Contract matt is a cheaper version of vinyl emulsion paints as they contain less polymer binders in their formulation. This makes them cheaper than other interior paints, meaning they are used by landlords and builders in newly plastered houses in order to have a painted surface.
Always make your mist coat using a matt emulsion. If you use a vinyl-based paint, a skin will form on the plaster that will cause problems with peeling. Specialist paints such as Dulux Super Matt are a good choice to create a professional finish.
Once the plaster has fully dried, a coat of emulsion paint, acrylic paint, or oil-based paint will make your walls look amazing. Masonry paint can also be used but is best for rough walls that you'd have to sand otherwise.
Dulux Trade Supermatt is a top quality, economical, high-opacity matt emulsion which gives excellent coverage and application. Suitable for all interior wall and ceiling surfaces, particularly new plaster that is still drying out.
Plaster walls can be finished in any luster, from high-gloss to ultra-matte. The most versatile finish for most home applications is a satin finish that combines the soft warmth of a matte or flat finish with the ease of cleaning that comes with semi-gloss or gloss finishes.
The preparation needed for old plaster is mainly dependent upon the condition of the surface. If the plaster is clean and dry then it will require no preparation. However, if the plaster is powdery it will need to be treated with a coat of plaster sealer.
A mist coat should be left to dry for around 24 hours, even if it feels dry before this. Only one mist coat should be needed, but if you have some paint leftover that's already been watered down, you might want to add a second mist coat. As long as the first coat was dry, two mist coats will do no harm.
Freshly-plastered walls should be smooth on the whole but you may find the odd plaster splash or pieces of dust that have been left. Use a fine sandpaper and a brush to remove these blemishes but don't be too vigorous with your sanding.
Why is my mist coat not sticking to plaster? This might be down to a couple of things. There might be dust on the walls, creating a barrier. Your plaster might be too polished, in which case you might need to abrade it, or go with a different primer.
What is the best primer to use on bare/fresh plaster? Fresh plaster doesn't actually require a specific primer; instead you can use a mist coat which acts as a primer on this type of surface. Contract matt is ideal for mist coating as it allows moisture to escape out, but doesn't allow moisture in.
Preparing newly plastered walls
First and foremost, let the plaster dry. Paint won't adhere properly to wet plaster, so make sure it's fully dried. This takes around 3-5 days for overskim or 4-6 weeks for a new plaster wall, though it can take longer depending on humidity and ventilation.
Fresco is a mural painting technique that involves painting with water-based paint directly onto wet plaster so that the paint becomes an integral part of the plaster.
Dirt and dust can prevent the plaster from gripping the surface. With this in mind, it's a good idea to wipe your surface down before applying the plaster.
Too Much Water
You don't want to be too thin, but a mist coat needs to be thin—almost like a soup. The water will not seep into the substrate if the mist coat is too watery.
Another way to seal the plaster prior to painting is to apply a readymade sealer, Dulux make one specifically for new surfaces. I personally use acrylic stabilising solution, really made for stabilising chalky surfaces, but also excellent for sealing bare or new plaster.
Type: for the mist coat, use water-based emulsion paint. Avoid oil-based or vinyl paints, as they can create a barrier on the plaster, preventing proper absorption. Colour: a light or white colour is typically best, as it won't affect the colour of the top coats.
Due to the fact that newly plastered walls cannot be painted using certain paints until they are completely dry, contract matt is the best paint to use. This is for a number of reasons, which include cost and moisture.
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. Alternatively, you can use a water-based primer which saves you the mess of making a mist coat.
The most common problem caused by missing a mist coat is pealing paint, but sometimes it just bubbles. You may see it as you finish your decorating, or it might happen next time you decorate the room.
So watering down your first coat as a 'mist coat' will help the plaster to soak up the paint and create a bond between the new plaster and the paint. For new plaster it is critical that you start with a mist coat, which leads me quite nicely into my next section… what will happen if you don't mist coat!
Put simply, a mist coat is the first coat of paint that's put on bare plaster. Think of it as a base that's used to prime and seal the wall. Without the mist coat, the plaster will soak the moisture out of the paint like a sponge, causing it to crack as it dries.
Plaster generally takes around three to five days to dry fully. It will turn from a brown colour to pale pink. Then, you can apply your mist coat of paint or wallpaper. How long the plaster takes to fully dry can depend on how thick it is, and the conditions of your home.
Mist coat paint is simply watered-down emulsion paint, which acts as your primer. All you need to do is get some white emulsion paint and thin it out with water – it's that easy! Ten parts paint to one part water should work. If you don't fancy watering down your paint you can also use Dulux Sealer for Plaster.
Preparing new plaster for painting
Applying a mist coat can be messy as the paint is thinner than usual. Lightly sand the plaster with 120 grit sandpaper to remove any small imperfections and to key the surface. If the plaster is too shiny the paint won't adhere.
Choose a quality latex paint, like Benjamin Moore Regal Select, in any sheen and color you prefer. Eggshell and satin are popular finish choices for interior walls, but matte or gloss also work fine on plaster. Apply two coats for the best durability and color accuracy.