Identify the surface and follow the current instructions for your exact products. Do not sand or strip uncertain old coatings. Read the safety guide before disturbing materials.
Dry enough is not a calendar date
New plaster needs to dry sufficiently for the chosen coating. Thickness, the background, ventilation and temperature all affect that process. A pale surface can be useful information but is not proof that everything underneath is dry.
Do not force rapid drying with fierce local heat. Follow the plasterer’s and coating manufacturer’s advice, and resolve leaks or persistent moisture first. New gypsum plaster and traditional lime plaster are not interchangeable substrates.
A mist coat is a specified first coat
Some paints call for a diluted first coat to manage suction on porous plaster. Others specify a dedicated primer or a particular system for new plaster. The correct dilution belongs to that product, not to a universal internet recipe.
Use the paint maker’s written instructions for the substrate and exact product. Do not add PVA as a general painting sealer. It can leave an unsuitable film beneath the decorative coating.
Use the first coat to inspect
The first coat often reveals small defects that were hard to see on bare plaster. Let it dry before deciding what needs attention.
- Confirm the plaster and conditions meet the coating specification.
- Remove suitable surface dust without soaking the wall.
- Apply the specified primer or first coat, using only the permitted dilution.
- Allow it to dry and inspect for defects or loose areas.
- Make compatible minor repairs, prepare them and prime as required.
- Apply the finishing coats at the stated spread rate and intervals.
Common mistakes
- Copying a dilution ratio from a different brand or product.
- Painting a dark, damp patch to make the wall look uniform.
- Using a thick topcoat to bridge dusty or loose plaster.
Ask the plasterer or a suitable specialist about unstable plaster, ongoing damp, salts or uncertainty over gypsum versus lime.
Sources & further reading
Original general guidance from Aethos, informed by the resources below. These references cover relevant safety, materials or techniques, not a specification for your property. Product examples are not paid recommendations.
- Farrow & Ball: paint finishes (opens in a new tab)
Different products and sheen levels for different surfaces. Check the current product advice sheet.
- SPAB: limewash (opens in a new tab)
Traditional finishes, suitable substrates and caring for older buildings.