New plaster - how long to dry before mist coat

18 Feb 2015
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United Kingdom
Currently having a new bathroom installed. Walls and ceiling have just been plastered (yesterday), how long does the plaster need to dry before I can start the mist coat?

I need to move fairly quickly as I'd like to get the painting finished in areas we will no longer have access to at the end of the week when the installers have finished (behind the towel radiator and a wall to the side of a very snug fitting vanity unit).

The installers seem to think I can mist coat as early as Tuesday evening, will the plaster really be dry enough by then? The radiator I could possibly remove at a later date to paint behind but the vanity unit will be sealed in and tiled round so non-removable.

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Leave the rad in, crank up the heating, open a window.

Depends on the depth of plaster, and what surface the plaster went on (board, render etc). Good chance it will be dry enough for paint mid week.
The ceiling has been plastered over board, the walls have been skimmed over the old wall (plus a few patches of render where the pipe works gone in).

Rad has not been hung again yet, so not functional ... I was hoping to paint the wall behind it before it gets hung.
Leave the rad in, crank up the heating, open a window.
No, no! Grins. Every single plasterer has told me not to do this - if the plaster is forced to dry too quick by the use of radiators or dehumidifiers, this can make the plaster crack. Opening the window is a great tho!

If it's just a plaster skim (no hardwall etc) then it's ok to mist coat after about 3 days, providing the plaster has changed colour all over, a light blush. If not, give it another day or two.
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Okay great - next question(s)...

Diluted Contract paint for the mist coat on fresh plaster I presume? But we have one wall that has not been re-plastered or skimmed (the installers just felt it wasn't necessary)...

Current paint is a nasty yellow/green colour, and we want a nice bright white for the new bathroom. What do I use for under coats on a pre-painted wall and how should I prepare it (light sand perhaps)?

And what rollers to use for new and old walls - foam or a long haired type?

And what's the best type of paint to use for the top coat in a bathroom, we'd like to get as close to a matt White as possible.

Foam or short hair rollers are fine. I use the basic short hair rollers with my painting and foam for gloss work on doors etc.
The yellow/green colour just may need an extra coat of paint, but no prep if it's sound and clean.
Diluted contract paint is spot on, just what you need for bare plaster.
And last, if you want a matt finish, make sure you don't buy the fashionable flat matts that are the rage at the mo, and one that is suitable for bathrooms or washable. Reason why is flat matt paints mark very very easily and water/steam will probably create streaks and marks in time! (I learned the hard way :) )
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