Mist coat on new plaster ?

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The plaster in my new build extension is now a week old, all dried out on the surface.
> Is it ready for the mist coat?
I want to get this right, both the paint and method.
The plaster is very shiny and I have heard that can be a problem applying paint to?
> Shall I wash it, lightly sand/key it, and then apply the mist coat?
> What paint for a mist coat in white? I plan on using Crown matt, would that be ok?
> Or should I use a non-vinyl matt for the mistcoat? Problem is most matts don't say if they are vinyl or not. Does it matter? I would think so because new plaster still has moisture in it and vinyls don't breathe, or do they?
> How much dilution for the mistcoat? I find that it depends on the brand. Dulux Trade matt is very thick and needs lots of thinning?? Others need much less water
> Roller - I will use a Hamilton medium pile roller, is this Ok for a mist coat?

Thanks
 
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If it was skim onto boards then it's almost certainly all dried out, if it's deeper areas onto backing plaster then it may not be. Colour needs to be consistently light pink throughout.
Mist coat 50 50 Matt white emulsion and water
Light rub down first with fine sandpaper is best but often not done
That's just my 2pence worth as a plasterer, I'm sure you'll get more advice from the decorators on here.
 
Many thanks 23vc.
Plaster
It is a mix of skimmed board and skimmed browning, Thistle base coat, very thick in one area, which I assume will take a while to dry out down to the base wall.
But it is all a very pale pink and I hope would take a mist coat in the coming week?

>> Comments from Decorators please ........
Preparation

> So do you think I should wash and lightly sand the new plaster? There is a shine and sealed feel to it which doesn't at the moment look very absorbent?

Mist Coat ?

Good to hear that you say a 50/50 mist coat because I often end up thinning good top coats such at Dulux Trade Matt by 10%+ anyway just to make them workable, so a mist coat is going to need much more water.
> What paint, not just brand but type? Obviously a matt but I assume it should be a a pure matt, a non-vinyl matt? And how do I know which is which? The vinyls sometimes have vinyl written on them but I haven't seen any that state they are NOT vinyl.
> I understand there are specific New Plaster paints. Are they without vinyl?
But a lot of people use ordinary paint, which type? I hear of cheaper but quality paints - Leyland, Albany. Are they breathable non-vinyls?
 
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Don't rub down on raw plaster. Get the mist coat on first. This will high light ant imperfections that can be filled or rubbed down. Follow on with full coats afterwards. A "contract" matt is best for first coats as there is no vinyl in it. Most paint don't actually say " Vinyl" on thin any more.
 
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Thanks Robbie,
I understand to not break the sealed burnished surface, but it feels very shiny, almost glazed, possibly overworked, I don't know!?
> Could I wipe/wash it or just proceed with a mist coat with no prep then dress everything from there?
> Contract Matt sounds fine, 50/50 thinning or less??
> Do I put just the one thin coat on initially?
> Or do I put a few on to create a colour blocking? Then dress/prep/fill/sand it?
 
Sanding new plaster can scratch the surface that can be seen when its painted. If the surface is nice and shiny then the plasterer has polished it too much, they tend not to care about the painters that follow. One mist coat is all that is required then move onto full coats. Sometimes the emulsion can skid all over the place when the surface has been polished. A coat of sealer could be used instead, Zinsser or similar. I would put first coat on but don't thin it too much. Leave it to dry properly as if you try and get further coats on too soon it can activate the first coat and not cover
 
Thanks Robbie
And the mist coat, 20-30% thinned on the contract emulsion?
Or am I looking for a certain consistency, single whipped cream or similar?
 
I'm a DIYer and use Dulux supermatt 3 parts paint to 1 part water for misting as per the instructions. It needs to be non-vinyl so if there's any drying still going on the moisture can escape.
 
I never worry about mixing it to a certain specification, pint or water in a 10 litre bucket and a good stir. Doesn't need to be too thin or it will be everywhere.
 

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