Pigment

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A pigment is a colored material that is completely or nearly insoluble in water. Pigment_sentence_0

In contrast dyes are typically soluble, at least at some stage in their use. Pigment_sentence_1

Generally dyes are often organic compounds whereas pigments are often inorganic compounds. Pigment_sentence_2

Pigments of prehistoric and historic value include ocher, charcoal, and lapis lazuli. Pigment_sentence_3

Economic impact Pigment_section_0

In 2006, around 7.4 million tons of inorganic, organic and special pigments were marketed worldwide. Pigment_sentence_4

Estimated at around US$14.86 billion in 2018 and will rise at over 4.9% CAGR from 2019 to 2026. Pigment_sentence_5

The global demand on pigments was roughly US$20.5 billion in 2009. Pigment_sentence_6

According to an April 2018 report by Bloomberg Businessweek, the estimated value of the pigment industry globally is $30 billion. Pigment_sentence_7

The value of titanium dioxide – used to enhance the white brightness of many products – was placed at $13.2 billion per year, while the color Ferrari red is valued at $300 million each year. Pigment_sentence_8

Physical principles Pigment_section_1

Main article: Spectroscopy Pigment_sentence_9

Like all materials, the color of pigments arises because they absorb only certain wavelengths of visible light. Pigment_sentence_10

The bonding properties of the material determine the wavelength and efficiency of light absorption. Pigment_sentence_11

Light of other wavelengths are reflected or scattered. Pigment_sentence_12

The reflected light spectrum defines the color. Pigment_sentence_13

The appearance of pigments is sensitive to the source light. Pigment_sentence_14

Sunlight has a high color temperature and a fairly uniform spectrum. Pigment_sentence_15

Sunlight is considered a standard for white light. Pigment_sentence_16

Artificial light sources are less uniform. Pigment_sentence_17

Color spaces used to represent colors numerically must specify their light source. Pigment_sentence_18

Lab color measurements, unless otherwise noted, assume that the measurement was recorded under a D65 light source, or "Daylight 6500 K", which is roughly the color temperature of sunlight. Pigment_sentence_19

Other properties of a color, such as its saturation or lightness, may be determined by the other substances that accompany pigments. Pigment_sentence_20

Binders and fillers can affect the color. Pigment_sentence_21

History Pigment_section_2

Minerals have been used as colorants since prehistoric times. Pigment_sentence_22

Early humans used paint for aesthetic purposes such as body decoration. Pigment_sentence_23

Pigments and paint grinding equipment believed to be between 350,000 and 400,000 years old have been reported in a cave at Twin Rivers, near Lusaka, Zambia. Pigment_sentence_24

A favored blue pigment was derived from lapis lazuli. Pigment_sentence_25

Pigments based on minerals and clays often bear the name of the city or region where they were originally mined. Pigment_sentence_26

Raw Sienna and Burnt Sienna came from Siena, Italy, while Raw Umber and Burnt Umber came from Umbria. Pigment_sentence_27

These pigments were among the easiest to synthesize, and chemists created modern colors based on the originals. Pigment_sentence_28

These were more consistent than colors mined from the original ore bodies, but the place names remained. Pigment_sentence_29

Also found in many Paleolithic and Neolithic cave paintings are Red Ochre, anhydrous Fe2O3, and the hydrated Yellow Ochre (Fe2O3H2O). Pigment_sentence_30

Charcoal—or carbon black—has also been used as a black pigment since prehistoric times. Pigment_sentence_31

Synthetic pigments were introduced as early as the second millennium BCE. Pigment_sentence_32

White lead (basic lead carbonate, (PbCO3)2Pb(OH)2) is one of example. Pigment_sentence_33

and blue frit (Egyptian Blue). Pigment_sentence_34

Another early synthetic pigment is blue frit, calcium copper silicate, made by heating glass with a copper source, such as malachite. Pigment_sentence_35

Later premodern synthetic pigments include vermilion, verdigris, and lead-tin-yellow. Pigment_sentence_36

Vermilion, a mercury compound, was favored by old masters such as Titian. Pigment_sentence_37

Indian yellow was once produced by collecting the urine of cattle that had been fed only mango leaves. Pigment_sentence_38

Dutch and Flemish painters of the 17th and 18th centuries favored it for its luminescent qualities, and often used it to represent sunlight. Pigment_sentence_39

Since mango leaves are nutritionally inadequate for cattle, the practice of harvesting Indian yellow was eventually declared to be inhumane. Pigment_sentence_40

Modern hues of Indian yellow are made from synthetic pigments. Pigment_sentence_41

Vermillion has been parttially replaced in by cadmium reds. Pigment_sentence_42

Because of the expense of lapis lazuli, substitutes were often used. Pigment_sentence_43

Prussian blue, the oldest modern synthetic pigment, was discovered by accident in 1704. Pigment_sentence_44

By the early 19th century, synthetic and metallic blue pigments included French ultramarine, a synthetic form of lapis lazuli. Pigment_sentence_45

Ultramarine was manufactured by treating aluminium silicate with sulfur. Pigment_sentence_46

Various forms of Cobalt and Cerulean blue were also introduced. Pigment_sentence_47

In the early 20th century, Phthalo Blue, a synthetic metallo-organicc pigment was prepared. Pigment_sentence_48

At the same time, Royal Blue, 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 dioxide, or from inexpensive synthetic blue dyes. Pigment_sentence_49

The discovery in 1856 of mauveine, the first aniline dye, was a forerunner for the development of hundreds of synthetic dyes and pigments like azo and diazo compounds. Pigment_sentence_50

These dyes ushered in the flourishing of organic chemistry, including systematic designs of colorants.s. Pigment_sentence_51

The development of organic chemistry diminished the dependence on inorganic pigments. Pigment_sentence_52

Pigment_unordered_list_0

  • Paintings illustrating advances in pigmentsPigment_item_0_0
  • Pigment_item_0_1
  • Pigment_item_0_2
  • Pigment_item_0_3
  • Pigment_item_0_4

Manufacturing and industrial standard Pigment_section_3

Before the development of synthetic pigments, and the refinement of techniques for extracting mineral pigments, batches of color were often inconsistent. Pigment_sentence_53

With the development of a modern color industry, manufacturers and professionals have cooperated to create international standards for identifying, producing, measuring, and testing colors. Pigment_sentence_54

First published in 1905, the Munsell color system became the foundation for a series of color models, providing objective methods for the measurement of color. Pigment_sentence_55

The Munsell system describes a color in three dimensions, hue, value (lightness), and chroma (color purity), where chroma is the difference from gray at a given hue and value. Pigment_sentence_56

By the middle 20th century, standardized methods for pigment chemistry were available, part of an international movement to create such standards in industry. Pigment_sentence_57

The International Organization for Standardization (ISO) develops technical standards for the manufacture of pigments and dyes. Pigment_sentence_58

ISO standards define various industrial and chemical properties, and how to test for them. Pigment_sentence_59

The principal ISO standards that relate to all pigments are as follows: Pigment_sentence_60

Pigment_unordered_list_1

  • ISO-787 General methods of test for pigments and extenders.Pigment_item_1_5
  • ISO-8780 Methods of dispersion for assessment of dispersion characteristics.Pigment_item_1_6

Other ISO standards pertain to particular classes or categories of pigments, based on their chemical composition, such as ultramarine pigments, titanium dioxide, iron oxide pigments, and so forth. Pigment_sentence_61

Many manufacturers of paints, inks, textiles, plastics, and colors have voluntarily adopted the Colour Index International (CII) as a standard for identifying the pigments that they use in manufacturing particular colors. Pigment_sentence_62

First published in 1925—and now published jointly on the web by the Society of Dyers and Colourists (United Kingdom) and the American Association of Textile Chemists and Colorists (USA)—this index is recognized internationally as the authoritative reference on colorants. Pigment_sentence_63

It encompasses more than 27,000 products under more than 13,000 generic color index names. Pigment_sentence_64

In the CII schema, each pigment has a generic index number that identifies it chemically, regardless of proprietary and historic names. Pigment_sentence_65

For example, Phthalocyanine Blue BN has been known by a variety of generic and proprietary names since its discovery in the 1930s. Pigment_sentence_66

In much of Europe, phthalocyanine blue is better known as Helio Blue, or by a proprietary name such as Winsor Blue. Pigment_sentence_67

An American paint manufacturer, Grumbacher, registered an alternate spelling (Thanos Blue) as a trademark. Pigment_sentence_68

Colour Index International 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. Pigment_sentence_69

In the CII, all phthalocyanine blue pigments are designated by a generic color index number as either PB15 or PB16, short for pigment blue 15 and pigment blue 16; these two numbers reflect slight variations in molecular structure which produce a slightly more greenish or reddish blue. Pigment_sentence_70

Figures of merit Pigment_section_4

The following are some of the attributes of pigments that determine their suitability for particular manufacturing processes and applications: Pigment_sentence_71

Pigment_unordered_list_2

  • Lightfastness and sensitivity for damage from ultraviolet lightPigment_item_2_7
  • Heat stabilityPigment_item_2_8
  • ToxicityPigment_item_2_9
  • Tinting strengthPigment_item_2_10
  • StainingPigment_item_2_11
  • Dispersion (which can be measured with a Hegman gauge)Pigment_item_2_12
  • Opacity or transparencyPigment_item_2_13
  • Resistance to alkalis and acidsPigment_item_2_14
  • Reactions and interactions between pigmentsPigment_item_2_15

Swatches Pigment_section_5

Swatches are used to communicate colors accurately. Pigment_sentence_72

The types of swatches are dictated by the media, i.e., printing, computers, plastics, and textiles. Pigment_sentence_73

Generally, the medium that offers the broadest gamut of color shades is widely used across diverse media. Pigment_sentence_74

Printed swatches Pigment_section_6

Reference standards are provided by printed swatches of color shades. Pigment_sentence_75

PANTONE, RAL, Munsell, etc. are widely used standards of color communication across diverse media like printing, plastics, and textiles. Pigment_sentence_76

Plastic swatches Pigment_section_7

Companies manufacturing color masterbatches and pigments for plastics offer plastic swatches in injection molded color chips. Pigment_sentence_77

These color chips are supplied to the designer or customer to choose and select the color for their specific plastic products. Pigment_sentence_78

Plastic swatches are available in various special effects like pearl, metallic, fluorescent, sparkle, mosaic etc. Pigment_sentence_79

However, these effects are difficult to replicate on other media like print and computer display. Pigment_sentence_80

Plastic swatches have been created by 3D modelling to including various special effects. Pigment_sentence_81

Computer swatches Pigment_section_8

The appearance of pigments in natural light is difficult to replicate on a computer display. Pigment_sentence_82

Approximations are required. Pigment_sentence_83

The Munsell Color System provides an objective measure of color in three dimensions: hue, value (or lightness), and chroma. Pigment_sentence_84

Computer displays in general fail to show the true chroma of many pigments, but the hue and lightness can be reproduced with relative accuracy. Pigment_sentence_85

However, when the gamma of a computer display deviates from the reference value, the hue is also systematically biased. Pigment_sentence_86

The following approximations assume a display device at gamma 2.2, using the sRGB color space. Pigment_sentence_87

The further a display device deviates from these standards, the less accurate these swatches will be. Pigment_sentence_88

Swatches are based on the average measurements of several lots of single-pigment watercolor paints, converted from Lab color space to sRGB color space for viewing on a computer display. Pigment_sentence_89

The appearance of a pigment may depend on the brand and even the batch. Pigment_sentence_90

Furthermore, pigments have inherently complex reflectance spectra that will render their color appearance greatly different depending on the spectrum of the source illumination, a property called metamerism. Pigment_sentence_91

Averaged measurements of pigment samples will only yield approximations of their true appearance under a specific source of illumination. Pigment_sentence_92

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. Pigment_sentence_93

In many cases, the perceived color of a pigment falls outside of the gamut of computer displays and a method called gamut mapping is used to approximate the true appearance. Pigment_sentence_94

Gamut mapping trades off any one of lightness, hue, or saturation accuracy to render the color on screen, depending on the priority chosen in the conversion's ICC rendering intent. Pigment_sentence_95

Biological pigments Pigment_section_9

Main article: Biological pigment Pigment_sentence_96

In biology, a pigment is any colored material of plant or animal cells. Pigment_sentence_97

Many biological structures, such as skin, eyes, fur, and hair contain pigments (such as melanin). Pigment_sentence_98

Animal skin coloration often comes about through specialized cells called chromatophores, which animals such as the octopus and chameleon can control to vary the animal's color. Pigment_sentence_99

Many conditions affect the levels or nature of pigments in plant, animal, some protista, or fungus cells. Pigment_sentence_100

For instance, the disorder called albinism affects the level of melanin production in animals. Pigment_sentence_101

Pigmentation in organisms serves many biological purposes, including camouflage, mimicry, aposematism (warning), sexual selection and other forms of signalling, photosynthesis (in plants), as well as basic physical purposes such as protection from sunburn. Pigment_sentence_102

Pigment color differs from structural color in that pigment color is the same for all viewing angles, whereas structural color is the result of selective reflection or iridescence, usually because of multilayer structures. Pigment_sentence_103

For example, butterfly wings typically contain structural color, although many butterflies have cells that contain pigment as well. Pigment_sentence_104

Pigments by elemental composition Pigment_section_10

Main article: List of inorganic pigments Pigment_sentence_105

Pigment_unordered_list_3

Biological and organic Pigment_section_11

Pigment_unordered_list_4

See also Pigment_section_12

Pigment_unordered_list_5


Credits to the contents of this page go to the authors of the corresponding Wikipedia page: en.wikipedia.org/wiki/Pigment.