- Practical advice
- Natural or artificial pigments
- Natural pigments
- "Artificial" pigments
- Practical tips for using pigments
- The different pigments
Titanium white, ultramarine or cobalt blue, ocher and earth, emerald green... all the evocations of the chromatic richness of pigments. With a certain control of the dosages, they lend themselves to many decorative techniques such as plaster and whitewash, glazes, frescoes, stucco, etc.
Where to find them?
From producers of coloring earths (Le Moulin à Couleurs, Ocher de France, Solargil...), manufacturers of synthetic pigments (Art ÉColor, Leroux...), manufacturers of lime plasters and natural paints ( Auro, Earth Color, EcoHouse, Ecotec, Europ-lab, Socli...), specialized resellers (Natural Ambience, Well-being materials, Laverdure, La Marchande de couleurs, Sennelier...). You can also find pigments on the Internet: domus-construction.fr, eco-logis.com, tresors-de-provence.com, nature-et-habitat.com.
La Marchande de Couleurs publishes and sells by mail a clever little "catalog of recipes for paints and coatings" 5,34 € (35 F). The association Terres et Couleurs also offers in VPC, in the same prices, illustrated notebooks on the use of ocher, land and lime.
To be remembered among the more complete books: "Recettes d'atelier / Techniques picturales anciennes" by Jean-Claude Misset (éd Massin), "Les coatings écoratifs" by Philippe Chastel (Dessain and Tolra editions), and "Paints and finishes" old-fashioned "Annie Sloan and Kate Gwynn (ed Rustic House).
Natural or artificial pigments
Presented in the form of more or less fine colored powders, the pigments are of two types: natural or artificial.
Most are insoluble, which promotes their staining power. For this reason, they are used in fine load such as sand, chalk, marble powder... and must be taken into account during dosages. Natural pigments are non-toxic, miscible with each other and with all binders: lime, casein, egg, oils, resins, waxes, etc.
It is not the same for metal oxides, obtained by chemical reaction, and synthetic pigments: handle with care! In addition, pay attention to some sometimes abusive names, which consist of playing on words. Clearly, some manufacturers tend to pass synthetic pigments as natural, because they do not include heavy metals.
These dyes offer variable performance depending on whether they are of mineral or organic origin (vegetable, animal).
Mineral pigments (ocher and earth) come from natural combinations of clays and metal oxides. The shades obtained can be calcined to accentuate them or obtain shades: light to dark red ocher, Sienna, burnt shade, etc. These pigments are distinguished by a high covering power and good resistance to U.V. and weathering.
Both outdoors and indoors, they express themselves fully in plaster and lime paints. Beyond 25% of land for whitewash, 65% for tempera (fresco) and 85% for a patina, the addition of dye no longer changes the color. From 10% of pigment, it is advisable to adjuvant the milk of lime, to stabilize it, with 5 to 10% of casein, egg, vegetable resin or acrylic.
The family of mineral pigments also includes colored rocks and semi-precious stones finely ground. They give sumptuous hues, among which: azurite or malachite (deep blue and green), hematite (red and brown), lapis lazuli (real clear and transparent ultramarine blue). Their coloring power is very good, except for malachite, but their high price is destined for luxurious decorations.
Pastel blue, carmine, madder, indigo, purple, black fruits or bone cores... are some examples of pigments of plant or animal origin. With the exception of blacks, their resistance in coatings is quite low and their hiding power limited in lime milks. Moreover, their ability to dissolve completely in the binder creates transparent shades, fragile to light. They are reserved for glazes and oil preparations, as well as for light patinas.
Oxides and pigments of synthesis are distinguished by a strong coloring power, with tones more alive than their natural counterparts. But they are sometimes less stable over time. They can be used for oil glazes, egg tempera or stuccoes. However, coming from chemistry, they do not always get along with binders like lime (check their compatibilities).
The color saturation limit of the oxides is 15% limewash, 35% fresco and 50% patina. For synthetic pigments, these dosages are divided by three. Some pigments can not mix with others containing iron or sulfur, or both. Cadmiums (sulfur based) should not be mixed with lead pigments (yellow, chrome orange). Some oxides, chromates and sulphides are also very toxic and should be handled with caution (do not touch or inhale).
Practical tips for using pigments
To obtain pure tones, it is advisable to crush the pigment with the binder (oil, egg, waxes...) on a plate or in a bowl, until obtaining a creamy and lump-free paste. The fineness of the soil allows them to be mixed directly with lime but it is always possible, in coatings as in paints, to incorporate the dye in the form of sieved syrup, consisting of powder of pigments, a drop of liquid soap as "wetting agent" and a little water. Whatever the method, it is advisable to make complete preliminary tests. Many recipes just need to be experimented and improved.
The different pigments
Located in Saint-Amand-en-Puysaye (89), the "Fine Arts" quarry is used for the extraction of clay and ocher. The pigments obtained, presented in powder or crude extraction, are used to tint paints and mortars, or even ceramics and metals for some (yellow ocher, hematite).
The ochres contain iron hydroxide (yellow or red), the shady or Sienna lands of manganese (brown), and the green lands of copper. These are among the oldest colors used.
A majority of commercially available reds, purples and oranges are derived from chemistry. They are here offered in different packages from 25 g to 1 kg, depending on the "qualities".
Whitewash is a highly diluted wash, which can be colored with pigments and adjuvanted to fix it. After application, it is more or less translucent depending on the amount of water used.
For a stucco, colored plaster in the mass, the Siena earth is mixed directly with calcium lime with 2 volumes of pigments for 3 lime. After adding adjuvant and water, the whole is long kneaded with a spatula (here on a glass plate) to obtain a homogeneous paste. The preparation is done the day before.
To tint a decorative coating with lime, it is recommended not to exceed 3% of pigment relative to the weight of the binder. Their coloring and opacifying power is high.
In finishing, this coating is covered with a completely natural vegetable stain, applied in circular and crossed movements with a simple brush to glue.
On a yellowing, uneven, yellow background, a second layer of red stain is applied using a rolled cotton fabric. The effects are infinitely variable.
The fresco is done on a mortar still fresh. To paint the decoration, we exclusively use lime water and pigments.
Natural wax is often associated with decorative coatings. In this case, it is tinted with mineral pigments and polish (to the cloth or brush) to obtain a satin surface, impervious and resistant to soiling.