Pages in category "Organic pigments"
The following 38 pages are in this category, out of 38 total. This list may not reflect recent changes (learn more).
The following 38 pages are in this category, out of 38 total. This list may not reflect recent changes (learn more).
1. Alizarin – Alizarin or 1, 2-dihydroxyanthraquinone is an organic compound with formula C 14H 8O4 that has been used throughout history as a prominent red dye, principally for dyeing textile fabrics. Historically it was derived from the roots of plants of the madder genus, in 1869, it became the first natural pigment to be duplicated synthetically. Alizarin is the ingredient for the manufacture of the madder lake pigments known to painters as Rose madder. A notable use of alizarin in modern times is as an agent in biological research because it stains free calcium. Alizarin continues to be used commercially as a red textile dye, Madder has been cultivated as a dyestuff since antiquity in central Asia and Egypt, where it was grown as early as 1500 BC. Cloth dyed with madder root pigment was found in the tomb of the Pharaoh Tutankhamun and in the ruins of Pompeii, in the Middle Ages, Charlemagne encouraged madder cultivation. Madder was widely used as a dye in Western Europe in the Late Medieval centuries, in 17th century England, alizarin was used as a red dye for the clothing of the parliamentary New Model Army. The distinctive red color would continue to be worn for centuries, giving English, the madder dyestuff is combined with a dye mordant. According to which mordant used, the color may be anywhere from pink through purple to dark brown. In the 18th century the most valued color was a bright red known as Turkey Red, the combination of mordants and overall technique used to obtain the Turkey Red originated in the Middle East or Turkey. It was a complex and multi-step technique in its Middle Eastern formulation, the process was simplified in late 18th-century Europe. This resulting madder lake has a color, and can be used more efficaciously. This general method of preparing lakes has been known for centuries but was simplified in the late 18th, in 1826, the French chemist Pierre-Jean Robiquet found that madder root contained two colorants, the red alizarin and the more rapidly fading purpurin. About the same time, the English dye chemist William Henry Perkin independently discovered the same synthesis, the subsequent discovery that anthracene could be abstracted from coal tar further advanced the importance and affordability of alizarins artificial synthesis. The synthetic alizarin could be produced for a fraction of the cost of the product. The principal synthesis entailed oxidation of anthraquinone-2-sulfonic acid with sodium nitrate in concentrated sodium hydroxide, Alizarin itself has been in turn largely replaced today by the more light-resistant quinacridone pigments developed at DuPont in 1958. Alizarin is one of ten dihydroxyanthraquinone isomers and its molecular structure can be viewed as being derived from anthraquinone by replacement of two neighboring hydrogen atoms by hydroxyl groups. It is soluble in hexane and chloroform, and can be obtained from the latter as red-purple crystals, Alizarin changes color depending on the pH of the solution it is in, thereby making it a pH indicator
2. Anthoxanthin – Anthoxanthins are a type of flavonoid pigments in plants. Anthoxanthins are water-soluble pigments which range in color from white or colorless to a creamy to yellow and these pigments are generally whiter in an acid medium and yellowed in an alkaline medium. They are very susceptible to changes with minerals and metal ions. As with all flavonoids, they exhibit antioxidant properties, and are important in nutrition, darkening with iron is particularly prominent in food products. They are considered to have more variety than anthocyanins
3. Arylide yellow – Arylide yellow, also known as Hansa yellow and monoazo yellow, are a family of organic compounds used as pigments. They are primarily used as industrial colorants including plastics, building paints and they are also used in artistic oil paints, acrylics and watercolors. These pigments are usually semi-transparent yellows and yellow-greens, related organic pigments are the diarylide pigments. Overall, these pigments have partially displaced the toxic cadmium yellow in the marketplace, painters such as Alexander Calder and Jackson Pollock are known to have employed arylide yellow in their artworks. The compound is obtained by azo coupling of aniline and acetoacetanilide or their derivatives, the class of compounds was discovered in Germany in 1909. Members of this include, Pigment Yellow 6, derived from 4-chloro-2-nitroaniline and aniline to produce medium yellows. Pigment Yellow 3, derived from 4-chloro-2-nitroaniline and 2-chloroaniline to produce greenish-yellows, Pigment Yellow 16 derived from 2, 4-dichloroaniline and tolidine to produce medium-yellows. Pigment Yellow 74, derived from 2-methoxy-4-nitroaniline and 2-methoxyaniline to produce greenish-yellows, list of colors Microstructural Characteristics of Paint Pigments A Deep Technical Insight On Arylide Yellow Organic Pigments Arylide Yellow GY - Pigment Yellow 74 Industries Details
4. Azo dye – 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, the more stable derivatives contain two aryl groups. The N=N group is called an azo group, the name azo comes from azote, the French name for nitrogen that is derived from the Greek ἀ- + ζωή. Most colored textile and leather articles are treated with azo dyes, as a consequence of п-delocalization, aryl azo compounds have vivid colors, especially reds, oranges, and yellows. Therefore, they are used as dyes, and are known as azo dyes. Some azo compounds, e. g. methyl orange, are used as acid-base indicators due to the different colors of their acid, most DVD-R/+R and some CD-R discs use blue azo dye as the recording layer. The development of azo dyes was an important step in the development of the chemical industry, azo pigments consist of colorless particles colored using an azo compound. Azo pigments are important in a variety of paints including artists paints and they have excellent coloring properties, again mainly in the yellow to red range, as well as good lightfastness. The lightfastness depends not only on the properties of the azo compound. Aryl azo compounds are stable, crystalline species. Azobenzene is the prototypical aromatic azo compound and it exists mainly as the trans isomer, but upon photolysis, converts to the cis isomer. The oxidation of hydrazines also gives azo compounds, typical aniline partners are shown below. Illustrative azo compounds that are precursors to dyes Aliphatic azo compounds are commonly encountered than the aryl azo compounds. A commercially important alkyl azo compound is azobisisobutyronitrile, which is used as an initiator in free radical polymerizations. A simple dialkyl diazo compound is diethyldiazene, EtN=NEt, because of their instability, aliphatic azo compounds pose the risk of explosion. Likewise, several studies have linked azo pigments with basal cell carcinoma. Azo dyes derived from benzidine are carcinogens, exposure to them has classically been associated with bladder cancer, accordingly, the production of benzidine azo dyes was discontinued in the 1980s in the most important western industrialized countries. Certain azo dyes can break down under reductive conditions to any of a group of defined aromatic amines
5. Bistre – Bistre can refer to two things, a very dark shade of grayish black, a shade of brown made from soot, or the name for a color resembling the brownish pigment. Bistres appearance is generally of a grayish brown, with a yellowish cast. Beechwood was burned to produce the soot, which was boiled and diluted with water, many Old Masters used bistre as the ink for their drawings. The first recorded use of bistre as a name in English was in 1727. At right is displayed the color brown, a medium brownish tone of the color bistre. This is the tone of bistre that most closely matches the sample in the 1930 book A Dictionary of Color by Maerz. This tone of bistre is the color of the ink that was used by the Old Masters for their drawings, the source of this color is, ISCC-NBS Dictionary of Color Names --Color Sample of Bistre. At right is displayed the color French bistre, which is the tone of bistre called bistre in the Pourpre. com color list, for pictures of bistre colored postage stamps, see the article on the color Bistre in the French Wikipedia
6. Bone char – Bone char is a porous, black, granular material produced by charring animal bones. Its composition varies depending on how it is made, however, it consists mainly of tricalcium phosphate 57–80%, calcium carbonate 6–10% and it is primarily used for filtration and decolorization. Bone char is primarily made from cow bones, however, to prevent the spread of Creutzfeldt–Jakob disease, the skull and spine are never used. Most of the material in the bones is driven off by heat, and was historically collected as Dippels oil. Heating bones in an oxygen-rich atmosphere gives bone ash, which is quite different. Used bone char can be regenerated by washing with hot water to remove impurities, the tricalcium phosphate in bone char can be used to remove fluoride and metal ions from water, making it useful for the treatment of drinking supplies. Bone charcoal is the oldest known water defluoridation agent and was used in the United States from the 1940s through to the 1960s. As it can be generated cheaply and locally it is used in certain developing countries. Bone chars usually have lower surface areas than activated carbons, but present high adsorptive capacities for certain metals, other highly toxic metal ions, such as those of arsenic and lead may also be removed. Historically, bone char was often used in sugar refining as a decolorising and deashing agent, particularly in cane sugar as this contains more colored impurities. It has largely fallen out of use, particularly in the US and Europe, mainly for economic reasons but also due to the concerns of vegetarians and vegans, as well as various religious groups. The removal of these is beneficial, as it reduces the level of scaling later in the refining process, modern alternatives to bone char include activated carbon and ion-exchange resins. Bone black and ivory black are artists pigments which are in use since historic times by such as Rembrandt and Velázquez. The black dresses and high hats of the gentlemen in Manets Music in the Tuileries are painted in ivory black, ivory black was formerly made by grinding charred ivory in oil. Today ivory black is considered a synonym for bone black, actual ivory is no longer used because of the expense and because animals who are natural sources of ivory are subject to international control as endangered species. It is used to refine crude oil in the production of petroleum jelly, the production of bone char was featured on the Discovery Channels TV series Dirty Jobs, on episode 24 of season 4, Bone Black, originally broadcast on 9 February 2010. Human bone char, referred to as bone charcoal, is mentioned in Thomas Pynchons novel The Crying of Lot 49. The bones come from US soldiers who died in combat during WWII and were buried in a lake in Italy, pot ash Carbon black Activated carbon Blacks
7. Caput mortuum – Caput 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. The symbol shown on this page was used in 18th-century chemistry to mean residue. Caput mortuum was also used to mean crocus metallorum, i. e. brownish-red metallic compounds such as crocus martis. Caput mortuum, also known as purple, is the name given to a purple variety of haematite iron oxide pigment, used in oil paints. It was a popular colour for painting the robes of religious figures. The name for this pigment may have come from the alchemical usage, since iron oxide is the useless residue of oxidization
8. Carmine – Carmine, also called cochineal, cochineal extract, crimson lake or carmine lake, natural red 4, C. I. 75470, or E120, is a pigment of a bright-red color obtained from the salt of carminic acid. The pigment is produced from some scale insects such as the cochineal scale, the English word carmine is derived from the French word carmin, from Medieval Latin carminium, from Arabic qirmiz, which itself derives from Middle Persian carmir. The Persian term carmir might come from Sanskrit krimiga, from krmi The term may also be influenced in Latin by minium, purity of color is ensured by the absence of iron. Stannous chloride, citric acid, borax, or gelatin may be added to regulate the formation of the precipitate. For shades of purple, lime is added to the alum, thus, Carmine may be prepared from cochineal, by boiling dried insects in water to extract the carminic acid and then treating the clear solution with alum. Other common substances such as cream of tartar, stannous chloride, or potassium hydrogen oxalate can also be used to effect the precipitation, use of these chemicals causes the coloring and animal matters present in the liquid to be precipitated to give a lake pigment. Aluminum from the alum gives the traditional color to carminic acid precipitates. This color is degraded by the presence of iron salts, addition of lime can give carminic acid lakes a purple cast. Other methods for the production of dye are in use, in which egg white, fish glue. The quality of carmine is affected by the temperature and the degree of illumination during its preparation and it also differs according to the amount of alumina present in it. It is sometimes adulterated with cinnabar, starch and other materials, from these, good carmine should crumble readily between the fingers when dry. Carmine can be used as an agent in histology, as a Bests carmine to stain glycogen, mucicarmine to stain acidic mucopolysaccharides. In these applications, it is applied together with a mordant, Carmine was used in dyeing textiles and in painting since antiquity. It is not very stable in oil paint, and its use ceased after new, jacopo Tintoretto used carmine in several of his paintings, including Portrait of Vincenzo Morosini and Christ Washing the Feet of the Disciples. Carmine is used as a dye in many different products such as juices, ice cream, yogurt, and candy. Although principally a red dye, it is found in foods that are shades of red, pink. As a food dye it has known to cause severe allergic reactions
9. Crimson – Crimson is a strong, red color, inclining to purple. Crimson is produced using the bodies of the kermes insect, which were gathered commercially in Mediterranean countries, where they live on the kermes oak. Kermes dyes have been found in burial wrappings in Anglo-Scandinavian York, carmine is the name given to the dye made from the dried bodies of the female cochineal, although the name crimson is sometimes applied to these dyes too. Cochineal appears to have brought to Europe during the conquest of Mexico by the Spaniard Hernán Cortés. It was first described by Mathioli in 1549, the pigment is also called cochineal after the insect from which it is made. Alizarin is a pigment that was first synthesized in 1868 by the German chemists Carl Gräbe and Carl Liebermann, alizarin crimson is a dye bonded onto alum which is then used as a pigment and mixed with ochre, sienna and umber. The word crimson has been recorded in English since 1400, and its earlier forms include cremesin, crymysyn, German Karmesin, Italian Cremisi, French cramoisi, Portuguese carmesim, etc. The ultimate source may be Sanskrit कृमिज kṛmi-jā meaning worm-made, a shortened form of carmesinus also gave the Latin carminus, from which comes carmine. Other cognates include the Old Church Slavic čruminu, archaic Russian чермный, carmine dyes, which give crimson and related red and purple colors, are based on an aluminium and calcium salt of carminic acid. Carmine lake is an aluminium or aluminium-tin lake of cochineal extract, purple lake is prepared like carmine lake with the addition of lime to produce the deep purple tone. Carmine dyes tend to fade quickly, carmine dyes were once widely prized in both the Americas and in Europe. They were used in paints by Michelangelo and for the fabrics of the Hussars, the Turks, the British Redcoats. Nowadays carmine dyes are used for coloring foodstuffs, medicines and cosmetics, as a food additive in the European Union, carmine dyes are designated E120, and are also called cochineal and Natural Red 4. Carmine dyes are used in some oil paints and watercolors used by artists. The color pink is displayed on the right, the color pink has a hue code of 350, placing it directly within the range of crimson colors. Thus, the pink is actually a pale tint of crimson. The color Baker-Miller Pink is displayed on the right, Baker-Miller Pink was formulated in 1979. With a hue code of 344, Baker-Miller Pink is within the range of crimson colors, the color fandango pink is displayed on the right