Master plaster; Newly plastered walls look great, but painting them can be tricky. Julia Gray offers five tips.
Byline: Julia Gray
Slow down for mist You first need to seal new plaster to make it less absorbent and to help the topcoat adhere better.
A common way to do this is with watered-down emulsion (known as a mist coat), as the plaster sucks up the water and becomes less absorbent.
After you've applied the mist coat, you'll be able to see where you need to fill more easily than you would with bare plaster.
Don't be a drip Watered-down emulsion is messy to work with because it drips much more than standard emulsion. Be careful to wipe, roller or brush-out drips immediately to avoid a bad finish - the paint dries quickly because the plaster's absorbent.
If your topcoat's white, it's best to use watered-down white emulsion for the mist coat, or you may end up doing more coats of topcoat than you need to.
Stain block is your friend Another problem with using a white topcoat on new plaster is that you can get patches of plaster the topcoat takes several coats to cover.
To save time and paint, use a stain block or a basecoat emulsion on these patches. Ronseal One Coat Triple Action Basecoat (from PS21 for 2.5ltr, B&Q) is specifically designed for new plaster (dilute with 20 per cent water for the first coat) and problem walls.
It seals the plaster and also fills hairline cracks, which sometimes appear in newly plastered walls and ceilings, especially if they're lath and plaster.
Other options exist Paints designed to be applied directly to bare plaster are available in DIY stores.
Although they're generally more expensive than watering down cheap emulsion, they're much nicer to use because they don't drip everywhere, but it can be harder to get a good finish with them.
Watered-down emulsion produces a 'soft' edge on new plaster, whereas bare plaster paints often produce a 'harder' edge that can adversely affect the finish, so it is advisable to water down the first coat, if you can cope with the mess.
Painting plaster before it's fully dry can cause the paint to peel, giving you endless problems, but some bare plaster paints allow the plaster to continue breathing and drying after the paint's applied.
The dangers of damp Sometimes patches of new plaster don't dry out because of damp. Often the best solution is to remove the plaster back to the brickwork and get a plasterer to do a waterproof render before replastering.
This should stop any moisture in the brickwork coming back through the plaster. The cause of the damp should also be addressed.
Alternatively, there are quick fixes, such as applying damp paint/ seal to the damp patches and then painting, or tiling or cladding the wall (with tongue-and-groove panelling, for example).
However, you're merely covering the damp rather than dealing with the problem and it may come through again once the damp paint/seal starts to fail.
After the plasterers have finished, it's important you remember to apply a "ghost coat" of watered down paint