Pigment
Encyclopedia
Color
Color or colour is the visual perceptual property corresponding in humans to the categories called red, green, blue and others. Color derives from the spectrum of light interacting in the eye with the spectral sensitivities of the light receptors...
of reflected or transmitted light
Light
Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...
as the result of wavelength
Wavelength
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
-selective absorption. This physical process differs from fluorescence
Fluorescence
Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation of a different wavelength. It is a form of luminescence. In most cases, emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation...
, phosphorescence
Phosphorescence
Phosphorescence is a specific type of photoluminescence related to fluorescence. Unlike fluorescence, a phosphorescent material does not immediately re-emit the radiation it absorbs. The slower time scales of the re-emission are associated with "forbidden" energy state transitions in quantum...
, and other forms of luminescence
Luminescence
Luminescence is emission of light by a substance not resulting from heat; it is thus a form of cold body radiation. It can be caused by chemical reactions, electrical energy, subatomic motions, or stress on a crystal. This distinguishes luminescence from incandescence, which is light emitted by a...
, in which a material emits light.
Many materials selectively absorb certain wavelength
Wavelength
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
s of light. Materials that humans have chosen and developed for use as pigments usually have special properties that make them ideal for coloring other materials. A pigment must have a high tinting strength relative to the materials it colors. It must be stable in solid form at ambient temperatures.
For industrial applications, as well as in the arts, permanence and stability are desirable properties. Pigments that are not permanent are called fugitive
Fugitive pigments
Fugitive pigments are non-permanent pigments that lighten in a relatively short time when exposed to light. Fugitive pigments are present in types of paint, markers, inks etc., which are used for temporary applications...
. Fugitive pigments fade over time, or with exposure to light, while some eventually blacken.
Pigments are used for coloring paint, ink
Ink
Ink is a liquid or paste that contains pigments and/or dyes and is used to color a surface to produce an image, text, or design. Ink is used for drawing and/or writing with a pen, brush, or quill...
, plastic
Plastic
A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...
, fabric, cosmetics
Cosmetics
Cosmetics are substances used to enhance the appearance or odor of the human body. Cosmetics include skin-care creams, lotions, powders, perfumes, lipsticks, fingernail and toe nail polish, eye and facial makeup, towelettes, permanent waves, colored contact lenses, hair colors, hair sprays and...
, food
Food
Food is any substance consumed to provide nutritional support for the body. It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals...
and other materials. Most pigments used in manufacturing
Manufacturing
Manufacturing is the use of machines, tools and labor to produce goods for use or sale. The term may refer to a range of human activity, from handicraft to high tech, but is most commonly applied to industrial production, in which raw materials are transformed into finished goods on a large scale...
and the visual arts
Visual arts
The visual arts are art forms that create works which are primarily visual in nature, such as ceramics, drawing, painting, sculpture, printmaking, design, crafts, and often modern visual arts and architecture...
are dry colourant
Colourant
A colourant or colorant is something added to something else to cause a change in colour. Colourants can be:* Dyes* Pigments* Biological pigments* Inks* Paint* Coloured chemicals...
s, usually ground into a fine powder
Powder (substance)
A powder is a dry,thick bulk solid composed of a large number of very fine particles that may flow freely when shaken or tilted. Powders are a special sub-class of granular materials, although the terms powder and granular are sometimes used to distinguish separate classes of material...
. This powder is added to a vehicle (or binder), a relatively neutral or colorless material that suspends
Suspension (chemistry)
In chemistry, a suspension is a heterogeneous fluid containing solid particles that are sufficiently large for sedimentation. Usually they must be larger than 1 micrometer. The internal phase is dispersed throughout the external phase through mechanical agitation, with the use of certain...
the pigment and gives the paint its adhesion.
The worldwide market for inorganic, organic and special pigments had a total volume of around 7.4 million tons in 2006. Asia has the highest rate on a quantity basis followed by Europe and North America. In 2006, a turnover of 17.6 billion US$ (13 billion euro) was reached mostly in Europe, followed by North America and Asia. The global demand on pigments was roughly US$ 20.5 billion in 2009, around 1.5-2% up from the previous year. It is predicted to increase in a stable growth rate in the coming years. The worldwide sales will increase to US$ 24.5 billion in 2015, and reach US$ 27.5 billion in 2018.
A distinction is usually made between a pigment, which is insoluble in the vehicle (resulting in a suspension), and a dye
Dye
A dye is 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 requires a mordant to improve the fastness of the dye on the fiber....
, which either is itself a liquid
Liquid
Liquid is one of the three classical states of matter . Like a gas, a liquid is able to flow and take the shape of a container. Some liquids resist compression, while others can be compressed. Unlike a gas, a liquid does not disperse to fill every space of a container, and maintains a fairly...
or is soluble in its vehicle (resulting in a solution). The term biological pigment
Biological pigment
Biological pigments, also known simply as pigments or biochromes are substances produced by living organisms that have a color resulting from selective color absorption. Biological pigments include plant pigments and flower pigments...
is used for all colored substances independent of their solubility. A colorant can be both a pigment and a dye depending on the vehicle it is used in. In some cases, a pigment can be manufactured from a dye by precipitating
Precipitation (chemistry)
Precipitation is the formation of a solid in a solution or inside anothersolid during a chemical reaction or by diffusion in a solid. When the reaction occurs in a liquid, the solid formed is called the precipitate, or when compacted by a centrifuge, a pellet. The liquid remaining above the solid...
a soluble dye with a metallic salt. The resulting pigment is called a lake pigment
Lake pigment
A lake pigment is a pigment manufactured by precipitating a dye with an inert binder, usually a metallic salt. The word lake is a homonym of lake as body of water and does not refer to it....
.
Physical basis
Light
Light or visible light is electromagnetic radiation that is visible to the human eye, and is responsible for the sense of sight. Visible light has wavelength in a range from about 380 nanometres to about 740 nm, with a frequency range of about 405 THz to 790 THz...
. White light
White
White is a color, the perception of which is evoked by light that stimulates all three types of color sensitive cone cells in the human eye in nearly equal amounts and with high brightness compared to the surroundings. A white visual stimulation will be void of hue and grayness.White light can be...
is a roughly equal mixture of the entire spectrum of visible light with a wavelength
Wavelength
In physics, the wavelength of a sinusoidal wave is the spatial period of the wave—the distance over which the wave's shape repeats.It is usually determined by considering the distance between consecutive corresponding points of the same phase, such as crests, troughs, or zero crossings, and is a...
in a range from about 380 or 400 nanometre
Nanometre
A nanometre is a unit of length in the metric system, equal to one billionth of a metre. The name combines the SI prefix nano- with the parent unit name metre .The nanometre is often used to express dimensions on the atomic scale: the diameter...
s to about 760 or 780 nm. When this light encounters a pigment, parts of the spectrum are absorbed
Absorption (electromagnetic radiation)
In physics, absorption of electromagnetic radiation is the way by which the energy of a photon is taken up by matter, typically the electrons of an atom. Thus, the electromagnetic energy is transformed to other forms of energy for example, to heat. The absorption of light during wave propagation is...
by the chemical bond
Chemical bond
A chemical bond is an attraction between atoms that allows the formation of chemical substances that contain two or more atoms. The bond is caused by the electromagnetic force attraction between opposite charges, either between electrons and nuclei, or as the result of a dipole attraction...
s of conjugated systems and other components of the pigment. Some other wavelengths or parts of the spectrum are reflected or scattered. Most pigments are charge-transfer complexes, like transition metal compounds, with broad absorption band
Absorption band
An absorption band is a range of wavelengths, frequencies or energies in the electromagnetic spectrum which are able to excite a particular transition in a substance...
s that subtract most of the colors of the incident white light. The new reflected light spectrum creates the appearance of a color
Color
Color or colour is the visual perceptual property corresponding in humans to the categories called red, green, blue and others. Color derives from the spectrum of light interacting in the eye with the spectral sensitivities of the light receptors...
. Ultramarine
Ultramarine
Ultramarine is a blue pigment consisting primarily of a double silicate of aluminium and sodium with some sulfides or sulfates, and occurring in nature as a proximate component of lapis lazuli...
reflects blue light, and absorbs other colors. Pigments, unlike fluorescent
Fluorescence
Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation of a different wavelength. It is a form of luminescence. In most cases, emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation...
or phosphorescent
Phosphorescence
Phosphorescence is a specific type of photoluminescence related to fluorescence. Unlike fluorescence, a phosphorescent material does not immediately re-emit the radiation it absorbs. The slower time scales of the re-emission are associated with "forbidden" energy state transitions in quantum...
substances, can only subtract
Subtractive color
A subtractive color model explains the mixing of paints, dyes, inks, and natural colorants to create a full range of colors, each caused by subtracting some wavelengths of light and reflecting the others...
wavelengths from the source light, never add new ones.
So a BLUE PIGMENT is BLUE because it doesn't reflect RED and GREEN light, or because it reflects all colors but the complementary of the BLUE one, which is ORANGE
A PURPLE PIGMENT is PURPLE because it absorbs all GREEN light.
The appearance of pigments is intimately connected to the color of the source light. Sunlight has a high color temperature
Color temperature
Color temperature is a characteristic of visible light that has important applications in lighting, photography, videography, publishing, manufacturing, astrophysics, and other fields. The color temperature of a light source is the temperature of an ideal black-body radiator that radiates light of...
, and a fairly uniform spectrum, and is considered a standard for white light. Artificial light sources tend to have great peaks in some parts of their spectrum, and deep valleys in others. Viewed under these conditions, pigments will appear different colors.
Color spaces used to represent colors numerically must specify their light source. Lab color
Lab color space
A Lab color space is a color-opponent space with dimension L for lightness and a and b for the color-opponent dimensions, based on nonlinearly compressed CIE XYZ color space coordinates....
measurements, unless otherwise noted, assume that the measurement was taken under a D65 light source, or "Daylight 6500 K", which is roughly the color temperature
Color temperature
Color temperature is a characteristic of visible light that has important applications in lighting, photography, videography, publishing, manufacturing, astrophysics, and other fields. The color temperature of a light source is the temperature of an ideal black-body radiator that radiates light of...
of sunlight.
Other properties of a color, such as its saturation or lightness, may be determined by the other substances that accompany pigments. Binders and fillers added to pure pigment chemicals also have their own reflection and absorption patterns, which can affect the final spectrum. Likewise, in pigment/binder mixtures, individual rays of light may not encounter pigment molecules, and may be reflected as is. These stray rays of source light contribute to the saturation of the color. Pure pigment allows very little white light to escape, producing a highly saturated color. A small quantity of pigment mixed with a lot of white binder, however, will appear desaturated and pale, due to the high quantity of escaping white light.
History
Naturally occurring pigments such as ochreOchre
Ochre is the term for both a golden-yellow or light yellow brown color and for a form of earth pigment which produces the color. The pigment can also be used to create a reddish tint known as "red ochre". The more rarely used terms "purple ochre" and "brown ochre" also exist for variant hues...
s and iron oxide
Iron oxide
Iron oxides are chemical compounds composed of iron and oxygen. All together, there are sixteen known iron oxides and oxyhydroxides.Iron oxides and oxide-hydroxides are widespread in nature, play an important role in many geological and biological processes, and are widely utilized by humans, e.g.,...
s have been used as colorants since prehistoric times. Archaeologists have uncovered evidence that early humans used paint
Paint
Paint is any liquid, liquefiable, or mastic composition which after application to a substrate in a thin layer is converted to an opaque solid film. One may also consider the digital mimicry thereof...
for aesthetic purposes such as body decoration. Pigments and paint grinding equipment believed to be between 350,000 and 400,000 years old have been reported in a cave
Cave
A cave or cavern is a natural underground space large enough for a human to enter. The term applies to natural cavities some part of which is in total darkness. The word cave also includes smaller spaces like rock shelters, sea caves, and grottos.Speleology is the science of exploration and study...
at Twin Rivers, near Lusaka, Zambia
Zambia
Zambia , officially the Republic of Zambia, is a landlocked country in Southern Africa. The neighbouring countries are the Democratic Republic of the Congo to the north, Tanzania to the north-east, Malawi to the east, Mozambique, Zimbabwe, Botswana and Namibia to the south, and Angola to the west....
.
Before the Industrial Revolution
Industrial Revolution
The Industrial Revolution was a period from the 18th to the 19th century where major changes in agriculture, manufacturing, mining, transportation, and technology had a profound effect on the social, economic and cultural conditions of the times...
, the range of color available for art and decorative uses was technically limited. Most of the pigments in use were earth and mineral
Mineral
A mineral is a naturally occurring solid chemical substance formed through biogeochemical processes, having characteristic chemical composition, highly ordered atomic structure, and specific physical properties. By comparison, a rock is an aggregate of minerals and/or mineraloids and does not...
pigments, or pigments of biological origin. Pigments from unusual sources such as botanical materials, animal waste, insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
s, and mollusks were harvested and traded over long distances. Some colors were costly or impossible to mix with the range of pigments that were available. Blue
Blue
Blue is a colour, the perception of which is evoked by light having a spectrum dominated by energy with a wavelength of roughly 440–490 nm. It is considered one of the additive primary colours. On the HSV Colour Wheel, the complement of blue is yellow; that is, a colour corresponding to an equal...
and purple
Purple
Purple is a range of hues of color occurring between red and blue, and is classified as a secondary color as the colors are required to create the shade....
came to be associated with royalty
Royal family
A royal family is the extended family of a king or queen regnant. The term imperial family appropriately describes the extended family of an emperor or empress, while the terms "ducal family", "grand ducal family" or "princely family" are more appropriate to describe the relatives of a reigning...
because of their expense.
Biological pigments were often difficult to acquire, and the details of their production were kept secret by the manufacturers. Tyrian Purple
Tyrian purple
Tyrian purple , also known as royal purple, imperial purple or imperial dye, is a purple-red natural dye, which is extracted from sea snails, and which was possibly first produced by the ancient Phoenicians...
is a pigment made from the mucus
Mucus
In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. Mucous fluid is typically produced from mucous cells found in mucous glands. Mucous cells secrete products that are rich in glycoproteins and water. Mucous fluid may also originate from mixed glands, which...
of one of several species of Murex snail
Hexaplex trunculus
Hexaplex trunculus is a medium-sized species of sea snail, a marine gastropod mollusk in the family Muricidae, the murex shells or rock snails....
. Production of Tyrian Purple for use as a fabric
Fabric
A fabric is a textile material, short for "textile fabric".Fabric may also refer to:*Fabric , the spatial and geometric configuration of elements within a rock*Fabric , a nightclub in London, England...
dye began as early as 1200 BCE by the Phoenicia
Phoenicia
Phoenicia , was an ancient civilization in Canaan which covered most of the western, coastal part of the Fertile Crescent. Several major Phoenician cities were built on the coastline of the Mediterranean. It was an enterprising maritime trading culture that spread across the Mediterranean from 1550...
ns, and was continued by the Greeks
Greeks
The Greeks, also known as the Hellenes , are a nation and ethnic group native to Greece, Cyprus and neighboring regions. They also form a significant diaspora, with Greek communities established around the world....
and Romans
Byzantine Empire
The Byzantine Empire was the Eastern Roman Empire during the periods of Late Antiquity and the Middle Ages, centred on the capital of Constantinople. Known simply as the Roman Empire or Romania to its inhabitants and neighbours, the Empire was the direct continuation of the Ancient Roman State...
until 1453 CE, with the fall of Constantinople. The pigment was expensive and complex to produce, and items colored with it became associated with power and wealth. Greek historian Theopompus
Theopompus
Theopompus was a Greek historian and rhetorician- Biography :Theopompus was born on Chios. In early youth he seems to have spent some time at Athens, along with his father, who had been exiled on account of his Laconian sympathies...
, writing in the 4th century BCE, reported that "purple for dyes fetched its weight in silver
Silver
Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...
at Colophon
Colophon
Colophon was a city in the region of Lydia in antiquity dating from about the turn of the first millennium-BC. It was likely one the oldest of the twelve Ionian League cities, between Lebedos and Ephesus and its ruins are in the eponymously named modern region of Ionia.The city's name comes from...
[in Asia Minor]."
Mineral pigments were also traded over long distances. The only way to achieve a deep rich blue was by using a semi-precious stone, lapis lazuli
Lapis lazuli
Lapis lazuli is a relatively rare semi-precious stone that has been prized since antiquity for its intense blue color....
, to produce a pigment known as ultramarine
Ultramarine
Ultramarine is a blue pigment consisting primarily of a double silicate of aluminium and sodium with some sulfides or sulfates, and occurring in nature as a proximate component of lapis lazuli...
, and the best sources of lapis were remote. Flemish painter Jan Van Eyck
Jan van Eyck
Jan van Eyck was a Flemish painter active in Bruges and considered one of the best Northern European painters of the 15th century....
, working in the 15th century, did not ordinarily include blue in his paintings. To have one's portrait commissioned and painted with ultramarine blue was considered a great luxury. If a patron wanted blue, they were forced to pay extra. When Van Eyck used lapis, he never blended it with other colors. Instead he applied it in pure form, almost as a decorative glaze. The prohibitive price of lapis lazuli
Lapis lazuli
Lapis lazuli is a relatively rare semi-precious stone that has been prized since antiquity for its intense blue color....
forced artists to seek less expensive replacement pigments, both mineral (azurite
Azurite
Azurite is a soft, deep blue copper mineral produced by weathering of copper ore deposits. It is also known as Chessylite after the type locality at Chessy-les-Mines near Lyon, France...
, smalt
Smalt
Smalt is powdered glass, colored to a deep powder blue hue using cobalt ions derived from cobalt oxide . Smalt is used as a pigment in painting, and for surface decoration of other types of glass and ceramics, and other media...
) and biological (indigo
Indigo dye
Indigo dye is an organic compound with a distinctive blue color . Historically, indigo was a natural dye extracted from plants, and this process was important economically because blue dyes were once rare. Nearly all indigo dye produced today — several thousand tons each year — is synthetic...
).
Carmine
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 aluminum salt of carminic acid, which is produced by some scale insects, such as the cochineal beetle and the Polish cochineal, and is used as a general term for...
, a dye and pigment derived from a parasitic insect found in Central
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
and South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...
, attained great status and value in Europe. Produced from harvested, dried, and crushed cochineal insects
Cochineal
The cochineal is a scale insect in the suborder Sternorrhyncha, from which the crimson-colour dye carmine is derived. A primarily sessile parasite native to tropical and subtropical South America and Mexico, this insect lives on cacti from the genus Opuntia, feeding on plant moisture and...
, carmine could be, and still is, used in fabric dye, food dye, body paint, or in its solid lake
Lake pigment
A lake pigment is a pigment manufactured by precipitating a dye with an inert binder, usually a metallic salt. The word lake is a homonym of lake as body of water and does not refer to it....
form, almost any kind of paint or cosmetic
Cosmetics
Cosmetics are substances used to enhance the appearance or odor of the human body. Cosmetics include skin-care creams, lotions, powders, perfumes, lipsticks, fingernail and toe nail polish, eye and facial makeup, towelettes, permanent waves, colored contact lenses, hair colors, hair sprays and...
.
Natives of Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....
had been producing cochineal dyes for textiles since at least 700 CE, but Europeans had never seen the color before. When the Spanish invaded the Aztec empire in what is now Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
, they were quick to exploit the color for new trade opportunities. Carmine
Carmine
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 aluminum salt of carminic acid, which is produced by some scale insects, such as the cochineal beetle and the Polish cochineal, and is used as a general term for...
became the region's second most valuable export next to silver. Pigments produced from the cochineal insect gave the Catholic cardinals
Cardinal (Catholicism)
A cardinal is a senior ecclesiastical official, usually an ordained bishop, and ecclesiastical prince of the Catholic Church. They are collectively known as the College of Cardinals, which as a body elects a new pope. The duties of the cardinals include attending the meetings of the College and...
their vibrant robes and the English "Redcoats" their distinctive uniforms. The true source of the pigment, an insect, was kept secret until the 18th century, when biologists discovered the source.
Johannes Vermeer
Johannes, Jan or Johan Vermeer was a Dutch painter who specialized in exquisite, domestic interior scenes of middle class life. Vermeer was a moderately successful provincial genre painter in his lifetime...
often made lavish use of lapis lazuli
Lapis lazuli
Lapis lazuli is a relatively rare semi-precious stone that has been prized since antiquity for its intense blue color....
, along with Carmine and Indian yellow
Indian Yellow
Indian yellow, also called euxanthin or euxanthine, is a xanthonoid. It is transparent yellow pigment used in oil paint. Chemically it is a magnesium euxanthate, the magnesium salt of euxanthic acid. It is a clear, deep and luminescent yellow pigment...
, in his vibrant paintings.
Development of synthetic pigments
The earliest known pigments were natural minerals. Natural iron oxides give a range of colors and are found in many PaleolithicPaleolithic
The Paleolithic Age, Era or Period, is a prehistoric period of human history distinguished by the development of the most primitive stone tools discovered , and covers roughly 99% of human technological prehistory...
and Neolithic
Neolithic
The Neolithic Age, Era, or Period, or New Stone Age, was a period in the development of human technology, beginning about 9500 BC in some parts of the Middle East, and later in other parts of the world. It is traditionally considered as the last part of the Stone Age...
cave paintings. Two examples include Red Ochre, anhydrous Fe2O3, and the hydrated Yellow Ochre (Fe2O3.H2O). Charcoal, or carbon black, has also been used as a black pigment since prehistoric times.
Two of the first synthetic pigments were white lead (basic lead carbonate, (PbCO3)2Pb(OH)2) and blue frit (Egyptian Blue
Egyptian Blue
Egyptian blue is chemically known as calcium copper silicate . It is a pigment used by Egyptians for thousands of years. It is considered to be the first synthetic pigment. The pigment was known to the Romans by the name caeruleum...
). White lead is made by combining lead with vinegar (acetic acid
Acetic acid
Acetic acid is an organic compound with the chemical formula CH3CO2H . It is a colourless liquid that when undiluted is also called glacial acetic acid. Acetic acid is the main component of vinegar , and has a distinctive sour taste and pungent smell...
, CH3COOH) in the presence of CO2. Blue frit is calcium copper silicate and was made from glass colored with a copper ore, such as malachite
Malachite
Malachite is a copper carbonate mineral, with the formula Cu2CO32. This green-colored mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses. Individual crystals are rare but do occur as slender to acicular prisms...
. These pigments were used as early as the second millennium BCE
The Industrial
Industrial Revolution
The Industrial Revolution was a period from the 18th to the 19th century where major changes in agriculture, manufacturing, mining, transportation, and technology had a profound effect on the social, economic and cultural conditions of the times...
and Scientific Revolution
Scientific revolution
The Scientific Revolution is an era associated primarily with the 16th and 17th centuries during which new ideas and knowledge in physics, astronomy, biology, medicine and chemistry transformed medieval and ancient views of nature and laid the foundations for modern science...
s brought a huge expansion in the range of synthetic pigments, pigments that are manufactured or refined from naturally occurring materials, available both for manufacturing and artistic expression. Because of the expense of Lapis Lazuli
Lapis lazuli
Lapis lazuli is a relatively rare semi-precious stone that has been prized since antiquity for its intense blue color....
, much effort went into finding a less costly blue pigment.
Prussian Blue
Prussian blue
Prussian blue is a dark blue pigment with the idealized formula Fe718. Another name for the color Prussian blue is Berlin blue or, in painting, Parisian blue. Turnbull's blue is the same substance but is made from different reagents....
was the first modern synthetic pigment, discovered by accident in 1704. By the early 19th century, synthetic and metallic blue pigments had been added to the range of blues, including French ultramarine
Ultramarine
Ultramarine is a blue pigment consisting primarily of a double silicate of aluminium and sodium with some sulfides or sulfates, and occurring in nature as a proximate component of lapis lazuli...
, a synthetic form of lapis lazuli
Lapis lazuli
Lapis lazuli is a relatively rare semi-precious stone that has been prized since antiquity for its intense blue color....
, and the various forms of Cobalt
Cobalt blue
Cobalt blue is a cool, slightly desaturated blue color, historically made using cobalt salts of alumina. It is used in certain ceramics and painting; the different cobalt pigment smalt, based on silica, is more often used directly in tinted transparent glasses...
and Cerulean Blue. In the early 20th century, organic chemistry added Phthalo Blue
Phthalocyanine Blue BN
Phthalocyanine Blue BN, also called monastral blue, phthalo blue , is a bright, greenish-blue crystalline synthetic blue pigment from the group of phthalocyanine dyes....
, a synthetic, organometallic
Organometallic chemistry
Organometallic chemistry is the study of chemical compounds containing bonds between carbon and a metal. Since many compounds without such bonds are chemically similar, an alternative may be compounds containing metal-element bonds of a largely covalent character...
pigment with overwhelming tinting power.
Discoveries in color science created new industries and drove changes in fashion
Fashion
Fashion, a general term for a currently popular style or practice, especially in clothing, foot wear, or accessories. Fashion references to anything that is the current trend in look and dress up of a person...
and taste. The discovery in 1856 of mauveine
Mauveine
Mauveine, also known as aniline purple and Perkin's mauve, was the first synthetic organic chemical dye.Its chemical name is3-amino-2,±9-dimethyl-5-phenyl-7-phenazinium acetate...
, the first aniline dye, was a forerunner for the development of hundreds of synthetic dyes and pigments like azo
Azo compound
Azo compounds are compounds bearing the functional group R-N=N-R', in which R and R' can be either aryl or alkyl. IUPAC defines azo compounds as: "Derivatives of diazene , HN=NH, wherein both hydrogens are substituted by hydrocarbyl groups, e.g. PhN=NPh azobenzene or diphenyldiazene." The more...
and diazo
Diazo
Diazo refers to a type of organic compound called diazo compound that has two linked nitrogen atoms as a terminal functional group. The general formula is R2C=N2. The simplest example of a diazo compound is diazomethane...
compounds which are the source of wide spectrum of colors. Mauveine was discovered by an 18-year-old chemist named William Henry Perkin, who went on to exploit his discovery in industry and become wealthy. His success attracted a generation of followers, as young scientists went into organic chemistry
Organic chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, composition, reactions, and preparation of carbon-based compounds, hydrocarbons, and their derivatives...
to pursue riches. Within a few years, chemists had synthesized a substitute for madder
Madder
Rubia 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...
in the production of Alizarin Crimson
Alizarin
Alizarin or 1,2-dihydroxyanthraquinone is an organic compound with formula that has been used throughout history as a prominent dye, originally derived from the roots of plants of the madder genus.Alizarin was used as a red dye for the English parliamentary "new model" army...
. By the closing decades of the 19th century, textile
Textile
A textile or cloth is a flexible woven material consisting of a network of natural or artificial fibres often referred to as thread or yarn. Yarn is produced by spinning raw fibres of wool, flax, cotton, or other material to produce long strands...
s, paints, and other commodities in colors such as red
Red
Red is any of a number of similar colors evoked by light consisting predominantly of the longest wavelengths of light discernible by the human eye, in the wavelength range of roughly 630–740 nm. Longer wavelengths than this are called infrared , and cannot be seen by the naked eye...
, crimson
Crimson
Crimson is a strong, bright, deep red color. It is originally the color of the dye produced from a scale insect, Kermes vermilio, but the name is now also used as a generic term for those slightly bluish-red colors that are between red and rose; besides crimson itself, these colors include...
, blue, and purple had become affordable.
Development of chemical pigments and dyes helped bring new industrial prosperity to Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
and other countries in northern Europe, but it brought dissolution and decline elsewhere. In Spain's former New World empire, the production of cochineal colors employed thousands of low-paid workers. The Spanish monopoly on cochineal production had been worth a fortune until the early 19th century, when the Mexican War of Independence
Mexican War of Independence
The Mexican War of Independence was an armed conflict between the people of Mexico and the Spanish colonial authorities which started on 16 September 1810. The movement, which became known as the Mexican War of Independence, was led by Mexican-born Spaniards, Mestizos and Amerindians who sought...
and other market changes disrupted production. Organic chemistry
Organic chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, composition, reactions, and preparation of carbon-based compounds, hydrocarbons, and their derivatives...
delivered the final blow for the cochineal color industry. When chemists created inexpensive substitutes for carmine, an industry and a way of life went into steep decline.
New sources for historic pigments
Industrial Revolution
The Industrial Revolution was a period from the 18th to the 19th century where major changes in agriculture, manufacturing, mining, transportation, and technology had a profound effect on the social, economic and cultural conditions of the times...
, many pigments were known by the location where they were produced. Pigments based on minerals and clays often bore the name of the city or region where they were mined. Raw Sienna
Sienna
Sienna is a form of limonite clay most famous in the production of oil paint pigments. Its yellow-brown colour comes from ferric oxides contained within...
and Burnt Sienna came from Siena
Siena
Siena is a city in Tuscany, Italy. It is the capital of the province of Siena.The historic centre of Siena has been declared by UNESCO a World Heritage Site. It is one of the nation's most visited tourist attractions, with over 163,000 international arrivals in 2008...
, Italy
Italy
Italy , officially the Italian Republic languages]] under the European Charter for Regional or Minority Languages. In each of these, Italy's official name is as follows:;;;;;;;;), is a unitary parliamentary republic in South-Central Europe. To the north it borders France, Switzerland, Austria and...
, while Raw Umber and Burnt Umber came from Umbria
Umbria
Umbria is a region of modern central Italy. It is one of the smallest Italian regions and the only peninsular region that is landlocked.Its capital is Perugia.Assisi and Norcia are historical towns associated with St. Francis of Assisi, and St...
. These pigments were among the easiest to synthesize, and chemists created modern colors based on the originals that were more consistent than colors mined from the original ore bodies. But the place names remained.
Historically and culturally, many famous natural pigments have been replaced with synthetic pigments, while retaining historic names. In some cases the original color name has shifted in meaning, as a historic name has been applied to a popular modern color. By convention, a contemporary mixture of pigments that replaces a historical pigment is indicated by calling the resulting color a hue, but manufacturers are not always careful in maintaining this distinction. The following examples illustrate the shifting nature of historic pigment names:
- Indian YellowIndian YellowIndian yellow, also called euxanthin or euxanthine, is a xanthonoid. It is transparent yellow pigment used in oil paint. Chemically it is a magnesium euxanthate, the magnesium salt of euxanthic acid. It is a clear, deep and luminescent yellow pigment...
was once produced by collecting the urine of cattle that had been fed only mangoMangoThe mango is a fleshy stone fruit belonging to the genus Mangifera, consisting of numerous tropical fruiting trees in the flowering plant family Anacardiaceae. The mango is native to India from where it spread all over the world. It is also the most cultivated fruit of the tropical world. While...
leaves. Dutch and Flemish painters of the 17th and 18th centuries favored it for its luminescent qualities, and often used it to represent sunlightSunlightSunlight, in the broad sense, is the total frequency spectrum of electromagnetic radiation given off by the Sun. On Earth, sunlight is filtered through the Earth's atmosphere, and solar radiation is obvious as daylight when the Sun is above the horizon.When the direct solar radiation is not blocked...
. In the novel Girl with a Pearl EarringGirl with a Pearl Earring (novel)Girl with a Pearl Earring is a 1999 historical novel written by Tracy Chevalier. Set in 17th century Delft, Holland, the novel was inspired by Delft school painter Johannes Vermeer's painting Girl with a Pearl Earring. Chevalier presents a fictional account of Vermeer, the model, and the painting...
, Vermeer's patron remarks that Vermeer used "cow piss" to paint his wife. Since mango leaves are nutritionally inadequate for cattle, the practice of harvesting Indian Yellow was eventually declared to be inhumane. Modern hues of Indian Yellow are made from synthetic pigments. - UltramarineUltramarineUltramarine is a blue pigment consisting primarily of a double silicate of aluminium and sodium with some sulfides or sulfates, and occurring in nature as a proximate component of lapis lazuli...
, originally the semi-precious stone lapis lazuliLapis lazuliLapis lazuli is a relatively rare semi-precious stone that has been prized since antiquity for its intense blue color....
, has been replaced by an inexpensive modern synthetic pigment, French Ultramarine, manufactured from aluminium silicateAluminium silicateAluminium silicate has the chemical formula 2SiO3. It has a density of 2.8 to 2.9 g/cm³, a vitreous lustre, a refractive index of 1.56, a Mohs hardness of 4.5-7.5 , and can have orthorhombic crystallography...
with sulfurSulfurSulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...
impurities. At the same time, Royal BlueRoyal blueRoyal blue describes both a bright shade and a dark shade of azure blue. It is said to have been invented by millers in Rode, Somerset, a consortium of which won a competition to make a dress for the British queen, Charlotte of Mecklenburg-Strelitz....
, another name once given to tints produced from lapis lazuli, has evolved to signify a much lighter and brighter color, and is usually mixed from Phthalo Blue and titanium dioxideTitanium dioxideTitanium dioxide, also known as titanium oxide or titania, is the naturally occurring oxide of titanium, chemical formula . When used as a pigment, it is called titanium white, Pigment White 6, or CI 77891. Generally it comes in two different forms, rutile and anatase. It has a wide range of...
, or from inexpensive synthetic blue dyes. Since synthetic ultramarine is chemically identical with lapis lazuli, the "hue" designation is not used. French Blue, yet another historic name for ultramarine, was adopted by the textile and apparel industry as a color name in the 1990s, and was applied to a shade of blue that has nothing in common with the historic pigment ultramarine. - VermilionVermilionVermilion is an opaque orangish red pigment, similar to scarlet. As a naturally occurring mineral pigment, it is known as cinnabar, and was in use around the world before the Common Era began. Most naturally produced vermilion comes from cinnabar mined in China, and vermilion is nowadays commonly...
, a toxic mercuryMercury (element)Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...
compound favored for its deep red-orange color by old master painters such as TitianTitianTiziano Vecelli or Tiziano Vecellio Tiziano Vecelli or Tiziano Vecellio Tiziano Vecelli or Tiziano Vecellio (c. 1488/1490 – 27 August 1576 better known as Titian was an Italian painter, the most important member of the 16th-century Venetian school. He was born in Pieve di Cadore, near...
, has been replaced in painters' palettes by various modern pigments, including cadmium reds. Although genuine Vermilion paint can still be purchased for fine arts and art conservation applications, few manufacturers make it, because of legal liability issues. Few artists buy it, because it has been superseded by modern pigments that are both less expensive and less toxic, as well as less reactive with other pigments. As a result, genuine Vermilion is almost unavailable. Modern vermilion colors are properly designated as Vermilion Hue to distinguish them from genuine Vermilion.
Manufacturing and industrial standards
First published in 1905, the Munsell Color System
Munsell color system
In colorimetry, the Munsell color system is a color space that specifies colors based on three color dimensions: hue, value , and chroma . It was created by Professor Albert H...
became the foundation for a series of color models, providing objective methods for the measurement of color. The Munsell system describes a color in three dimensions, hue
Hue
Hue is one of the main properties of a color, defined technically , as "the degree to which a stimulus can be describedas similar to or different from stimuli that are described as red, green, blue, and yellow,"...
, value
Lightness
Lightness is a philosophical concept most closely associated with continental philosophy and existentialism, which is used in ontology. The term "lightness" varies in usage but is differentiated from physical weight, such as "the lightness of balsa wood"...
(lightness), and chroma (color purity), where chroma is the difference from gray at a given hue and value.
By the middle years of the 20th century, standardized methods for pigment chemistry were available, part of an international movement to create such standards in industry. The International Organization for Standardization
International Organization for Standardization
The International Organization for Standardization , widely known as ISO, is an international standard-setting body composed of representatives from various national standards organizations. Founded on February 23, 1947, the organization promulgates worldwide proprietary, industrial and commercial...
(ISO) develops technical standards for the manufacture of pigments and dyes. ISO standards define various industrial and chemical properties, and how to test for them. The principal ISO standards that relate to all pigments are as follows:
- ISO-787 General methods of test for pigments and extenders.
- ISO-8780 Methods of dispersion for assessment of dispersion characteristics.
Other ISO standards pertain to particular classes or categories of pigments, based on their chemical composition, such as ultramarine
Ultramarine
Ultramarine is a blue pigment consisting primarily of a double silicate of aluminium and sodium with some sulfides or sulfates, and occurring in nature as a proximate component of lapis lazuli...
pigments, titanium dioxide
Titanium dioxide
Titanium dioxide, also known as titanium oxide or titania, is the naturally occurring oxide of titanium, chemical formula . When used as a pigment, it is called titanium white, Pigment White 6, or CI 77891. Generally it comes in two different forms, rutile and anatase. It has a wide range of...
, iron oxide pigments, and so forth.
Many manufacturers of paints, inks, textiles, plastics, and colors have voluntarily adopted the Colour Index International
Colour Index International
Colour Index International is a reference database jointly maintained by the Society of Dyers and Colourists and the American Association of Textile Chemists and Colorists. It was first printed in 1925 but is now published exclusively on the web...
(CII) as a standard for identifying the pigments that they use in manufacturing particular colors. First published in 1925, and now published jointly on the web by the Society of Dyers and Colourists
Society of Dyers and Colourists
The Society of Dyers and Colourists is an international professional society, with headquarters in Bradford, United Kingdom, specializing in colour in all its manifestations. Founded in 1884, it was granted a Royal Charter of Incorporation in 1963...
(United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
) and the American Association of Textile Chemists and Colorists
American Association of Textile Chemists and Colorists
The American Association of Textile Chemists and Colorists is a not-for-profit association that provides test method development, quality control materials, and professional networking for textile professionals throughout the world.-Activities:...
(USA), this index is recognized internationally as the authoritative reference on colorants. It encompasses more than 27,000 products under more than 13,000 generic color index names.
In the CII schema, each pigment has a generic index number that identifies it chemically, regardless of proprietary and historic names. For example, Phthalo Blue has been known by a variety of generic and proprietary names since its discovery in the 1930s. In much of Europe, phthalocyanine blue is better known as Helio Blue, or by a proprietary name such as Winsor Blue. An American paint manufacturer, Grumbacher, registered an alternate spelling (Thalo Blue) as a trademark. Colour Index International
Colour Index International
Colour Index International is a reference database jointly maintained by the Society of Dyers and Colourists and the American Association of Textile Chemists and Colorists. It was first printed in 1925 but is now published exclusively on the web...
resolves all these conflicting historic, generic, and proprietary names so that manufacturers and consumers can identify the pigment (or dye) used in a particular color product. In the CII, all Phthalo Blue pigments are designated by a generic colour index number as either PB15 or PB16, short for pigment blue 15 and pigment blue 16. (The two forms of Phthalo Blue, PB15 and PB16, reflect slight variations in molecular structure that produce a slightly more greenish or reddish blue.)
Scientific and technical issues
Selection of a pigment for a particular application is determined by cost, and by the physical properties and attributes of the pigment itself. For example, a pigment that is used to color glass must have very high heat stability in order to survive the manufacturing process; but, suspended in the glass vehicle, its resistance to alkaliAlkali
In chemistry, an alkali is a basic, ionic salt of an alkali metal or alkaline earth metal element. Some authors also define an alkali as a base that dissolves in water. A solution of a soluble base has a pH greater than 7. The adjective alkaline is commonly used in English as a synonym for base,...
or acidic materials is not an issue. In artistic paint, heat stability is less important, while lightfastness and toxicity
Toxicity
Toxicity is the degree to which a substance can damage a living or non-living organisms. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell or an organ , such as the liver...
are greater concerns.
The following are some of the attributes of pigments that determine their suitability for particular manufacturing processes and applications:
- Lightfastness and sensitivity for damage from ultra violet light
- Heat stability
- ToxicityToxicityToxicity is the degree to which a substance can damage a living or non-living organisms. Toxicity can refer to the effect on a whole organism, such as an animal, bacterium, or plant, as well as the effect on a substructure of the organism, such as a cell or an organ , such as the liver...
- Tinting strength
- Staining
- DispersionDispersion (chemistry)A dispersion is a system in which particles are dispersed in a continuous phase of a different composition . See also emulsion. A dispersion is classified in a number of different ways, including how large the particles are in relation to the particles of the continuous phase, whether or not...
- OpacityOpacity (optics)Opacity is the measure of impenetrability to electromagnetic or other kinds of radiation, especially visible light. In radiative transfer, it describes the absorption and scattering of radiation in a medium, such as a plasma, dielectric, shielding material, glass, etc...
or transparency - Resistance to alkalis and acids
- Reactions and interactions between pigments
Swatches
Pure pigments reflect light in a very specific way that cannot be precisely duplicated by the discrete light emitters in a computer displayComputer display
A monitor or display is an electronic visual display for computers. The monitor comprises the display device, circuitry, and an enclosure...
. However, by making careful measurements of pigments, close approximations can be made. The Munsell Color System
Munsell color system
In colorimetry, the Munsell color system is a color space that specifies colors based on three color dimensions: hue, value , and chroma . It was created by Professor Albert H...
provides a good conceptual explanation of what is missing. Munsell devised a system that provides an objective measure of color in three dimensions: hue, value (or lightness), and chroma. Computer displays in general are unable to show the true chroma of many pigments, but the hue and lightness can be reproduced with relative accuracy. However, when the gamma of a computer display deviates from the reference value, the hue is also systematically biased.
The following approximations assume a display device at gamma
Gamma correction
Gamma correction, gamma nonlinearity, gamma encoding, or often simply gamma, is the name of a nonlinear operation used to code and decode luminance or tristimulus values in video or still image systems...
2.2, using the sRGB color space
SRGB color space
sRGB is a standard RGB color space created cooperatively by HP and Microsoft in 1996 for use on monitors, printers, and the Internet.sRGB uses the ITU-R BT.709 primaries, the same as are used in studio monitors and HDTV, and a transfer function typical of CRTs...
. The further a display device deviates from these standards, the less accurate these swatches will be. Swatches are based on the average measurements of several lots of single-pigment watercolor paints, converted from Lab color space
Lab color space
A Lab color space is a color-opponent space with dimension L for lightness and a and b for the color-opponent dimensions, based on nonlinearly compressed CIE XYZ color space coordinates....
to sRGB color space
SRGB color space
sRGB is a standard RGB color space created cooperatively by HP and Microsoft in 1996 for use on monitors, printers, and the Internet.sRGB uses the ITU-R BT.709 primaries, the same as are used in studio monitors and HDTV, and a transfer function typical of CRTs...
for viewing on a computer display. Different brands and lots of the same pigment may vary in color. Furthermore, pigments have inherently complex reflectance spectra that will render their color appearance greatly different depending on the spectrum of the source illumination
Standard illuminant
A standard illuminant is a theoretical source of visible light with a profile which is published. Standard illuminants provide a basis for comparing images or colors recorded under different lighting.-CIE illuminants:...
; a property called metamerism
Metamerism (color)
In colorimetry, metamerism is the matching of apparent color of objects with different spectral power distributions. Colors that match this way are called metamers....
. Averaged measurements of pigment samples will only yield approximations of their true appearance under a specific source of illumination. Computer display systems use a technique called chromatic adaptation transforms to emulate the correlated color temperature of illumination sources, and cannot perfectly reproduce the intricate spectral combinations originally seen. In many cases the perceived color of a pigment falls outside of the gamut
Gamut
In color reproduction, including computer graphics and photography, the gamut, or color gamut , is a certain complete subset of colors. The most common usage refers to the subset of colors which can be accurately represented in a given circumstance, such as within a given color space or by a...
of computer displays and a method called gamut mapping
Color management
In digital imaging systems, color management is the controlled conversion between the color representations of various devices, such as image scanners, digital cameras, monitors, TV screens, film printers, computer printers, offset presses, and corresponding media.The primary goal of color...
is used to approximate the true appearance. Gamut mapping trades off any one of Lightness
Lightness
Lightness is a philosophical concept most closely associated with continental philosophy and existentialism, which is used in ontology. The term "lightness" varies in usage but is differentiated from physical weight, such as "the lightness of balsa wood"...
, Hue
Hue
Hue is one of the main properties of a color, defined technically , as "the degree to which a stimulus can be describedas similar to or different from stimuli that are described as red, green, blue, and yellow,"...
or Saturation
Saturation (color theory)
In colorimetry and color theory, colorfulness, chroma, and saturation are related but distinct concepts referring to the perceived intensity of a specific color. Colorfulness is the degree of difference between a color and gray. Chroma is the colorfulness relative to the brightness of another color...
accuracy to render the color on screen, depending on the priority chosen in the conversion's ICC
International Color Consortium
The International Color Consortium was formed in 1993 by eight industry vendors in order to create a universal color management system that would function transparently across all operating systems and software packages....
rendering intent.
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Biological pigments
In biologyBiology
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...
, a pigment is any color
Color
Color or colour is the visual perceptual property corresponding in humans to the categories called red, green, blue and others. Color derives from the spectrum of light interacting in the eye with the spectral sensitivities of the light receptors...
ed material of plant or animal cells. Many biological structures, such as skin
Skin
-Dermis:The dermis is the layer of skin beneath the epidermis that consists of connective tissue and cushions the body from stress and strain. The dermis is tightly connected to the epidermis by a basement membrane. It also harbors many Mechanoreceptors that provide the sense of touch and heat...
, eye
Eye
Eyes are organs that detect light and convert it into electro-chemical impulses in neurons. The simplest photoreceptors in conscious vision connect light to movement...
s, fur
Fur
Fur is a synonym for hair, used more in reference to non-human animals, usually mammals; particularly those with extensives body hair coverage. The term is sometimes used to refer to the body hair of an animal as a complete coat, also known as the "pelage". Fur is also used to refer to animal...
and hair
Hair
Hair is a filamentous biomaterial, that grows from follicles found in the dermis. Found exclusively in mammals, hair is one of the defining characteristics of the mammalian class....
contain pigments (such as melanin
Melanin
Melanin is a pigment that is ubiquitous in nature, being found in most organisms . In animals melanin pigments are derivatives of the amino acid tyrosine. The most common form of biological melanin is eumelanin, a brown-black polymer of dihydroxyindole carboxylic acids, and their reduced forms...
).
Animal skin coloration
Animal colouration
Animal coloration is the general appearance of an animal resulting from the reflection or emission of light from its surfaces. The mechanisms for colour production in animals include pigments, chromatophores, structural coloration, and bioluminescence....
is often achieved with specialized cells called chromatophores, which in animals such as the octopus
Octopus
The octopus is a cephalopod mollusc of the order Octopoda. Octopuses have two eyes and four pairs of arms, and like other cephalopods they are bilaterally symmetric. An octopus has a hard beak, with its mouth at the center point of the arms...
and chameleon
Chameleon
Chameleons are a distinctive and highly specialized clade of lizards. They are distinguished by their parrot-like zygodactylous feet, their separately mobile and stereoscopic eyes, their very long, highly modified, and rapidly extrudable tongues, their swaying gait, the possession by many of a...
can be controlled to vary the animal's color. Many conditions affect the levels or nature of pigments in plant, animal, some protista, or fungus
Fungus
A fungus is a member of a large group of eukaryotic organisms that includes microorganisms such as yeasts and molds , as well as the more familiar mushrooms. These organisms are classified as a kingdom, Fungi, which is separate from plants, animals, and bacteria...
cells. For instance, Albinism
Albinism
Albinism is a congenital disorder characterized by the complete or partial absence of pigment in the skin, hair and eyes due to absence or defect of an enzyme involved in the production of melanin...
is a disorder affecting the level of melanin production in animals.
Pigmentation is used in organisms for many biological purposes including Camouflage
Camouflage
Camouflage is a method of concealment that allows an otherwise visible animal, military vehicle, or other object to remain unnoticed, by blending with its environment. Examples include a leopard's spotted coat, the battledress of a modern soldier and a leaf-mimic butterfly...
, Mimicry, Aposematism
Aposematism
Aposematism , perhaps most commonly known in the context of warning colouration, describes a family of antipredator adaptations where a warning signal is associated with the unprofitability of a prey item to potential predators...
(warning), Sexual selection
Sexual selection
Sexual selection, a concept introduced by Charles Darwin in his 1859 book On the Origin of Species, is a significant element of his theory of natural selection...
and other forms of Signalling
Signalling theory
Within evolutionary biology, signalling theory is a body of theoretical work examining communication between individuals. The central question is when organisms with conflicting interests should be expected to communicate "honestly"...
, Photosynthesis
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
(in plants), as well as basic physical purposes such as protection from Sunburn
Sunburn
A sunburn is a burn to living tissue, such as skin, which is produced by overexposure to ultraviolet radiation, commonly from the sun's rays. Usual mild symptoms in humans and other animals include red or reddish skin that is hot to the touch, general fatigue, and mild dizziness. An excess of UV...
.
Pigment color differs from structural color in that it is the same for all viewing angles, whereas structural color is the result of selective reflection or iridescence
Iridescence
Iridescence is generally known as the property of certain surfaces which appear to change color as the angle of view or the angle of illumination changes...
, usually because of multilayer structures. For example, butterfly
Butterfly
A butterfly is a mainly day-flying insect of the order Lepidoptera, which includes the butterflies and moths. Like other holometabolous insects, the butterfly's life cycle consists of four parts: egg, larva, pupa and adult. Most species are diurnal. Butterflies have large, often brightly coloured...
wings typically contain structural color, although many butterflies have cells that contain pigment as well.
Pigments by chemical composition
- CadmiumCadmiumCadmium is a chemical element with the symbol Cd and atomic number 48. This soft, bluish-white metal is chemically similar to the two other stable metals in group 12, zinc and mercury. Similar to zinc, it prefers oxidation state +2 in most of its compounds and similar to mercury it shows a low...
pigments: cadmium yellow, cadmium red, cadmium greenCadmium pigmentsCadmium pigments are a class of pigments that have cadmium as one of the chemical components. They are highly toxic and can produce cadmium poisoning. Most of cadmium produced worldwide is used in the production of nickel-cadmium batteries, but about half the remaining consumption, which is about...
, cadmium orangeCadmium pigmentsCadmium pigments are a class of pigments that have cadmium as one of the chemical components. They are highly toxic and can produce cadmium poisoning. Most of cadmium produced worldwide is used in the production of nickel-cadmium batteries, but about half the remaining consumption, which is about... - CarbonCarbonCarbon is the chemical element with symbol C and atomic number 6. As a member of group 14 on the periodic table, it is nonmetallic and tetravalent—making four electrons available to form covalent chemical bonds...
pigments: carbon blackCarbon blackCarbon black is a material produced by the incomplete combustion of heavy petroleum products such as FCC tar, coal tar, ethylene cracking tar, and a small amount from vegetable oil. Carbon black is a form of amorphous carbon that has a high surface-area-to-volume ratio, although its...
(including vine blac, lamp black), ivory black (bone char) - ChromiumChromiumChromium is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable...
pigments: chrome yellowChrome yellowChrome Yellow is a natural yellow pigment made of lead chromate . It was first extracted from the mineral crocoite by the French chemist Louis Vauquelin in 1809...
and chrome greenChromium(III) oxideChromium oxide is the inorganic compound of the formula Cr2O3. It is one of principal oxides of chromium and is used as a pigment. In nature, it occurs as the rare mineral eskolaite.-Structure and properties:... - CobaltCobaltCobalt is a chemical element with symbol Co and atomic number 27. It is found naturally only in chemically combined form. The free element, produced by reductive smelting, is a hard, lustrous, silver-gray metal....
pigments: cobalt violet, cobalt blueCobalt blueCobalt blue is a cool, slightly desaturated blue color, historically made using cobalt salts of alumina. It is used in certain ceramics and painting; the different cobalt pigment smalt, based on silica, is more often used directly in tinted transparent glasses...
, cerulean blue, aureolinAureolinAureolin is a pigment used in oil and watercolor painting. Its color index name is PY40 . It was first made in 1848 by N. W. Fischer in Breslau and its chemical composition is potassium cobaltinitrite.Aureolin is rated as permanent in oils but darkens and fades easily in watercolors...
(cobalt yellow) - CopperCopperCopper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
pigments: AzuriteAzuriteAzurite is a soft, deep blue copper mineral produced by weathering of copper ore deposits. It is also known as Chessylite after the type locality at Chessy-les-Mines near Lyon, France...
, Han purpleHan PurpleHan purple and Han blue are synthetic barium copper silicate pigments that were developed in China at least 2,000 years ago....
, Han blue, Egyptian blueEgyptian BlueEgyptian blue is chemically known as calcium copper silicate . It is a pigment used by Egyptians for thousands of years. It is considered to be the first synthetic pigment. The pigment was known to the Romans by the name caeruleum...
, MalachiteMalachiteMalachite is a copper carbonate mineral, with the formula Cu2CO32. This green-colored mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses. Individual crystals are rare but do occur as slender to acicular prisms...
, Paris greenParis GreenParis Green is an inorganic compound more precisely known as copper acetoarsenite. It is a highly toxic emerald-green crystalline powder that has been used as a rodenticide and insecticide, and also as a pigment, despite its toxicity. It is also used as a blue colorant for fireworks...
, Phthalocyanine Blue BNPhthalocyanine Blue BNPhthalocyanine Blue BN, also called monastral blue, phthalo blue , is a bright, greenish-blue crystalline synthetic blue pigment from the group of phthalocyanine dyes....
, Phthalocyanine Green GPhthalocyanine Green GPhthalocyanine Green G, also called phthalo green, Pigment Green 7, Copper Phthalocyanine Green, C.I. Pigment Green 42, Non-flocculating Green G, Polychloro copper phthalocyanine, or C.I. 74260, is a synthetic green pigment from the group of phthalocyanine dyes, a complex of copper with chlorinated...
, verdigrisVerdigrisVerdigris is the common name for a green pigment obtained through the application of acetic acid to copper plates or the natural patina formed when copper, brass or bronze is weathered and exposed to air or seawater over a period of time. It is usually a basic copper carbonate, but near the sea...
, viridianViridianViridian is a blue-green pigment, a hydrated chromium oxide, of medium saturation and relatively dark in value. It is composed more of green than blue. Specifically, it is a dark shade of spring green, the color between green and cyan on the color wheel... - Iron oxideIron oxideIron oxides are chemical compounds composed of iron and oxygen. All together, there are sixteen known iron oxides and oxyhydroxides.Iron oxides and oxide-hydroxides are widespread in nature, play an important role in many geological and biological processes, and are widely utilized by humans, e.g.,...
pigments: sanguineSanguineSanguine is chalk of a reddish color, often called the true colour of blood. tending to brown, used in drawing, The word also describes any drawing done in sanguine.-Technique:...
, caput mortuumCaput mortuumCaput Mortuum is a Latin term whose literal meaning is "dead head" or "worthless remains", used in alchemy and also as the name of a pigment.-Alchemy and chemistry:...
, oxide red, red ochre, Venetian redVenetian redVenetian red is a light and warm pigment that is a darker shade of scarlet, derived from nearly pure ferric oxide of the hematite type. Modern versions are frequently made with synthetic red iron oxide.-Venetian red:...
, Prussian bluePrussian bluePrussian blue is a dark blue pigment with the idealized formula Fe718. Another name for the color Prussian blue is Berlin blue or, in painting, Parisian blue. Turnbull's blue is the same substance but is made from different reagents.... - Clay earth pigmentClay earth pigmentClay earth pigments are naturally occurring minerals, principally iron oxides, that have been used since prehistoric times as pigments. The primary types are*ochre*sienna*umber...
s (iron oxides): yellow ochre, raw siennaSiennaSienna is a form of limonite clay most famous in the production of oil paint pigments. Its yellow-brown colour comes from ferric oxides contained within...
, burnt sienna, raw umber, burnt umber. - LeadLeadLead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
pigments: lead white, cremnitz white, Naples yellowNaples YellowNaples yellow, also called antimony yellow, can range from a somewhat muted, or earthy, reddish yellow pigment to a bright light yellow, and is the chemical compound lead antimonate. Its chemical composition is Pb2/Pb32. It is also known as jaune d'antimoine. It is one of the oldest synthetic...
, red leadRed leadLead tetroxide, also called minium, red lead or triplumbic tetroxide, is a bright red or orange crystalline or amorphous pigment. Chemically, red lead is lead tetroxide, Pb3O4, or 2PbO·PbO2.... - MercuryMercury (element)Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...
pigments: vermilionVermilionVermilion is an opaque orangish red pigment, similar to scarlet. As a naturally occurring mineral pigment, it is known as cinnabar, and was in use around the world before the Common Era began. Most naturally produced vermilion comes from cinnabar mined in China, and vermilion is nowadays commonly... - TitaniumTitaniumTitanium is a chemical element with the symbol Ti and atomic number 22. It has a low density and is a strong, lustrous, corrosion-resistant transition metal with a silver color....
pigments: titanium yellowTitanium yellowTitanium yellow, also nickel antimony titanium yellow, nickel antimony titanium yellow rutile, CI Pigment Yellow 53, or C.I. 77788, is a yellow pigment with the chemical composition of NiO.Sb2O5.20TiO2. Its CAS number is . It is a complex inorganic compound. Its melting point lies above 1000 °C,...
, titanium beige, titanium whiteTitanium dioxideTitanium dioxide, also known as titanium oxide or titania, is the naturally occurring oxide of titanium, chemical formula . When used as a pigment, it is called titanium white, Pigment White 6, or CI 77891. Generally it comes in two different forms, rutile and anatase. It has a wide range of...
, titanium blackTitanium(III) oxideTitanium oxide is a chemical compound of titanium and oxygen. It is prepared by reacting titanium dioxide with titanium metal at 1600°C.... - UltramarineUltramarineUltramarine is a blue pigment consisting primarily of a double silicate of aluminium and sodium with some sulfides or sulfates, and occurring in nature as a proximate component of lapis lazuli...
pigments: ultramarineUltramarineUltramarine is a blue pigment consisting primarily of a double silicate of aluminium and sodium with some sulfides or sulfates, and occurring in nature as a proximate component of lapis lazuli...
, ultramarine green shade - ZincZincZinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
pigments: zinc white, zinc ferriteZinc ferriteZinc ferrites are a series of synthetic inorganic compounds of zinc and iron with the general formula of ZnxFe3-xO4. Zinc ferrite compounds can be prepared by aging solutions of Zn2, Fe3, and triethanolamine in the presence and in the absence of hydrazine, or reacting iron oxides and zinc oxide...
Biological and organic
- Biological origins: alizarinAlizarinAlizarin or 1,2-dihydroxyanthraquinone is an organic compound with formula that has been used throughout history as a prominent dye, originally derived from the roots of plants of the madder genus.Alizarin was used as a red dye for the English parliamentary "new model" army...
(synthesized), alizarin crimsonAlizarinAlizarin or 1,2-dihydroxyanthraquinone is an organic compound with formula that has been used throughout history as a prominent dye, originally derived from the roots of plants of the madder genus.Alizarin was used as a red dye for the English parliamentary "new model" army...
(synthesized), gambogeGambogeGamboge is a partially transparent dark mustard yellow pigment.Other forms and spellings are: cambodia, cambogium, camboge, cambugium, gambaugium, gambogia, gambozia, gamboidea, gambogium, gumbouge, gambouge, gamboge, gambooge, gambugia...
, cochineal redCarmineCarmine , also called Crimson Lake, Cochineal, Natural Red #4, C.I. 75470, or E120, is a pigment of a bright-red color obtained from the aluminum salt of carminic acid, which is produced by some scale insects, such as the cochineal beetle and the Polish cochineal, and is used as a general term for...
, rose madderRose madderRose Madder is the commercial name sometimes used to designate a paint made from the pigment Madder Lake - a traditional lake pigment, extracted from the common madder plant ....
, indigoIndigo dyeIndigo dye is an organic compound with a distinctive blue color . Historically, indigo was a natural dye extracted from plants, and this process was important economically because blue dyes were once rare. Nearly all indigo dye produced today — several thousand tons each year — is synthetic...
, Indian yellowIndian YellowIndian yellow, also called euxanthin or euxanthine, is a xanthonoid. It is transparent yellow pigment used in oil paint. Chemically it is a magnesium euxanthate, the magnesium salt of euxanthic acid. It is a clear, deep and luminescent yellow pigment...
, Tyrian purpleTyrian purpleTyrian purple , also known as royal purple, imperial purple or imperial dye, is a purple-red natural dye, which is extracted from sea snails, and which was possibly first produced by the ancient Phoenicians... - Non biological organic: quinacridoneQuinacridoneQuinacridone is a red powder. It is an organic compound with the molecular formula C20H12N2O2. It is used as a pigment; analogs bearing this motif are known as quinacridones.-Quinacridones:...
, magentaMagentaMagenta is a color evoked by light stronger in blue and red wavelengths than in yellowish-green wavelengths . In light experiments, magenta can be produced by removing the lime-green wavelengths from white light...
, phthalo green, phthalo blue, pigment red 170Pigment Red 170Naphthol Red is an organic pigment extensively used in automotive coatings and painting.It is produced synthetically by converting p-aminobenzamide into the corresponding diazonium compound followed by diazotation with 3-hydroxy-2-naphththoic acid anilide.In the solid state the hydrazo tautomer...
External links
- Pigments through the ages
- Earliest evidence of art found
- Sarah Lowengard, The Creation of Color in Eighteenth-century Europe, Columbia University Press, 2006
- Phillip Ball, (audio) On Chemistry and Colour in Art
- Glaze and Body Pigments and Stains in the Ceramic Tile Industry