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Blue is one of the three primary colours in the RYB colour model, as well as in the RGB (additive) colour model. It lies between violet and cyan on the spectrum of visible light. The eye perceives blue when observing light with a dominant wavelength between approximately 450 and 495 nanometres. Most blues contain a slight mixture of other colours; azure contains some green, while ultramarine contains some violet. The clear daytime sky and the deep sea appear blue because of an optical effect known as Rayleigh scattering. An optical effect called Tyndall effect explains blue eyes. Distant objects appear more blue because of another optical effect called aerial perspective.
Ultramarine is a deep blue color pigment which was originally made by grinding lapis lazuli into a powder. The name comes from the Latin ultramarinus, literally 'beyond the sea', because the pigment was imported into Europe from mines in Afghanistan by Italian traders during the 14th and 15th centuries.
Lazurite is a tectosilicate mineral with sulfate, sulfur and chloride with formula (Na,Ca)8[(S,Cl,SO4,OH)2|(Al6Si6O24)]. It is a feldspathoid and a member of the sodalite group. Lazurite crystallizes in the isometric system although well‐formed crystals are rare. It is usually massive and forms the bulk of the gemstone lapis lazuli.
A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compounds. Pigments of prehistoric and historic value include ochre, charcoal, and lapis lazuli.
Basic copper carbonate is a chemical compound, more properly called copper(II) carbonate hydroxide. It is an ionic compound consisting of the ions copper(II) Cu2+
, carbonate CO2−
3, and hydroxide OH−
.
Malachite is a copper carbonate hydroxide mineral, with the formula Cu2CO3(OH)2. This opaque, green-banded mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses, in fractures and deep, underground spaces, where the water table and hydrothermal fluids provide the means for chemical precipitation. Individual crystals are rare, but occur as slender to acicular prisms. Pseudomorphs after more tabular or blocky azurite crystals also occur.
Azurite is a soft, deep-blue copper mineral produced by weathering of copper ore deposits. During the early 19th century, it was also known as chessylite, after the type locality at Chessy-les-Mines near Lyon, France. The mineral, a basic carbonate with the chemical formula Cu3(CO3)2(OH)2, has been known since ancient times, and was mentioned in Pliny the Elder's Natural History under the Greek name kuanos (κυανός: "deep blue," root of English cyan) and the Latin name caeruleum. Since antiquity, azurite's exceptionally deep and clear blue has been associated with low-humidity desert and winter skies. The modern English name of the mineral reflects this association, since both azurite and azure are derived via Arabic from the Persian lazhward (لاژورد), an area known for its deposits of another deep-blue stone, lapis lazuli ("stone of azure").
Oil paint is a type of slow-drying paint that consists of particles of pigment suspended in a drying oil, commonly linseed oil. The viscosity of the paint may be modified by the addition of a solvent such as turpentine or white spirit, and varnish may be added to increase the glossiness of the dried oil paint film. The addition of oil or alkyd medium can also be used to modify the viscosity and drying time of oil paint. Oil paints were first used in Asia as early as the 7th century AD and can be seen in examples of Buddhist paintings in Afghanistan. Oil-based paints made their way to Europe by the 12th century and were used for simple decoration, but oil painting did not begin to be adopted as an artistic medium there until the early 15th century. Common modern applications of oil paint are in finishing and protection of wood in buildings and exposed metal structures such as ships and bridges. Its hard-wearing properties and luminous colors make it desirable for both interior and exterior use on wood and metal. Due to its slow-drying properties, it has recently been used in paint-on-glass animation. The thickness of the coat has considerable bearing on the time required for drying: thin coats of oil paint dry relatively quickly.
Copper carbonate may refer to :
Verdigris is the common name for blue-green, copper-based pigments that form a patina on copper, bronze, and brass. The technical literature is ambiguous as to its chemical composition. Some sources refer to "neutral verdigris" as copper(II) acetate monohydrate (Cu(CH3CO2)2·(H2O)) and to "blue verdigris" as Cu(CH3CO2)2·CuO·(H2O)6. Another source describes it as a basic copper carbonate (Cu
2CO
3(OH)2), and, when near the sea, basic copper chloride (Cu2(OH)3Cl). Still other sources describe verdigris as Cu(CH3CO2)2.(Cu(OH)2)n where n varies from 0 to 3. The alchemical symbol for verdigris is 🜨 (unicode U+1F728).
Copper(II) hydroxide is the hydroxide of copper with the chemical formula of Cu(OH)2. It is a pale greenish blue or bluish green solid. Some forms of copper(II) hydroxide are sold as "stabilized" copper(II) hydroxide, although they likely consist of a mixture of copper(II) carbonate and hydroxide. Cupric hydroxide is a strong base, although its low solubility in water makes this hard to observe directly.
Lapis armenus, also known as Armenian stone or lapis stellatus, in natural history, is a variety of precious stone, resembling lapis lazuli, except that it is softer, and instead of veins of pyrite, is intermixed with green. "The Armenian stone" is so similar to lapis lazuli that it has often not been distinguished from it; Webster's Revised Unabridged Dictionary for instance treats the two terms as synonyms. The Dictionary of Traded Goods and Commodities 1550-1820 defines lapis armenus as
Armenian stone, or azurite, a naturally occurring basic copper carbonate, originally from Armenia, but later from Germany, from which blue bice was prepared. It was often found in association with another copper carbonate, malachite from which green bice was prepared... Probably because they were both blue, blue bice was sometimes misinterpreted to mean lapis lazuli.
Han purple and Han blue are synthetic barium copper silicate pigments developed in China and used in ancient and imperial China from the Western Zhou period until the end of the Han dynasty.
Egyptian blue, also known as calcium copper silicate (CaCuSi4O10 or CaOCuO(SiO2)4 (calcium copper tetrasilicate)) or cuprorivaite, is a pigment that was used in ancient Egypt for thousands of years. It is considered to be the first synthetic pigment. It was known to the Romans by the name caeruleum. After the Roman era, Egyptian blue fell from use and, thereafter, the manner of its creation was forgotten. In modern times, scientists have been able to analyze its chemistry and reconstruct how to make it.
Stil de grain yellow or sap green is a pigment derived from berries of the buckthorn species Rhamnus saxatilis, which are commonly called Avignon berries or Persian berries after two historical areas of supply; latterly Italy was a major source. The color, whose principal chemical component is rhamnetin, was formerly called pink ; latterly, to distinguish it from light red "pink", the yellow "pink" was qualified as Dutch pink, brown pink, English pink, Italian pink, or French pink — the first three also applied to similar quercitron dyes from the American eastern black oak, Quercus velutina. Other names are Persian berries lake, yellow berries and buckthorn berries.
Chalconatronite is a carbonate mineral and rare secondary copper mineral that contains copper, sodium, carbon, oxygen, and hydrogen, its chemical formula is Na2Cu(CO3)2•3(H2O). Chalconatronite is partially soluble in water, and only decomposes, although chalconatronite is soluble while cold, in dilute acids. The name comes from the mineral's compounds, copper ("chalcos" in Greek) and natron, naturally forming sodium carbonate. The mineral is thought to be formed by water carrying alkali carbonates (possibly from soil) reacting with bronze. Similar minerals include malachite, azurite, and other copper carbonates. Chalconatronite has also been found and recorded in Australia, Germany, and Colorado.
The colour blue has been important in culture, politics, art and fashion since ancient times. Blue was used in ancient Egypt for jewellery and ornament. In the Renaissance, blue pigments were prized for paintings and fine blue and white porcelain. in the Middle Ages, deep rich blues made with cobalt were used in stained glass windows. In the 19th century, the colour was often used for military uniforms and fashion.
Blue pigments are natural or synthetic materials, usually made from minerals and insoluble with water, used to make the blue colors in painting and other arts. The raw material of the earliest blue pigment, lapis lazuli, came from mines in Afghanistan, was refined into the pigment ultramarine. It was widely used for painting in the Middle Ages and Renaissance. Since the late 18th and 19th century, blue pigments are largely synthetic, manufactured in laboratories and factories.
Green pigments are the materials used to create the green colors seen in painting and the other arts. Most come from minerals, particularly those containing compounds of copper. Green pigments reflect the green portions of the spectrum of visible light, and absorb the others. Important green pigments in art history include Malachite and Verdigris, found in tomb paintings in Ancient Egypt, and the Green earth pigments popular in the Middle Ages. More recent greens, such as Cobalt Green, are largely synthetic, made in laboratories and factories.
References
- ↑ One or more of the preceding sentences incorporates text from a publication now in the public domain : Chisholm, Hugh, ed. (1911). "Bice". Encyclopædia Britannica . Vol. 3 (11th ed.). Cambridge University Press. p. 911.
- ↑ HMC 9th Report: Canterbury (London, 1883), p. 150.
- ↑ Roskill & Hand, ed., Hans Holbein, Paintings, Prints, and Reception (Yale, 2001), p. 119.
- ↑ Bristow, Ian C., Interior house-Painting Colours and Technology, 1615-1640 (Yale, 1996), p. 17.
- ↑ Chapter 9 of "The Treasure Seekers" by E.Nesbit
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