One of the most common questions we get at the end of a job is 'When can we paint?' The answer depends on what's on the walls and on the weather.
Veneer plaster sets within hours, but setting isn't the same as drying. In normal conditions, give it at least a few days with the heat on and some air moving before priming. In a cold, damp basement or during a humid summer stretch, it can take longer. Plaster that's ready to paint is uniformly light in color, with no darker damp patches.
Taped drywall is a little different. Once the final coat of joint compound is dry and sanded, which is usually a day in good conditions, it's ready for primer. The key is the primer itself: joint compound and paper absorb paint differently, and without a good drywall primer you'll see the seams through the finish coat, an effect painters call flashing.
For new plaster, use a primer made for fresh masonry or plaster surfaces. Plaster is alkaline when new, and some ordinary primers don't bond well to it, which can lead to peeling later.
The simplest way to avoid the guesswork is to have the same crew plaster and paint. We know exactly when the walls went up and when they're ready, and we can schedule the paint to start the moment they are.