TRADITIONAL RECIPE

WHITEWASH PAINT

Introduction

Sometimes called lime slurry, in France Badigeon. It is prepared with water and hydrated lime, also named slaked lime, lime hydroxide, pit lime, and which

formula is Ca(OH)2. This is obtained extinguishing the quicklime (CaO).

This type of paintings are natural but also disinfectants, they allow walls breath

and are resistant because the lime contained, reacts with the CO2 from the air, to be transformed onto a calcium carbonate; and anchor on plaster surfaces or mortar.

Ca(OH)2 + CO2 CaCO3 + H2O

The action of sunlight does not degrade this coating as it happens with modern paintings whose binders are organic resins.

The disinfectant effect of the whitewash when painting wood, protects it from bacterial growth as it raises the pH of the water contained on the wood.

It is also used to disinfect walls, basements, wineries, farms, etc.

The base composition of this painting is hydrated lime and water. Depending on the degree of transparency or coating required, proportions will be as follows:

In volumen In weight Hydrated lime 1 part 1 part Water 2 to 5 parts 1,6 to 4 parts

When possible, dosing hydrated lime should be done by weight rather than volume, because being a powder it could differ depending on the settlement degree.

Coating stability is improved by adding vinyl glue (white wood glue) on a 2% dosage of the total water amount.

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Pigmentos en polvo Easycolor® ,para pinturas, cementos, cales, bellas artes, etc. Fabricados por G&C Colors, S.A.

Recetario tradicional uso Easycolor. Pintura a la cal. Mayo 2012 V.0 Página 1 de 4 To colour this paint we will use pigments. If we want to improve their moisture and dispersion, we will add a 0,05% of liquid soap of the total grout (it will provide a better smoothness and flexibility) or adding Calgon. This contains moisturizing substances such as hexamétaphosphates dispersers, polycarboxylates or both. Soap and Calgon could be used in solid or liquid form but the liquid will be easier.

As for the pigments being, depending on the intensity desired we will dose up to 10% of lime weight when using synthetic pigments(1) (Easycolor® range), or 25% if we use earth colours(2).

To shake the slurry we can use a simple wood stick but we will obtain a better performance if we use an electric mixer. If we filter after mixing and dispersing all the components, we will remove any lump that could become a defect when the coating is dried. For that purpose we can use a fine sieve, an elastic stocking, etc.

The slurry we have obtained is ready to be used, although it should be advisable to let it rest to eliminate any air bubble appeared during the mixing of the grout, and therefore get a perfect finish.

The product could be stored as the hydrated lime slurry does not harden with

water but when exposed to the air from which it takes the CO2 as mentioned previously ( relative moisture between 55 and 65% preferably).

We should bear in mind that pigments are not soluble, and therefore, when we stop stirring they will start a more or less quick sedimentation depending on the lime slurry concentration, that is, how thick it is. For very dilute slurries or after a long time, it is advisable to stir again to homogenize the product before applying a second coat. Sometimes, it will be sufficient to stir the product with a paint brush.

The slurry does not incorporate any slipping additive to minimize the dripping effect that could come on the support, so the product will be applied with a flexible brush from up to down.

We will apply a first coat to wet the support. 2 or 4 hours later, a second coat will be applied. This second coat is called “al fresco”. If we wait for more than 24 hours, it should be advisable to moisture the wall. In that case the application is called “in dry”.

Playing with the amount of water of the grout we will control the transparency or opacity degree as well as the tone in case we had used pigments. We will be able to combine, on successive coats, different intensities or combination of colours.

In general terms, paints al fresco offer degraded or pastel tones. It is possible to enhance the tone and give a golden hue if we use a preparation made of beer. For it, you should only need to prepare 1 part of pigment for 5 of beer without gas.

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Pigmentos en polvo Easycolor® ,para pinturas, cementos, cales, bellas artes, etc. Fabricados por G&C Colors, S.A.

Recetario tradicional uso Easycolor. Pintura a la cal. Mayo 2012 V.0 Página 2 de 4

Practical example of whitewash paint:

INGREDIENTS QUANTITY Slaked Lime 1 Kg. Water 4 litres. Yellow pigment 0,5Kg. (one bag of Easycolor 952) White glue 80 c.c. Soap in liquido or Calgon 2 c.c.

The recipe:

1. In a bowl put 2 litres of water and pour the liquid soap or Calgon. Mix gently to dilute and avoid foam. 2. Add the pigment and mix with an electric mixer. We will avoid foaming if we keep the mixer completely submerged while it is rotating. We will adjust the speed and dimensions of the recipient to ensure the complete immersion of the propeller avoiding it come up. 3. In another container, we will pour the remaining 2 litres of water; we will mix and gently add the lime to avoid clumps that could not be disgregated later on. 4. We join the content of the two previous recipients and stir gently to a complete homogenisation. 5. We add the glue and stir till homogenisation. 6. Filter to remove lumps.

Another recipe used in France is:

1st coat:

INGREDIENTS QUANTITY NOTES Water 4 litres If to be applied inside, you will put 3 litres of water + 1 litre of semi-skimmed milk. Slake lime 2 Kg. It is gently added while stirring the preparation. Potassic alum 125 gr. It acts as a fixer for the pigment.

This first coat is always applied from up to down and in 45º cross. Let dry for one day.

2nd coat:

It will follow the same composition as the first coat, but adding earth colours or 200grs of synthetic pigment. If used outdoors the brush will go, instead of up to down, only vertically, so as to avoid rain smudges. Some applicators also add 250grs of talc to gain volume.

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Pigmentos en polvo Easycolor® ,para pinturas, cementos, cales, bellas artes, etc. Fabricados por G&C Colors, S.A.

Recetario tradicional uso Easycolor. Pintura a la cal. Mayo 2012 V.0 Página 3 de 4

Pathology of flour formation that peels off and spots.

This problem could arise from a mistake in the dosage of the preparation of the grout and also because the application was made on inappropriated supports, if those are not enough or too porous; and also because the support was not dampened enough before applying the grout. Keep in mind that the best support will be always a lime plaster.

A way to solve the problem without renewing all is to prepare a fixing milk based grout. You take 1 volume water and 1 volume of semi-skimmed milk. The milk casein will act as a fixative and will not alter the original matt tone. If any clear liquid wax is used, there will be probably an excessive porosity closure, so as not to allow the wall to breath and will with the passing of time generate moisture problems besides transforming the original colour into saturated.

(1) Synthetic pigments are obtained artificially although some of them are naturally obtained. We can mention as the commonest: yellow, red and black iron oxides and their combinations, titanium dioxide (white), green chrome oxide, ultramarine blue, and a long etc.

(2) Earth colours are pigments extracted directly from nature. The main group consists on ochres that are yellow, red, brown and black iron oxides that have taken their name from the county where there are deposits. We can underline the following colours: Siena, Calcined Siena, Shadow, Calcined Shadow, Yellow Ochre, red Almagra, etc. The colour earths have less tinting power than synthetic pigments as well as shades are also less clean.

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Pigmentos en polvo Easycolor® ,para pinturas, cementos, cales, bellas artes, etc. Fabricados por G&C Colors, S.A.

Recetario tradicional uso Easycolor. Pintura a la cal. Mayo 2012 V.0 Página 4 de 4