I painted our lime-plastered walls myself and now know you need to do these 5 simple things to ensure a good result

In my quest to slowly renovate our 1700s cottage, one of the biggest endeavours my partner and I took on was changing the dark and dated kitchen into a bright bedroom. Not only did this involve removing all of the usual cupboards, extractor fan and electric hob cables you would expect to see, but we also had to chip away concrete render that had been applied to level the cottage stone walls.

As any conservationist will tell you, traditional stone walls need to breathe. Their design hinges around water from the exterior walls penetrating the porous lime before drying back out again. This can often lead to darker patches that worry a lot of homeowners.

It was deemed in the 1970s to 2000s (and even today) by builders that the best practice was to inject a chemical damp proof course and use cement instead of lime render for the plaster, meaning the walls were suffocated. Naturally, this led to more damp.

Which brings us to the present day when the room is more or less complete. The fresh lime plaster looks incredible and really does restore that wibbly wobbly charm of workers’ and farmers’ cottages. But while I love the charm, it did mean that there was a lot more involved in how we decorated the room compared to decorating on gypsum with regular emulsion paint. It still counts as an easy DIY project though, and didn’t take much longer than a run-in-the-mill paint job, but here’s what I learned to get the best results.

1. You need to prep correctly — but not the normal way

Unlike painting a plastered room, which needs to be sanded, fill and sanded again until the walls a lovely and smooth, ready for the fresh coat of paint, lime plaster does not need to be sanded. In fact, please, please do not sand lime plaster. The dust particles that sanding creates actually clogs up the natural pores of the plaster and means it won’t do its job as efficiently.

Instead, I used a stiff natural bristle brush to sweep off the remaining dust from the walls and to inspect it for any cracking that may have occurred during the drying process. Lime plaster needs a lot of time to dry properly and it is fascinating to watch it change colours as it does. I used a small amount of fine lime putty on my finger (with gloves) and rubbed it into the hairline cracks that showed once the plaster was a completely uniform cream colour. A sponge can be used to ensure there are no bumps between the dry and fresh plaster. After that dried, I brushed the walls again.

2. You must use the right type of paint

There would be absolutely no point in taking the time to remove the concrete render and replaster using lime just to cover it back over with a synthetic polymer acrylic or vinyl paint that makes up the majority of emulsion paints.

Breathable paints are typically made using lime or clay to allow vapour and moisture to pass through. There are some fantastic brands out there that offer various types including:

• Distemper, a chalk/lime based paint, that works great for a chalky traditional finish. Little Greene and Farrow & Ball both do distemper paints
• Limewash, a paint made using slaked lime, with a thinner, more transparent appearance. Try Epodex or Limewash.com
• Mineral emulsions, an eco-friendly version of what you would typically see in the shops, for a more solid, durable use. Try Brewers for options.

We opted for a mineral emulsion from Edward Bulmer because I really wanted a vibrant yellow in this space to cheer up the sometimes dull light it receives. I think we will use lime wash and distemper elsewhere in rooms that suit those finishes.

3. Don't skip the mist coat

Similarly to brand new gypsum plaster, lime plaster has to have a mist coat applied before the real paint work can begin. However, unlike gypsum plaster the lime walls should be pre-dampened. I used a pump action sprayer for this, but you could also use a really saturated sponge. This wetting stage is really important is it will help the paint bond with the plaster, otherwise you might have issues with cracking or crumbling later on.

Many paint manufacturers, including the one we chose, advise using a primer on fresh plaster and I'm sure that would make a difference, but with a limited budget, a DIY mist coat will have to do. Perhaps I will run an experiment on my next room to compare the finishes of with and without.

For the mist coat, I mixed two parts paint to eight parts water in a bucket just using a clean plastic food container box to eyeball the amounts. A decent mix and I was ready to go!

4. Use natural tools for the best result

Now this might be a little preachy of me, but I do honestly believe that if you’re aiming for conservation and restoration, doing things the traditional way might be slower and more arduous, but it also produces a more delicate and accurate finish.

So, I hand painted the entire room using a brush with natural bristles, like this 38mm paint brush from B&Q. While Edward Bulmer (where I bought my paint) suggests you can use a medium-pile paint roller, I just didn’t want to ruin the delicate nature of the lime plaster by putting too much pressure on it by rolling, or end up with train tracks in awkward to reach spots. The natural bristles were much kinder on the lime and using a rather enthusiastic crisscross pattern across the walls, it gave a sense of movement to the space and it looks gorgeous.

5. Let lime be lime and use thin coats with plenty of drying time

When painting a modern house, we all just want to get in and get out of the job of painting as fast as we can, ideally over a weekend. But that just doesn’t fly with lime. To get the best results lime plaster rewards patience.

On top of the mist stage, I used thin coats to build up the colour to ensure the pigment was incredibly rich. The yellow turned out better than I ever could have hoped for and the variations in tone really display the difference from a flat surface and a solid application.

How will I use these lessons learned moving forward with the renovation?

We still have three rooms and a staircase to plaster and paint before we are finished with this project but I’m so glad I used a mineral emulsion as my half-way house to get used to breathable paints. We will be using limewash and distemper for the other rooms so it will be interesting to see how those types compare.

I’m also going to invest in differently sized brushes to make my life a little bit easier going round corners and edging against beams and door linings. That said, if the other rooms come out as interesting-looking as this first room, the renovation will have been so worth it.