How to Make Natural Lime Whitewash

How to make whitewash

In this video, we are going to learn how to make a hydraulic lime based whitewash. Whitewash is a mixture of water and lime into which you can add colour pigments. This mixture is an eco-friendly alternative to paint, and can be used either for decorative purposes or as an overcoat on many types of surfaces.

To make whitewash, we will need colour pigments, alum salt, white natural hydraulic lime (type NHL 3,5), water, a tub, a brush, a bucket, a hose for irrigation and gloves.

Colour pigments

Alum salt

White natural hydraulic lime (type NHL 3,5)

Water

Tub

Brush

Bucket

Hose

Gloves

In this case, we are going to whitewash a rough concrete fence.

Begin with cleaning the whole surface you are going to whitewash. You can use a high pressure cleaner or a wire brush to do that. The surface has to be perfectly clean and free of all moss or lichen.

Moisten the surface 24 hours before you start coating so that water penetrates deeply through the base. If the whitewash is applied on a dry base, it will not adhere well to the surface and it will become a flour-like substance.

We are now going to prepare the whitewash.

For each litre (34 oz) of white hydraulic lime add 2 litres (68 oz) of water (1 litre of lime to 2 litres of water). If the water and lime are mixed in this proportion, the mixture will have a smooth texture and it will cover the base completely.

If you want to colour your lime, use pigment colours. For each kilogram (2,2 Lb) of lime add about 50g (0,1 Lb) of pigments.

For each kilogram (2,2 Lb) of lime add 50 g (0,1 Lb) of pigments.

Feel free to do a pre-test in order to check the final texture. Remember that when the mixture dries, it looses 50% of its colour.

Add the alum salt so that the mixture and the pigments bind well. For each kilogram (2,2 Lb) of lime add 100g (0,2 Lb) of alum salt.

For each kilogram (2,2 Lb) of lime add 100g (0,2 Lb) of alum alum salt.

Mix well to obtain a homogenous mixture.

Begin with coating the angles with a round brush.

Apply the whitewash to the rest of the fence by moving the brush as if you were writing the number 8. This technique is called "papillonnage" (from the French word butterfly). It eliminates traces of brush and allows the coat to be uniform.

Stir the mixture regularly in order to preserve the homogenous consistency. If your mixture isn't stirred correctly or if you don't master the application technique yet, the paint will run. If this happens, mix the whitewash again and give it another brushstroke before the mixture becomes dry.

Let it dry for 24 hours. Once the whitewash is completely dry, the colour becomes uniform.

Now it is time to apply a second layer, following the same method.