lime whitewash
Lime whitewash is the simplest and most economical technique of air lime plastering to achieve its finishes and decorations. Due to the recognised disinfectant qualities of lime, we can use it in wet or dry and hot environments, without any problems of mould. It can be applied both outdoors and indoors. Its support of choice is a lime coating, fresh or already dry, because it will become one with it. Lime whitewash is highly appreciated for its matt and velvety aspect, which is typical of lime and allows us infinite possibilities of realisation.
the ingredients we will use for the whitewashes
air lime in powder or paste form: I particularly recommend air lime in artisanal paste form, as its carbonation and plasticity qualities are exceptional, far superior to industrial lime in powder form, which makes it possible to load more and obtain a more solid result.
chalk, or meudon white, which is a non-colouring mineral filler.
talc (magnesium silicate) which gives smoothness and accentuates the softness of the whitewash.
casein powder or prepared casein, which is used as a fixative.
the liquid vinyl binder, which will also serve as a fixative for indoor and outdoor use and for more difficult substrates.
the liquid black soap which is a wetting agent that facilitates emulsification
methylcellulose, which is a water-retaining agent and a glue
Saponified wax for some finishes gives a satin and glossy appearance.
water, which is our thinner: depending on the quantity, we will have a whitewash, a whitewash or a whitewash in material. We can use up to 20 times the volume of lime to achieve a patina.
the necessary tools
a mixer on a drill, a measuring container, small buckets, a scale, large containers for mixing (10L buckets), cloths, brushes made of pig bristles (for fine work) or synthetic for more rustic work (be careful not to use brushes with a steel ferrule, as this would oxidize quickly and could cause rust splashes on your walls), sponges, stainless steel spatulas and cloths.
techniques for applying whitewash
fresco technique: The whitewash is applied to a body of plaster (open support) which has set (it has become quite hard) but is still fresh.
dry technique: on a dry body of plaster (open support) the day before and again on the day of the application, re-wet to saturation and apply the whitewash.
dry technique on a closed support such as an old paint, a prepared plasterboard, insert a fixative in the whitewash and apply without moistening the support or very little with a sponge to facilitate the application.
preparation of the whitewash
In a bucket add a little water with a cap of liquid black soap, then add the lime and stir to obtain a fairly liquid paste. Add the fixative if necessary and the fillers (blanc de meudon, talcum powder) according to the type of whitewash you want. Then come the pigments that you will have previously diluted in a little water and black soap (or even household alcohol at 95° depending on the pigment). Continue mixing by adding water until you obtain the desired consistency (pancake batter, except for milk of lime where you need much more water). And finally carry out a sifting if possible to remove the remaining lumps or small pebbles of lime always more or less present. This is not obligatory but if you want a smooth wall it is better (the small stones fall from the wall with a brush once the whitewash is taken, if you cannot sieve).
I also recommend preparing it the day before, it will be all the more pleasant to apply the next day, the aggregates having been well impregnated with water and not hesitating to prepare the quantity for the whole site, the whitewashes keep very well for several days or even years if they are correctly stored.
During use, remember to stir the whitewash often and regularly to avoid the phenomenon of sedimentation, especially when the pigments used are oxides.
the different lime whitewashes
milk of lime:
1 volume of lime (in paste or powder, preferably in paste form) + pigments in % of the weight of lime according to the desired colour + 1 cap of liquid black soap + 10 volumes of water
A lime milk is preferred to even out surfaces without covering them too much in order to preserve the texture of the different materials or to achieve patinas. You can therefore uniform window frames, give a patina to old plaster or whitewash, or to give relief to new plaster, lighten and give a patina to dark woodwork, etc...
It will be possible to apply several coats, the application is done with a thumb brush or a whitewash brush.
On open surfaces it is necessary to moisten the day before, on closed surfaces do not moisten and add a fixative to the whitewash (vinyl binder).
the simple whitewash:
1 volume of lime (paste or powder, preferably paste) + 2 volumes of water + 1 capful of liquid black soap + pigments according to the desired colour in % in relation to the weight of the lime + casein fixative or vinyl binder according to the application support.
the quantity of water is indicative and shows you a standard texture for this type of whitewash, it will have to be adjusted according to the thickness of whitewash desired. However, do not make it too thick, otherwise you risk cracking and delamination.
This type of whitewash is quite rustic and will be used to refresh a barn or garage or cellar as it is not afraid of humidity and is antiseptic.
On open surfaces, simply dampen and then apply two coats with a large whitewash brush. On closed supports it will be necessary to add a fixative such as a vinyl binder at 10% of the weight of the lime and to apply it without moistening the support.
the improved whitewash:
1 volume of lime (in paste or powder but preferably in paste form) + 10% of the weight of the lime in talcum powder + pigments in % of the weight of the lime according to the shade you want to obtain + casein fixative (2% of the weight of lime or 10% of the weight of prepared casein lime) or vinyl binder at 10% of the weight of the lime + a little liquid black soap to promote emulsion + water until the consistency of a crepe paste is obtained.
The application on different supports, open or closed, is possible, as for the simple whitewash.
with this type of whitewash it is possible to create decorations and obtain different finishes with a minimum of 2 coats :
poached effect on a plain tone
cloudy effect: prepare several whitewashes of different colours, apply them to the wall at random and mix them together in a cool place, then poach them.
marble effect: create a cloud to which we will add light or pronounced marbling with one or more whitewashes of a different colour each with a finer brush and marbling brushes.
the whitewash in matter:
1 volume of lime (in paste or powder but preferably in paste) + 20% of the weight of the lime in blanc de meudon (chalk) + 10% of the weight of the lime in talcum powder + 20% of the weight of the lime in pigments according to the desired colour. It will be possible to put more if you want, but it will then be necessary to reduce the talcum powder and the blanc de meudon by the same amount, in order to obtain 50% filler for 50% lime + water until a thick pancake paste is obtained.
The application on open or closed supports is possible. For closed supports it will be necessary to add a fixative at a rate of 10% of the weight of the lime (prepared casein, vinyl binder, acrylic binder, alum salt).
It is possible to insert a water retainer (methylcellulose) to slow down its drying, as for all other types of whitewash, at a rate of 2% of the total volume, in order to have more time to work on it, especially when you wish to create specific decorations.
With this type of whitewash, the designs will be in relief, on which we can apply superimposed layers of coloured lime milk, which we will wipe or spatulate as the work progresses in order to obtain depth and inlays.
It is applied with a brush on an open support previously dampened or directly on a closed support (using the fixative).
This is the type of whitewash that I recommend for exterior façades because it is the most solid.