So I have a wall that I had to replaster. Usually, what I do with plaster walls is, because I am never happy with the smoothness of plaster alone, apply blue lightweight drywall joint compound and sand it before painting, that way a plaster wall looks as smooth as drywall.
Now, I know the theory that lime-based plasters (which is exactly what I use) requires up to a month or longer to cure and should not be painted before. What I am not sure is how things change if joint compound is applied: does the plaster need to cure on open air regardless of paint or is it just bad to put paint directly on plaster before it is cured? Because the latter case would not apply if there is a layer of drywall mud between the plaster and paint.
Best Answer
The curing process for lime plaster (Calcium Hydroxide) involves the plaster absorbing and reacting with Carbon Dioxide in the air to form Calcium Carbonate.
Therefore no air impermeable material should be applied to it for the length of the cure, about 3 months. Applying joint compound over it will prevent the curing process, with or without paint.
See: http://www.buildnaturally.com/EDucate/Articles/Lime.htm