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.
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.
It's perfectly fine to paint over new bare plaster. Firstly you will need to apply a mist coat (thinned down emulsion) this is a very important step, it needs to be able to sink into the absorbent plaster and needs to be thin and not leave a roller texture on the wall.
Before you can paint a newly plastered wall, you need to add a primer and undercoat. If you skip this step, the plaster will soak up the paint like a sponge, so you'll need to add more coats than you might otherwise need to.
Without the mist coat you're likely to have very poor adhesion between your paint and your plaster and quite often it will crack, flake or even peel off in sheets in some instances!
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.
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.
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.
If you've plastered yourself, or if you can see a few spots and bumps (which could be a splash of PVA or plaster), you can lightly sand these back to avoid them showing up once you've painted. Overly sanding the surface will create additional shine, not ideal for adhesion when you start to apply the paint.
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.
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.
Placing drywall over plaster is possible. You must secure drywall to wall studs with screws.
Once the plaster has cured and dried, you can start painting and decorating. Before applying paint, you should prepare the walls by sanding down any rough areas and dusting off any debris. Use a primer to ensure the paint adheres properly to the plaster.
The best kind of paint for plaster walls is whatever color appeals to you! Once plaster walls are properly patched and primed, they can easily take any color or finish. Satin and eggshell finishes are very popular, and lighter, neutral shades of cream and white are ideal if resale value is a concern.
Let the plaster dry
The very first thing you need to do when painting new plaster is to let it dry. A week should be long enough to let it completely dry out and for all damp patches to disappear. Once the plaster is dry it should be light with no dark spots and a consistent colour and appearance throughout.
Before painting your wall, you need to let the plaster dry completely. Painting over plaster when it's not dry can cause problems later, so if in doubt, always wait until you're confident it's dried completely.
What Causes It? Peeling from plaster could be a result of insufficient wet troweling of the white coat when the plaster was originally applied, causing chalking of the surface. Very hard plaster may be slick, reducing the adhesion of any coating.
There are two methods to sealing the new plaster. Firstly, you can use a mist coat of white watered down emulsion. However, it is more preferable to use a primer or top coat and water down the first layer by 10%. This allows the initial coat to properly soak into the plaster aiding adhesion of the final coat.
Preparing Your Room For Painting
Check for imperfections such as cracks, indents or raised areas on the plaster. Repair with Polyfilla and once dry, sand them down from top to bottom with a light 120mm sandpaper to make sure the surface is smooth. Remove any dust, grit or oil from the surface.
Masonry, Brick, Stucco and Plaster: KILZ ORIGINAL Primer may be used on clean, dry, aged masonry surfaces that have cured (dried) at least 90 days.
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.
Start by cleaning your surface before removing any loose paint and rust with spirits and sanding. Repair any holes or imperfections with a metal putty, wipe the surface clean and begin priming. Apply evenly on a dry and non-windy day if working outdoors.
The main reason why paint cracks is due to poor preparation on fresh plaster. Fresh plaster needs to be totally dry prior to applying paint. It also needs to be primed before adding emulsion.
Can you use Zinsser Peel Stop on bare plaster? You can, yes. Some Decorators I know use Zinsser Peel Stop to prime plaster walls before applying emulsion.
Medal Bonding Liquid is a solvent-based primer and sealer, which has been specially formulated to provide excellent penetrating properties for adhesion to very porous surfaces.