How to paint newly plastered walls

Create the perfect finish on your newly-plastered walls in just a few simple steps

Anna-Lisa De'Ath

Published: June 27, 2022 at 12:48 pm

There are many occasions where you may need to know how to paint on new plaster. Maybe you’ve had a room re-plastered, or built a new extension on your home with completely fresh walls. Painting a newly plastered wall requires more preparation than painting a normal wall. You can’t start painting new plaster directly and instead, you will need to seal the plaster first.

New plaster gives a lovely smooth finish to walls and ceilings which makes it the perfect surface for painting, but painting directly onto plaster can cause issues that will lead to paint not adhering and flaking off. If the plaster isn’t thoroughly dry the paint will also trap the moisture left in the plaster which can lead to damp issues and cause the paint to crack and peel. So in order to prevent these problems from occurring you will need to apply a mist coat. This is a watered down emulsion that soaks into plaster to create a bond, acting like a primer, to ready the plaster for the top coat.

How long should I wait before painting new plaster?

Before painting new plaster, it needs to dry properly, but it's not a quick-drying material. In ideal conditions, typically the summer months, it can take from two to three days to two or three weeks. If you can, leave it for at least two weeks to make sure it is thoroughly dry. Leave a window open to help ventilation and speed up the drying process.

One way to check if the plaster is dry or not is by looking at the colour. As the plaster dries, you will see lighter colour patches appear – this means those areas are dry. When the plaster surface is all the same lighter colour the plaster is dry. If you apply paint before the plaster is dry this can lead to other problems in the future, so if you want a good long-lasting paint job you need to be patient.

How to paint a newly plastered wall

			
What you need

Emulsion for the mist coat
Water
Dust sheets
Decorator’s tape or masking tape
Topcoat paint
Paintbrush or roller

Step 1

Let the plaster dry

The very first thing you need to do when painting new plaster is to let it completely dry out and make sure all the damp patches have disappeared. Once the plaster is dry it should be light with no dark spots and a consistent colour and appearance throughout.Your plaster will dry quicker with a heater or if you open a window. While the plaster is drying, put down dust sheets and use masking tape to protect any fixtures and fittings – applying a mist coat can get very messy!

Step 2

Mix a mist coat

New plaster is very permeable, which means it will absorb liquid i.e. paint. To prevent this from happening, a mist coat needs to be applied directly to new, fully dry plaster to help seal it ready for the top coat. A mist coat is made of watered-down emulsion paint and acts as a primer. The extra moisture gives the wall something to absorb so your topcoat should stick better to the walls. Alternatively, you can use a ready-mixed water-based primer which saves you the mess of making a mist coat. To make a mist coat, mix three parts emulsion with one part water. You should always check the paint tin for the manufacturer’s instructions as ratios can vary. You don’t have to use the same paint you’ve chosen for the final topcoat, but you should try to use a similar colour for an even finish. The mist coat will be completely mixed together when the water isn’t settling on the surface of the emulsion.

Step 3

Apply the mist coat and let it dry

There are two different methods you can use to apply a mist coat. If you choose to use a roller, you’ll cover the wall much faster, but it will be very messy as rollers can cause paint to splatter everywhere. Alternatively, using a paintbrush will take much longer, but you shouldn’t have as many drips and splashes to deal with.

Whichever method you choose to apply the coat, work in smooth upward motions until you cover the whole wall. The mist coat is very runny, so whenever you see any drips or streaks, paint over them quickly to prevent them from drying and ruining your perfect finish. One coat should be enough, but you can add a second or even third coat, if you wish, to make sure the plaster is really well sealed. Wait 24 hours for your mist coat to dry before you apply additional coats or the topcoat. A simple test to see that the mist coat has worked is to use masking tape. If it comes off the wall clean, you’re ready to go.

Step 4

Apply the topcoat

Once your mist coat has dried you can decorate as usual. There’s no need to sand down the wall as you’ve already done all the prep and your newly plastered walls should have a smooth finish. Using a roller, apply the topcoat in a V motion for even coverage. For the best results, you might need to apply more than one coat. depending on the shade of paint you choose.

Common mistakes

Applying paint to wet plaster can cause adhesion problems. Applying emulsion to wet plaster also means that it may not bond properly and you could find that it peels off your wall.
Painting on dried plaster can cause the paint to dry very quickly, leaving you with irregular brush strokes and an uneven finish. So to prevent this from happening, you need to apply a mist coat.
If your mist coat is mixed too thickly it won’t absorb very well onto the new plaster. This can be the case with some ready-mixed plaster sealers, so if you are buying one rather than mixing emulsion paint and water yourself, try what you’ve bought on a small patch before misting the whole wall. If it’s thinner than single cream consistency and doesn’t sit on the surface it should be fine to go ahead. If it does sit on the surface and seems a little too thick, it’s likely you’ll have to water it down a further 50/50.

Top image by Getty Images

Anna-Lisa De'Ath

Anna-Lisa De’Ath is a freelance magazine editor and journalist specialising in homes & interiors, gardening and crafts. She has worked on Prima, Good Housekeeping, Woman & Home, Woman and Woman’s Own. Most recently she was Editor-in-Chief for Your Home and HomeStyle magazines. Anna-Lisa also runs The Crafty Country Fox craft workshops from her Somerset studio. Follow her on instagram @mycraftycountrylife.