How long does plastering take to dry before you can paint?

The general rule is to allow fresh plaster to dry for at least two to four weeks before painting. A standard skim coat of finish plaster (about 2mm thick) applied over existing plasterboard typically dries within two weeks in a well-ventilated room during warmer months. In winter, or in rooms with poor airflow like bathrooms and basements, it can take four weeks or longer. The plaster should turn from dark pink to a uniform pale colour across the entire surface before you touch it with paint.

Do not use a heater or dehumidifier to speed up drying — this causes the plaster to dry unevenly, leading to cracks and a weak surface. Natural ventilation is best. Open windows during the day and close them at night. If there are any dark patches remaining on the wall, the plaster is still wet in those areas. Once the wall is uniformly light and dry to the touch, apply a mist coat first — a diluted emulsion (roughly 70 percent paint to 30 percent clean water). This seals the plaster and gives the topcoat something to grip.

Thicker plaster applications take significantly longer. If walls have been re-rendered with a scratch coat and finish coat — common when replastering old brick walls — expect six weeks or more of drying time. Board-finished walls (plasterboard with a skim coat) dry the quickest because the board absorbs moisture and the skim layer is thin. If you are on a tight schedule, discuss plasterboard dry-lining with your plasterer as an alternative to wet plastering on solid walls. It is faster to apply and faster to dry.