouldn't it be really difficult to apply to a ceiling? Wouldn't it drip like mad? Advice appreciated!