A
Lake pigment is a
pigmentA pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
manufactured by precipitating a
dyeA dye can generally be described as a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and may require a mordant to improve the fastness of the dye on the fiber....
with an
inertIn English, to be inert is to be in a state of doing little or nothing.-Chemistry:In chemistry, the term inert is used to describe something that is not chemically active. The noble gases were described as being inert because they did not react with the other elements or themselves...
binder, usually a metallic salt. Manufacturers and suppliers to artists and industry frequently omit the
lake designation in the name. Many lake pigments are
fugitiveFugitive pigments, are non-permanent pigments - pigments that lighten in what is understood, said or defined to be a relatively short time when exposed to light...
because the dyes involved are unstable when exposed to light.
The metallic salt or binder used must be very inert and insoluble in the vehicle, and it must be white or very neutral.
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A
Lake pigment is a
pigmentA pigment is a material that changes the color of reflected or transmitted light as the result of wavelength-selective absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which a material emits light.Many materials selectively absorb...
manufactured by precipitating a
dyeA dye can generally be described as a colored substance that has an affinity to the substrate to which it is being applied. The dye is generally applied in an aqueous solution, and may require a mordant to improve the fastness of the dye on the fiber....
with an
inertIn English, to be inert is to be in a state of doing little or nothing.-Chemistry:In chemistry, the term inert is used to describe something that is not chemically active. The noble gases were described as being inert because they did not react with the other elements or themselves...
binder, usually a metallic salt. Manufacturers and suppliers to artists and industry frequently omit the
lake designation in the name. Many lake pigments are
fugitiveFugitive pigments, are non-permanent pigments - pigments that lighten in what is understood, said or defined to be a relatively short time when exposed to light...
because the dyes involved are unstable when exposed to light.
The metallic salt or binder used must be very inert and insoluble in the vehicle, and it must be white or very neutral. It must have low tinting strength so that the dye itself determines which wavelengths are absorbed and reflected by the resulting precipitate. In ancient times chalk, white clay, and crushed bones were used, being sources of
calcium carbonateCalcium carbonate is a chemical compound with the chemical formula CaCO
3. It is a common substance found in rock in all parts of the world, and is the main component of shells of marine organisms, snails, pearls, and eggshells. Calcium carbonate is the active ingredient in agricultural...
and
calcium phosphateCalcium phosphate is the name given to a family of minerals containing calcium ions together with orthophosphates , metaphosphates or pyrophosphates and occasionally hydrogen or hydroxide ions.It is the principal form of calcium found in bovine milk...
. The salts that are commonly used today include
barium sulfateBarium sulfate is a white crystalline solid with the chemical formula BaSO4. It is insoluble in water and other traditional solvents but is soluble in concentrated sulfuric acid. The mineral barite is composed largely of barium sulfate and is a common ore of barium...
,
calcium sulfateCalcium sulfate is a common laboratory and industrial chemical. In the form of γ-anhydrite , it is used as a desiccant. It is also used as a coagulant in products like tofu. In the natural state, unrefined calcium sulfate is a translucent, crystalline white rock...
,
aluminium hydroxideAluminium hydroxide, Al3, is the most stable form of aluminium in normal conditions. It is found in nature as the mineral gibbsite and its three, much more rare, polymorphs: bayerite, doyleite and nordstrandite...
, and
aluminium oxideAluminium oxide is an amphoteric oxide of aluminium with the chemical formula
23. It is also commonly referred to as alumina, corundum, sapphire, ruby or aloxite in the mining, ceramic and materials science communities. It is produced by the Bayer process from bauxite...
(alumina), all of which can be produced cheaply from inexpensive mineral ores.
Lake pigments have a long history in decoration and the arts. Some have been produced for thousands of years and traded over long distances.
- Indigo Lake
Indigo is the color on the electromagnetic spectrum between about 420 and 450 nm in wavelength, placing it between blue and violet. Although traditionally considered one of seven divisions of the optical spectrum, modern color scientists do not usually recognize indigo as a separate division and...
was originally produced from the leaves of woadWoad is the common name of the flowering plant Isatis tinctoria in the family Brassicaceae. It is commonly called dyer's woad, and sometimes incorrectly listed as Isatis indigotica . It is occasionally known as Asp of Jerusalem. Woad is also the name of a blue dye produced from the plant...
, and was known in ancient EgyptEgypt , officially the Arab Republic of Egypt, is a country mainly in North Africa, with the Sinai Peninsula forming a land bridge in Western Asia...
. In the late Middle Ages, a fashion for woad as a textile dye led to overplanting and soil exhaustion in many parts of Europe. After trade routes opened to the east, Indigo was imported from India as a substitute for woad, and the cultivation of woad became uneconomical in Europe. Today, the dark blue dye once produced from woad is known as Indigo. The dye and pigment are both fugitive.
- Rose Madder Lake
Rose madder, sometimes referred to as Rose Madder Genuine is the crushed root of the Common Madder plant . The ancient Egyptians used rose madder to create pinkish rose-colored textile dyes...
, originally from the root of the madderRubia is a genus of the madder family Rubiaceae, which contains about 60 species of perennial scrambling or climbing herbs and sub-shrubs native to the Old World, Africa, temperate Asia and America...
plant, is also known as Alizarin Crimson in its synthetic form. Since Rose Madder is fugitive when exposed to light, its use has been largely superseded, even in synthetic form, by QuinacridoneQuinacridone is a red powder. It is an organic compound with the molecular formula C
20H
12N
2O
2. It is used as a pigment; analogs bearing this motif are known as quinacridones.-Quinacridones:...
pigments.
- Carmine Lake
Carmine , also called Crimson Lake, Cochineal, Natural Red 4, C.I. 75470, or E120, is a pigment of a bright red color obtained from the carminic acid produced by some scale insects, such as the cochineal and the Polish cochineal, and is used as a general term for a particularly deep red color of...
was originally produced from the cochineal insectThe Cochineal is a scale insect in the suborder Sternorrhyncha, from which the crimson-coloured dye carmine is derived. There are other species in the genus Dactylopius that can be used to produce cochineal extract, but they are extremely difficult to distinguish from D...
, native to Central and South America. Another name is Crimson Lake. When the Spanish conquered the Aztec Empire (1518-1521), they encountered Aztec warriors garbed in an unknown crimson color. Cochineal became their second most valuable export from the New World, after silver, and they zealously guarded the secret of its production for centuries. Carminic acidCarminic acid is a red glucosidal hydroxyanthrapurin that occurs naturally in some scale insects, such as the cochineal and the Polish cochineal. The insects produce the acid as a deterrent to predators. Carminic acid is the colouring agent in carmine. Synonyms are C.I. 75470 and C.I...
, the organic compound which gives carmine its color, was synthesized in 1991.
Indigo and Rose Madder are now produced more cheaply from synthetic sources, although some use of natural products persists, especially among artisans. The food and cosmetics industries have shown renewed interest in cochineal as a source of natural red dye.