painting new plaster

How To Paint New Plaster

Painting new plaster is a key step in transforming your home decor. Fortunately, producing a nice smooth finish in the colour you love is a relatively simple and cost-effective way of giving your home a stunning new look.

Before you get started though, there are three common questions that DIY enthusiasts often ask when it comes to painting new plaster:

  • How long should I wait for the plaster to dry before painting?
  • What type of paint should I use on new plaster to get the best possible finish?
  • Should I seal fresh plaster with PVA?

In this post, I'lll tackle all these questions and more.

Please note that this article only deals with painting INTERNAL walls and ceilings.

Cost

Time

Difficulty


Tools & Materials

Tools

  • Canvas drop cloth to protect carpets
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    Scraper
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    Bucket
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    Stirring paddle drill attachment or stirring stick
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    Paintbrush set 
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    Roller and tray (medium to tight roller sleeve)
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    Filling knife

Materials

  • Plastic sheets
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    Rosin paper to protect hard floors
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    Masking tape
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    Emulsion paint
  • Solvent-based paint for kitchen and bathrooms
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    PVA as a sealer for solvent-based paint only. For emulsion paints, use mist coats (see mists coats below)
  • Filler
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    220-grit sanding block

What Paint Should I Use When Painting New Plaster?

Picking the right paint depends on the room you're painting, the plaster type and your budget.

The humidity in kitchens and bathrooms cause water-based paints (emulsions) to soak up the water vapour, which can make them unstable and likely to peel or harbour mould spores. Therefore, it's best to use solvent-based paints for kitchens and bathrooms. Some companies even make special kitchen and bathroom paints which come in a vast range of colours.

For the other rooms in your home, go with good quality emulsion paints. A good quality paint will need less coats, last longer and produce a much better finish when compared with cheaper paints. Use this link to find the best options for your home.


Step-By-Step Instructions

Wait For New Plaster To Dry

Freshly plastered walls must be left to dry out completely before you start painting.
Drying time depends on several factors such as; time of year, central heating, plaster type and the number of plastered layers.

However, you can expect the plaster to be completely dry after about three weeks, but this assumes you have central heating. If you don't have central heating, it could take up to 6 weeks.

A freshly plastered wall is much closer to the colour in Fig.1 than Fig. 2 (see images below). Once the wall is completely dry, the wall should match the colour in Fig. 2. and be uniform in its colour.

freshly plastered wall

Fig. 1. Colour of a freshly plastered wall (do NOT paint!)

dry plastered wall

Fig. 2. Colour of a dry plastered wall (ready to paint)

Why Do I Have To Wait For New Plaster To Dry?

You shouldn’t paint plaster before it's completely dry because paint forms an airtight skin on top of the plaster. 

This airtight skin results in moisture being trapped underneath the paint instead of evaporating off the plaster. Trapped moisture will either move deeper and develop mould in the wall, or will mix with wall salts and become Efflorescence.

In either scenario, you’ll have an expensive problem to fix. As always, prevention is better than cure!

Can I Speed Up The Drying Time?

Make sure freshly plastered rooms are well ventilated by opening doors and windows. This will allow natural air ventilation to flow through the room, gently drying your plaster.

Don’t be tempted to turn the heating up full whack, as rapidly drying plaster can cause cracking.

Prepare The Room For Painting

All the prep work listed below should have already been done for the plastering process. However, just in case they haven't, here are the essential steps:

  • Move as much furniture as you can out of the room. Any furniture that needs to stay must be covered with plastic sheets
  • Cover hard floors with rosin paper and cover carpet with canvas drop cloths
  • Use masking tape to cover other areas that shouldn’t be painted

For much more info on how to prepare a room for painting, please check out my guide to Painting A Room With No Mess – 27 Top Tips.

Remove Excess Plaster (if necessary)

Look closely at the surface and you will most likely see unwanted little blobs and drops of plaster. They are not so obvious at first, but they stand out later when you’ve finished painting. Use a scraper to remove all the bits you find.

Sealing New Plaster

Fresh plaster is extremely porous, so if you use undiluted paint, the paint’s moisture will be sucked up by the plaster. The result is dry paint that won’t bond with the plaster.

Therefore, you must seal the plaster before applying the finish paint. For water-based paints, seal the plaster with a mist coat. A mist coat is a diluted coat that the plaster will suck up like a sponge and fill its pores.

For solvent-based paint (used for kitchens and bathrooms) use PVA as your sealer.

How To Create And Apply Mist Coats

Important Note: Make sure that you do NOT use a vinyl emulsion for your mist coat. Vinyl emulsion forms a skin on the surface of your plaster that will be prone to peeling.

As mentioned above, solvent-based paints should be sealed with a PVA adhesive and NOT a mist coat. PVA should also be mixed with water and by the same ratio as below.

1. Mix Emulsion With Water 

  • Mix emulsion with water. The ratio should be four-parts emulsion to one-part water.
  • Stir thoroughly using a stirring paddle attachment for your drill. If you don’t have a stirring paddle attachment, just use a regular stirring stick.

Note: Depending on your emulsion, you may have to alter the above ratio to achieve the right mix. If you need more info, check out this mist coat guide.

2. Apply Mist Coat On Walls

  • Apply emulsion-water mix to the plastered surface. Use a brush for edges and a roller for everywhere else.
  • Check that the plaster is absorbing the liquid. You may even hear a sucking sound while the plaster is absorbing the mist coat
  • If you find that the plaster is not absorbing the mix, add more water to a max mix of 50/50
  • In most cases, one mist coat is enough. However, it doesn’t hurt to add a second one if you feel the need to.

Fill And Sand Any Imperfections

Once the mist coat has dried, imperfections should be filled and sanded down.

  1. Mix up some filler
  2. Using a filling knife, apply the filler to any holes and cracks you find
  3. After the filler has dried, use a 220-grit sanding block to smooth it
  4. Touch up the filled areas with the mist coat mix 

Paint Wall With Finish Coats

Once the filler touch-ups have dried, your wall/ceiling is ready for its finish coats.

Apply two or three finish coats by following the same steps used for the mist coat

For more information on painting, please check out this article, under the heading ‘Painting Technique’. You'll find some great tips on how best to use rollers and brushes, so I highly recommend you check this out before you start painting.


Final Thoughts

I hope you found this post useful and now feel empowered to paint your freshly laid plaster. If you want to see how the pros do it, check out this video: 

If you've enjoyed reading this guide, please share it using the social share buttons and leave a comment below. Thanks!

About the Author Russ

I'm the founder of PropertyWorkshop.com, a site dedicated to sharing home renovation and repair tips. To learn more about me, please check out our About page