If you live in a period property, there’s a good chance you have lime plaster on your walls. Before the 1920s, most British homes were built using lime mortar, lime render and lime plaster. There’s even evidence of lime being used by the Ancient Egyptians and Romans.
It may be a centuries-old material, but lime’s not been banished to the history books. In fact, as more of us look for more environmentally-friendly materials for our homes, lime plaster’s enjoying a revival.
So, what’s the best paint for lime plaster? Here’s what you need to know before you start decorating.
What is lime plaster?
Let’s start with the basics. Lime plaster’s a traditional building material made from sand, water and lime (usually from chalk or limestone). In essence, it’s made by burning limestone, then slaking it with water to form a plaster that hardens with age. When fully cured, it’s extremely durable and hard-wearing.
Unlike modern gypsum plaster, lime plaster is highly breathable and flexible. It can absorb and release water vapour, helping moisture move naturally through the building fabric. It’s lime plaster’s breathability that can help to improve your indoor air quality and prevent mould or damp on your walls.
But if you cover lime plaster with the wrong type of paint, you can seal the walls, reduce their breathability and cause problems like damp patches, bubbling and peeling paint.
Why does lime plaster require breathable paint?
Lime plaster is naturally porous, allowing water vapour to pass through it. To maintain this breathability, you need to coat it with a paint that allows moisture to move through it too.
Not all paints are breathable. Some conventional paints can create a less permeable layer over the plaster. That can prevent moisture from evaporating naturally. As a result, you may experience damp walls, bubbling, flaking or peeling paint.
That's why a highly breathable paint is the best choice for lime plastered walls. It works with the plaster rather than sealing the surface. It helps your walls continue to manage moisture naturally.
Which paint is best for lime?
You need a breathable paint for lime plaster. Your best options are traditional lime wash or distemper, or more modern clay paints.
Lime wash
Lime wash is a traditional, highly breathable covering that’s been used on lime plaster for centuries. It soaks into the surface rather than forming a film on top, helping lime plaster retain its natural breathability.
Its microporous, alkaline properties deter algae growth. Many traditional builders and conservation specialists recommend lime wash because it’s an authentic finish for lime plaster. It creates a distinctive soft, matt look that suits the character of older and period properties. Limewash paints are tinted with mineral or natural pigments to add more colour.
The main drawback of limewash is the level of maintenance involved. You’ll need to apply several thin coats for a decent finish. And it requires more regular upkeep than modern paints.
Distemper
Distemper’s typically made from chalk, water and a natural binder (such as animal fat). Like lime wash, it’s another traditional paint that gives an authentic finish. It creates a soft, matt effect.
However, distemper tends to be less durable and more difficult to maintain than modern alternatives.
Claypaint
Unsurprisingly, claypaint uses clay as its key ingredient. Claypaint has a very high level of breathability that’s fully compatible with lime. Unlike paints that create a more sealed layer over your walls, clay paint’s porous finish allows moisture vapour to pass through freely.
Claypaints are far more durable than lime washes, lime paints and distempers. Plus, it’s available in a wide range of colours too. Its thick, creamy consistency helps to smooth out any hairline cracks or flaws in the surface. The result is smooth, long-lasting paint finish.
How to paint interior lime plastered walls with Claypaint
Claypaint’s our most breathable paint for interior walls and ceilings making it ideal for lime plastered walls. It’s also virtually VOC free with no nasty odours or emissions.
Here’s how to apply it to your lime plastered walls for the best result:
- Check the surface: Make sure your bare plaster’s fully cured, stable and free from loose or flaky material.
- Prepare powdery walls: If you're working with older lime plaster that feels powdery, use a suitable breathable stabiliser such as Earthborn Wall Glaze.
- Dampen the wall: Lightly moisten the plaster immediately before painting using a damp cloth, paintbrush, roller or water spray bottle.
- Dilute your first coat: Apply a mist coat. That’s a diluted covering of around 20% water added to your Claypaint. This helps prevent highly absorbent lime plaster from drawing moisture out of the paint too quickly.
- Apply your second coat: Once your first coat’s fully dry, apply one or two full coats of Claypaint using a short pile roller for a smooth, consistent finish.
About our highly breathable Claypaint
Earthborn Claypaint is breathable and water-based. It’s Sd value is only 0.02m, meaning it’s highly vapour permeable.
Its Moisture Vapour Transmission Rate (MVTR) is 1115 g/m² per day. That’s the amount of moisture that can move through a surface over a 24-hour period.
For more details, check our Claypaint data sheet
What about exterior lime walls?
For exterior lime walls, choose a breathable masonry paint that allows moisture vapour to escape rather than trapping it within the render. Traditional lime wash is one option. It’s been used on lime-rendered buildings for centuries. However, it needs plenty of maintenance as it often flakes over time.
For a more durable alternative, look for a breathable exterior paint designed for use on lime render. Earthborn Silicate Masonry Paint is a highly breathable mineral paint which is a viable alternative for external lime substrates. Used with our Silicate Primer, our silicate paint creates a long-lasting finish for your exterior lime walls.
FAQs
Can you paint directly over lime plaster?
Yes, but your new lime plaster must be fully cured before you paint it. Lime doesn't dry like modern gypsum plaster. It needs time to cure, on top of drying time.
As a general guide, allow around four weeks of curing time for every 5mm of plaster thickness (sometimes longer). Your lime plaster supplier or plasterer should be able to advise you on your particular walls. Don’t apply further coatings - lime wash, paint or any other product - until it’s had sufficient curing time.
Once the plaster’s fully cured, make sure the surface is sound and stable. Fill any hairline cracks or small holes with lime putty or a breathable filler. Only then, should you start to apply breathable paint.
Can I use regular emulsion paint on lime plaster?
Modern emulsion paint is often acrylic or vinyl. Whilst it’s hard-wearing and washable (ideal qualities in busy homes), it isn’t always breathable. Lime plaster needs to breathe.
When moisture gets trapped inside your walls because of a non-permeable paint covering, it pushes outwards. That’s when you get bubbling, peeling and flaking paint.
Always check the levels of breathability and water vapour permeability on paints for lime plastered walls.
Breathable paint for your lime plaster walls
Breathable paint is the perfect companion to lime plaster walls. If you’re updating your period property or want to improve your indoor air quality, breathable paint is a great option.
Try Claypaint, our most breathable paint for interior walls and ceilings or Silicate Masonry Paint for exterior wall paint.
Order a sample pot to try out our paint colours.
