Let new plaster dry and follow the first-coat instructions for the paint system you choose. A mist coat or specified primer may be required. There is no universal dilution ratio or fixed drying time that is suitable for every product and room.
Start with the product instructions, not a universal recipe
Online discussions often give different ratios, coat counts and sanding advice. The Reddit question linked below shows why a recipe can sound convincing while still conflicting with another answer. Use those discussions to identify the questions, then check the selected manufacturer’s instructions.
Keep the plaster and paint details together. If someone recommends a first-coat treatment, ask which exact product it applies to and why it suits the surface. Avoid mixing advice from different systems into an improvised specification.
Do not plan the finish around an assumed dry date
Tell the decorator when the plaster was applied and about the conditions in the room. A calendar date by itself is not a complete assessment. Ask how readiness will be checked and leave flexibility in the schedule if the background is not ready.
If only part of a wall has been repaired, make that visible in the brief. The new area and the existing finish may need different treatment before the room is painted as one surface.
Look at the surface before hiding it
Record obvious marks, uneven areas or defects and discuss who is responsible for putting them right. Ask what the decorating preparation includes and what needs to go back to the plasterer. That conversation is easier before the final finish has been applied.
Do not add extra steps solely because an online checklist includes them. Agree the preparation for the actual surface and chosen products. The purpose is a suitable background and finish, not the highest number of operations.
Ask these questions before booking
Which first-coat treatment will be used? Who will resolve surface defects? What happens if the plaster is not ready on the planned start date? Which products will be recorded at handover?
For your enquiry, include wide photos and close-ups of areas you are worried about. We can discuss the decorating scope, while a final specification needs the actual condition and product choices.
Questions homeowners ask
What is the right mist-coat dilution ratio?
Use the selected paint manufacturer’s instructions for that product and surface. Do not treat a ratio from an online discussion as universal.
Should every newly plastered wall be sanded all over?
The required preparation depends on the actual finish and product system. Ask for the surface to be assessed and for necessary defect correction to be agreed; extra sanding is not automatically the objective.
What if the first coat is patchy or peeling?
Do not assume another coat will solve it. Record the product, preparation and affected areas, then ask for the cause to be assessed before more paint is added.
Sources & further reading
Technical decisions should follow the actual product instructions. These references support the planning points above.
- Dulux: painting new plasterManufacturer guidance on drying and the first coat.