natural organic pigments
Natural organic pigments were a significant part of historical pigments before the modern era, particularly for bodily ornamentation, cosmetics and textile dyeing.
For today's artists almost every natural organic pigment has been replaced by a synthetic organic alternative. These pigments only survive in their outmoded but quaint historical names, which commercial paint companies adopt to lend romance to their modern convenience mixtures.
Historically, the most important natural organic pigments in watercolors included:
• the many rose or crimson dyes from madder root, known since antiquity and extracted from the strong smelling powder made from dried, ground roots of several varieties of the herbaceous perennial rubia tinctorium, native to Greece and cultivated extensively throughout Asia Minor. The plant was brought to Italy by the returning Crusaders, but became important as an artists' pigment only after it was imported to Holland in the 16th century, which continued to supply most of the madder root used in Europe until the late 19th century. Madder was first manufactured as a laked pigment (madder lake) in around 1804, which greatly improved its permanence, and also afforded an expanded range of colors depending on the specific salt or substrate used in the laking process: rose madder or pink madder (NR9) in dyes laked on chalk or alum (aluminum hydrate), which can be made more brilliant by adding small quantities of stannous salts or by precipitating with calcium and sodium phosphates; deep red madder from precipitation on soda or potash; violet madder from the addition of iron sulfate; and various shades of brown madder from the addition of chromium alum or iron salts. Madder extracts actually contain several organic colorants, most of which are fugitive. The two most important were first separated and described by the French chemists Robiquet and Colin in 1826: orange purpurin and deep red alizarin (PR83). Both pigments are impermanent, but purpurin is especially fugitive, and is the source of genuine madder's warm, fiery color. The bluest lakes are made by preciptating pure alizarin on alumina.
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• deep red carmine (New World cochineal, NR4) is made from the dried bodies of female wingless scale insects (Dactylopius coccus) that feed on prickly pear or torch thistle cactus throughout Central America and Mexico. The carmine of antiquity (Old World kermes, NR3) was extracted from a similar insect, Kermes vermilio, that lives on scarlet oaks native to the Near East and the European side of the Mediterranean basin. Kermes carmine was used as a dye and a laked pigment in ancient Egypt, Greece and the near East and is one of the oldest organic pigments; cochineal carmine was used by the Aztecs and was first imported to Europe in the 1530's from Spanish conquests in America. Recipes for artists' use of carmine appear in many early painting and alchemical handbooks throughout the Middle Ages; the laking process for both pigments was improved in the 19th century. Carmine lakes appear frequently in European oil paintings from François Boucher to Raoul Dufy; in watercolors it has extremely poor lightfastness and has not been widely used since alizarin crimson became available in the late 19th century. The dye is still available today as a food coloring, and carmine is one of the few red pigments considered safe enough for use in eye cosmetics in the USA. The pigment madder carmine is made by adding an ammonia alkali solution of cochineal to a solution of alum and madder, then laking the mixture with soda crystals.
• deep brownish red indian lake or lac (NR25), made from the blood red secretion of female scale insects (Laccifer lacca) that feed on the twigs of various trees native to India, including Butea frondosa and Ficus religiosa. The twigs become encrusted with a reddish, bumpy and glossy resin which is processed to extract the red colorant; lighter grades of the resin are used as the basis for shellac. Used as a silk dye in India and imported to Spain since the early 13th century. Chemically lac is closely related to carmine, and is equally fugitive.
• the reddish dragon's blood (no CI name), a dark red resin exuded from the fruit of the rattan palm, Calamus draco, indigenous to eastern Asia, most often used as a colorant in varnishes, especially when applied over gold leaf, and very fugitive in watercolors.
• golden indian yellow (color index number 75320), made from the urine of cows fed exclusively mango leaves (as described under magnesium compounds); the urine was collected and evaporated, and the salty precipitate was formed by hand into balls that were sealed with a layer of mud, which were exported for processing into watercolor pigment. Apparently introduced into India from Persia in the 15th century, it was used in Mughal manuscript paintings from the late 16th to 19th centuries. Early European usage is attested in paintings by Vermeer, probably in pigment imported by the Dutch India company in the late 17th century. Available as a watercolor pigment in England from the late 18th century until 1921; paint production continued after that date from stockpiled raw pigment. The color is a deep yellow with a greenish fluorescence, but is only moderately lightfast.
• dull yellow natural gamboge (NY24), a moderately saturated middle yellow pigment made from the gum of the several species of garcinia tree, in particular Garcinia hanburyi, native throughout southeast Asia but cultivated primarily in Cambodia and India. The gum is collected by cutting grooves in the bark of the tree; the exuded sap dries into dark brown clumps which are ground into powder and treated with solvent to extract the pigment resin. Used in manuscript paintings in China and Japan since the 8th century up to the present day, and found in European watercolors from the early 17th through the 20th centuries. Winsor & Newton offered it as a very rarely used watercolor paint with poor lightfastness, but retired it in 2005.
• yellow or green pigments made since Roman times from the juice of parsley, flowers or berries, including sap green (no CI name), made from dried, ripe berries of plants in the buckthorn family (Rhamnus); Persian berries lake (no CI name), made from dried, unripe buckthorn berries, and especially popular in France and England during the 18th century. These and similar pigments are very fugitive.
• brown pink or stil-de-grain (no CI name), a deep yellowish brown lake made from the inner bark of a species of oak, Quercus tinctoria, indigenous to North America and commonly used in the 18th and early 19th centuries. Also very fugitive.
• dark blue indigo (NB1), an ancient and widespread colorant made from the fermented gray green leaves and flowering stalks of over 30 related plant species, including the medicinal indigo shrub (Indigofera tinctoria) native to India, dyer's woad (Isatis tinctoria) native to Europe, and dyer's knotgrass (Polygonum tinctorium). The dye was used in Chinese and Indian textiles since 2000 BCE, was known to ancient Egyptians as far back as the 16th century BCE, was mixed with the clay palygorskite and fired by the Mayans to make the ritual color Mayan blue, was mentioned as a dye in several Roman texts, and became common in Europe from the 13th century, both from domestic production (as woad) and as an import from the Middle East. The dye molecule was first artificially synthesized by A. Bäyer in 1870 (PB66), and this synthetic form was commercially available after 1897 from BASF (Germany). Indigo was common in watercolor painting from the 17th to the 19th centuries; it is still sometimes used in student watercolor paints and as the fading blue dye in denim fabrics.
• brown pigments made from deposits of peat or brown coal, known primarily under the name van dyke brown (NBr8), but also as Cologne earth or Cassel earth (after the German cities Köln and Kassel where the earliest and highest quality deposits of the pigment were mined), Kassel umber, Cullens earth or Rubens' brown. (In French sources, the name van dyke brown often refers to a calcined yellow ochre.) The pigments were first mentioned in early 17th century artists' handbooks, and were widely used in watercolors through the 19th century; the pigment is still mined today near Kassel. Holbein claims to offer the natural organic pigment in watercolors.
• dark brown sepia (no CI name), made from the ink of the cuttlefish sepia officinalis (a small squid mainly found in the Adriatic Sea), and extracted in more concentrated form using a process developed by Seydelmann in 1775.
• black pigments made from carbon obtained by burning wood (vine black, PBk8) or (in modern times) by burning tar or coal (lamp black, PBk6), and by slowly calcining ivory or bone in hot ovens (ivory black, PBk9; all modern supplies are made from bone, as ivory is an internationally banned product).
• I've left for dessert everyone's favorite, Egyptian mummy or caput mortuum (no CI name), a tarry brown pigment made from mummies excavated during the 18th to 19th centuries from ancient Egyptian communal tombs; these dried bodies had been embalmed with asphaltum (a petroleum residue) and resins. Pigment made by grinding up these carboniferous corpses was commonly available from the late 18th century up to 1925. (Winsor & Newton closely mimics this historical color in their caput mortuum violet.)
Despite the inadequate lightfastness and typically dull color appearance of these outmoded historical pigments, the names rose madder, brown madder, carmine, indian yellow, gamboge, sap green, indigo, van dyke brown and sepia are still frequently used as marketing monikers for watercolors made with completely unrelated and typically much more lightfast synthetic organic pigments. Use the color index names listed on the paint label to determine the actual pigments used in each case.
