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What is the best paint for lime plaster walls?

If you live in a period property that was built before 1920, it is likely the walls have been plastered with lime. It is a traditional material that dates back thousands and thousands of years. Do not rule it out on younger properties too, as it is still used today. In fact, it is an increasingly attractive option for those wanting more natural and environmentally-friendly materials.

Here, we will explain what lime plaster is and how best to paint over it.


Walls and Woodwork in Egyptian Grey™ No.154; Door in Messel™ No.39; The Country House Diaries @thecountryhousediaries

What is lime plaster?

Lime plaster is made of three simple ingredients - water, sand and lime (usually from chalk or limestone). You may find fibres like animal hair are added for extra strength. Because of these natural components, it is more eco-friendly than modern gypsum plasters. As it is a traditional material, you will usually find lime plaster on heritage buildings, but with our increasing desire for more eco-friendly products, lime plaster is being used on more new builds and contemporary properties too. It is an off-white colour generally, whereas modern gypsum plasters tend to be a pink colour.

There are two main types of lime:

Non-hydraulic lime: this comes from pure limestone. It comes in the form of lime putty and offers brilliant flexibility and breathability.

Hydraulic lime: this comes from limestone with natural impurities. It contains some setting agents. Available as a powder, it starts setting as soon as it meets water.

What are the benefits of using lime plaster?

Eco-friendly - both in its lower energy manufacturing processes and because it absorbs carbon dioxide.

Prevents damp - because it is breathable, air can pass through it and moisture can escape.

Improves air quality - think of it as a natural dehumidifier as it releases moisture back into dry air or removes it when necessary.

Long lasting - lime plaster actually gets stronger over time as it crystallises. Its tiny particles are able to get into all the miniscule gaps and form a strong bond.

Flexible - it is not brittle like cement, so it will adjust and will not crack like gypsum plaster can.

What paint do I use on lime plaster?

The key factor here is ensuring you choose a breathable paint (like Mylands). Lime plaster is permeable, so it allows your walls to breathe and it will not trap moisture (which can cause damp). To maintain the permeability, lime plaster walls need to be able to breathe. If you get moisture build up that is unable to escape, the wall paint will bubble and crack. The type of paint you useover lime plaster must be breathable and vapour permeable. It can be a natural mineral paint (silicate paint) or a breathable lime paint.

Limewash is a conventional finish that adds a layer of protection and some colour. However, it does require regular maintenance.

Conventional vinyl acrylic emulsion paints seal lime walls, keeping the moisture in. That can lead to structural damage and peeling paint. Lime walls are highly absorbent, so that moisture needs to escape rather than being locked into the substrate of the wall.

To work out how breathable the paint is, look out for the Steam Diffusion value (SD value). Properly breathable paint has an SD value of 0.01-0.05.

Mylands signature, Marble Matt Emulsion is a breathable paint. Its natural, mineral paint contains Carrara marble and natural earth pigments to deliver a wonderful texture, depth of colour and exceptional matt finish.

What is the best way to paint over lime plaster?

It has been quite a trend to show off exposed lime plaster walls as the final finish. However this look is not for everyone, and it does leave the wall without an extra layer of protection.

The first thing to remember when painting lime plaster is to ensure that it is fully set before applying paint. Not only does it have to dry, it needs to cure as well. This takes time - around four weeks if you use non-hydraulic lime. So, be patient as it will make all the difference to your final paint finish. That extends to any lime putty used on repairs.

Check for any lumps and bumps on the plasterwork and use fine sandpaper to remove them. Making sure this surface is well prepared, is fundamental to ensuring a sleek paint finish.

As mentioned above, make sure you choose a breathable, vapour-permeable paint. Check for natural ingredients as chalk and clay paints are more likely to be breathable. If you are working on exterior walls, it will most likely be made up of lime render which has similar properties to lime plaster. Again, you will need to choose a porous or breathable masonry paint to use.

It takes time to work with lime plaster. Not only to ensure it is fully set, but also because it requires multiple coats of paint. The general rule is a three coat approach, applying thin layers of paint and making sure it is completely dry before adding more.

The mist coat comes first. Thin down your paint with around 20% water for this layer. This coat facilitates good absorption and adherence to the plaster. Leave it to dry for up to four hours. The next two coats of paint can be full strength. Remember to allow drying time between paint layers to ensure the best finish.

The main consideration when painting over lime plaster is to ensure you use a breathable paint. And take your time. The best results require breathing (and drying) time.

Mylands recommends using its marble matt emulsion for outstanding results on lime plaster walls. 


Walls in Haymarket™ No.47 and Woodwork in Egyptian Grey™ No.154; The Country House Diaries @thecountryhousediaries 

Outstanding Qualities for Mylands Marble Matt Paint

  • Low VOC
  • Breathable
  • Natural ingredients
  • Mineral rather than chemical additives and fillers
  • Durability (to avoid frequent repainting)
  • Plant based products
  • Water based
  • Excellent coverage
  • Scrubbable and wipeable.