Just had walls re-plastered and a ceiling skimmed — how long before we can paint, and why does new plaster need a special first coat?

You've heard right, and it's the single most common way a fresh-plaster paint job goes wrong. Two things matter — drying, then the mist coat:

1. Let it dry properly. New plaster and gypsum skim hold a lot of moisture, and paint over damp plaster traps it and peels. It needs to go from dark and patchy to a uniform pale, matte colour all over — no dark damp patches left. In Dubai's heat that's faster than a cold climate, but thicker plaster and enclosed rooms still need real time (days for a thin skim, longer for thick coats or in humidity). Don't trust 'touch-dry' on the surface; the depth is what matters.

2. Then a mist coat — never neat paint straight on. New plaster is very porous and sucks the moisture out of a normal topcoat before it can bond, so it never really sticks. The fix is a mist coat: ordinary matt emulsion thinned with water (roughly 3 parts paint to 1 part water — check the tin), applied as a thin first coat that soaks in and seals the surface. Once that's dry, your normal coats go on and actually grip.

Order of play: plaster dries fully → one (sometimes two) thinned mist coats → two normal topcoats. Skip the drying or the mist coat and you'll be back stripping flaky paint in a few months.

If it's a whole villa, or a timeline where you can't easily judge whether the plaster's truly ready, it's worth having painting services in Dubai handle the prep — getting the drying and the mist coat right is exactly what separates a paint job that lasts from one that peels.