Everything to Know About Limewash Paint

Limewash paint is an eco-friendly and aesthetic option. Its antibacterial and antifungal properties make it ideal for those suffering from allergies. And, its broad range of colours and unique wash makes for a plethora of interior and exterior decoration possibilities.

Best of all, you can concoct your own limewash paint right at home. Find the recipe below, made with natural pigments found in Quebec.

Why choose limewash paint?

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Limewash Paint: A Natural Solution

Lime-based paint is primarily made from natural ingredients since it contains the following:

• Hydraulic lime, air lime (binder) 

• Clay, marble powder, pumice stone, sand (aggregate)

• Water

• Linseed oil

• Couma guianensis latex (bonding agent)

However, lime-based paint isn’t always entirely neutral. The reality is that, just like any other type of paint, the aforementioned contains a bonding agent, and the latter may vary from one paint type to another. In some cases, it can be natural latex, whereas, for others, it’s a PVA glue (polyvinyl acetate). As such, read the paint’s datasheet prior to purchasing it.  

What is the difference between air lime and hydraulic lime?

While looking into lime paint, the odds are that you’ll come across two types of said paint:

• Air lime-based paint

• Hydraulic lime-based paint

Both these types of lime meet distinctive needs. Aerial lime (air lime) stems from the purest of all limestone, given that less than 5% of clay impurities are tolerated. On the other hand, hydraulic lime contains between 5% and 30% clay. Despite their wildly different characteristics, both can be found in the limewash paint: 

Smooth vs. Granular Lime-Based Paint

Smooth lime-based paint can be applied as an intermediate coat, but also as a top coat, whether that be for interior or exterior use.

Granular lime-based paint has an aggregate like fine marble sand (0.5 mm grain, for example). Its application can even out slight structural differences, such as minor level defects or pores as well as fine fissures.

Granular lime-based paint differs from smooth lime paint on account of its application. Applied indoors, its application can be done as an intermediate coat and as a top coat. However, outside, granular lime-based paint can only be applied as an intermediate coat. 

Advantages of Limewash Paint

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Eco-Friendly Paint

The biggest downside of most paints (acrylic, epoxy, polyurethane, etc.) is that they release, more or less, large quantities of VOC (volatile organic compounds) into the air. VOCs are added for the following reasons: 

• Increase lifespan

• Improve freeze-thaw resistance 

However, when it comes to limewash paint, it meets very strict environmental requirements. So much so that it emits less than 0.008 mg/m²hr of VOC emissions into the indoor air.  

Yet, to know whether this product is truly eco-friendly, you have to delve deeper into its life cycle. Lime is extracted from limestone—calcium which makes up less than 3.6% of the Earth’s crust. As a result, it doesn’t come from a material that risks depleting over time. Even when discarded, limestone is biodegradable. 

Nonetheless, its environmental impact remains significant, especially during its extraction and production phases.

• Atmospheric emissions (CO2, SO2, NOx, dust)

• Energy use (electrical and fossil) 

• Water pollution and changes in aquifer regimes

• Environmental impacts (surface mining)

So should we infer that limewash paint isn’t all that eco-friendly after all? No, given that no paint is environmentally neutral. Without a doubt, health- and environment-wise, lime-based paint is a lot better compared to other paints. 

Bacteria- and Mould-Resistant Paint

Several characteristics ensure that lime has anti-bacterial and mould-resistant properties.  

• Separate cations from ceramic powder

• Mechanical destruction of cell membranes

• Powder-generated active oxygen

• High pH 

Tested on two bacteria stemming from digestive issues (E. coli) and respiratory problems (pseudomonas aeruginosa), lime naturally eliminates up to 99.9% of pathogenic germs. 

As for mould, it’s been shown, compliant with standard ASTM G21-2009, that mould is unable to develop. Limewash paint is therefore ideal for bedrooms since it prevents spores from growing on wall surfaces.

What are the downsides of limewash paint?

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Tricky Application

For a flawless application, several parameters must be taken into consideration: 

• Paint in temperatures between 8°C and 25°C (46.4 °F and 77°F)

• Shield it from direct sunray exposure

• Allow for a lengthy drying period 

For example, if the area in which the paint will be applied is on the colder side with high levels of humidity, limewash paint may reflect various degrees of sheen, such as a more glossy finish than first anticipated.  

The Fragile Side of Limewash Paint

Another drawback of limewash paint is its porosity. This characteristic renders the lime-based finish prone to stains. To bypass stains, applying Marseille soap to the painted surface before the paint dries is a must.  

This means that within 24 hours of applying the top coat, the limewash paint must be sealed with either wax or Marseille soap. This is what’s known as lime soap.

To do so, you have to use real Marseille soap, meaning a soap free of synthetic compounds. Forget about using liquid or neutral soaps that you might have in your kitchen or bathroom cupboards.

Marseille soap is then applied as a paint or coating. It will form a protective off-white patina coating. The coating’s colour ultimately depends on the soap’s concentration. The purer it is, the more the patina is visible. 

Making Limewash Paint

Basic Milk Paint with Lime Recipe

Beyond the list of compounds we detailed earlier in the article, you may be tempted to DIY your own milk-based lime paint. If so, note that there is a basic, go-to recipe that you can make at home:

• 1 litre of skimmed milk 

• 250 g of lime 

• 250 to 300 ml of linseed oil 

• 800 g of white chalk. 

Once all ingredients are whisked together, add 50 g of pigments to another container filled with water or milk. Add this last mixture to the previous preparation. You will then have 2.5 litres of homemade paint. 

Add Casein for a Stronger Hold

Why add milk to our homemade limewash paint? Because, said liquid naturally contains casein, an essential protein for milk’s nitrogenous components. This relates to dairy milk, not non-dairy milk, as the latter doesn’t contain casein. 

Note that casein dissolves in the alkaline properties of the acid hydroxide found in lime, which creates a substance with adhesive properties. Given the casein found in dairy milk, limewash paint made with milk has a stronger hold when applied. 

Can ovalbumin—the protein found in egg white—be used? The short answer is yes, but ovalbumin is likely only used as an adjuvant (to increase potency) in limewash paint specifically made for designing frescoes.   

Add Pigments for a Customized Colour Choice

Where can you get natural pigments? An art studio located in Sherbrooke, Studio d’art Shuffle, meets your needs in terms of eco-friendly arts and crafts materials, retailing local plants for dyeing purposes, that were once used specifically for colour, such as the following: 

• Crushed oak galls: From a yellow ochre to a dark grey

• Madder roots: From a golden hue by way of a shade of red

• Rudbeckia leaves: From yellow to green by way of a clear grey

However, note that if you want to make DIY dye for your paint, be mindful of the fact that not all oaks have dyeing properties. Use what’s known as the “yellow oak,” also called black oak or Quercus velutina. 

How to Prepare Your Canvas for a Limewash Paint Application

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Clean the Intended Surface and Apply a Primer

Start by scrubbing the wall to remove all dust or dirt that might prevent the lime paint from adhering to the intended surface. Feel free to use a biodegradable degreaser for cleaner results. 

Once the surface has been cleaned, apply a coat of casein-based primer. No need to reiterate the importance of casein. However, prior to applying lime-based paint, allow the primer coat to dry completely. 

Naturally, if the wall in question is covered by wallpaper, remove it first. Don’t apply the casein primer directly atop the wallpaper or onto the leftover glue coating the wall.  

Dampen the Surface

Once the wall is clean and coated in a primer, you can spray the surface generously with water the night before you intend on painting. Naturally, it’s best to work in a cool environment to foster better adherence by way of a damp application. 

Limewash Paint Application

How to Brush-Apply Limewash Paint

Start by using the right tools. Indeed, the brush used must absolutely be one with natural bristles. Lime paint won’t adhere to synthetic fibres. Proceed by painting the corners and angles with a paintbrush, then use a brush to apply two coats of limewash paint:

• first by proceeding with horizontal strokes;

• then with vertical strokes.

However, avoid applying the second coat before 24 hours have elapsed, ensuring the surfaces are always damp. If the final outcome doesn’t appeal to you, feel free to add another coat—or as many as it takes—until you achieve the unique, desired result. 

Keep in mind that the paint will appear denser once dry.      

How to Apply Limewash Paint Using a Roller

To avoid paint streaks, a traditional, roller-applied method is best. When using limewash paint, use quality rollers with long and natural fibres. 

Apply a primer in vertical strokes one next to the other, then cut across with horizontal strokes. Proceed with vertical strokes again, as well as horizontal strokes for a thicker base coat, concealing any streaks. 

After four to six hours of drying time, apply limewash paint with a small, long-fibred roller in criss-cross motions. Your strokes must be: 

• Short and irregular 

• Up and down 

• Left to right  

The right technique will allow you to create colour nuances or shade variations.

When the paint is no longer damp and glossy, you can go in with a rubber spatula to remove any irregularities found on the surface. Finish it off by applying a protective coat, such as that of the Marseille soap technique mentioned above.   

Painting Different Surfaces with Limewash

Speed-Painting an Interior Wall with Limewash

Besides what we already detailed regarding the proper limewash paint application steps, you can always use an alternative technique: an airless paint sprayer.

A paint sprayer guarantees a swifter application; one that’s just as appealing, but the spray gun in question must be powerful enough to be fitted with a large nozzle to prevent it from clogging. The airless sprayer gun used must be powerful, with no less than a 200-bar air pressure.

To avoid clogging your gun and strainer with paint, choose a 30-mesh sprayer bag. As for the nozzle, 525 and 531 are ideal for all limewash paints, no matter the brand. 

To ensure functionality, the airless spray gun must be powered by a compressor with a flow rate of under three litres per minute. 

Painting an Exterior Wall with Limewash

As we already mentioned, air lime requires favourable weather conditions when applied. Given that this sort of paint is slow to hold, it must be shielded from humidity. Have the following tools and equipment on hand when applying such paint:

• Bucket

• Limewash paint

• Water

• Mixing rod

• Large paintbrush

• Trowel

• Tarp 

Use a tarp to protect the ground as limewash paint stains are hard to wipe clean. Naturally, if you’ve planned your painting project for a specific weekend, yet rainfall is forecasted for those days, postpone it to a later date. 

As for the first coat, the right dosage should be equivalent to one part lime for every two parts of water. However, proceed carefully as the mixture is likely to change proportions based on the natural pigments added. Test out the paint prior to executing. 

The lime should be poured in like a fine mist, all the while mixing to prevent lumps from forming inside the bucket. The final consistency should be like that of a crêpe—not pancake—batter. To ensure your mixture is ready for use, dip your finger in it. If the paint sticks to your skin, it’s ready. Don’t forget to clean your hands afterward; limewash paint is caustic and especially harmful to the skin.

Now then, the only remaining step is applying several coats on a smooth and damp wall, until you achieve the unique outcome you’re looking for.

Last pointers: 

• Mix your paint in figure eight motions (smoother)

• Paint the entire surface at once (to avoid slight colour discrepancies)

• Avoid painting outside the intended surfaces (otherwise, wipe them clean immediately) 

• Wait 24 hours between coats 

Naturally, since the paint needs to be mixed whilst painting, you’ll need to be two. 

Limewash Paint Makes for a Truly Stunning Home

Limewash paint isn't just any old paint slapped onto your walls, coating them in colour. It’s a timeless, durable, and eco-friendly aesthetic fusion. Besides said paint’s breathability and ability to uniquely transform the vibe within a living space, it tells a story of artisanal traditions and eco-consciousness. Whether you’re looking for a Mediterranean splash or a rustic vibe, limewash paint offers an infinite pallet of possibilities to spruce up your home. By adopting this nuanced and chalky paint, you’re not only investing in your home’s aesthetic appeal but also an eco-conscious and sustainable lifestyle.