Source: Wikipedia Blue and links therefrom
What is Blue? Physics and Optics
Blue is the colour between violet and green on the optical spectrum of visible light. Human eyes perceive blue when observing light with a wavelength between 450 and 495 nanometres. Blues with a higher frequency and thus a shorter wavelength gradually look more violet, while those with a lower frequency and a longer wavelength gradually appear more green. Pure blue, in the middle, has a wavelength of 470 nanometres.
Blue recedes visually, being much quieter and less active than red. The clear sky and the deep sea appear blue because of an optical effect known as Rayleigh scattering. When sunlight passes through the atmosphere, the blue wavelengths are scattered more widely by the oxygen and nitrogen molecules, and more blue comes to our eyes. Rayleigh scattering also explains blue eyes; there is no blue pigment in blue eyes. Distant objects appear more blue because of another optical effect called atmospheric perspective.
Of the 3 primaries, blue is the darkest colour, and it has the greatest strength when deep. Identifying a pure, exact blue, is less easy than identifying red or yellow, particularly if there are no other varieties of blue adjacent for comparison.
The modern English word blue comes from Middle English bleu or blewe, from the Old French bleu, a word of Germanic origin, related to the Old High German word blao. In heraldry, the word azure is used for blue.
In Greek, Russian and some other languages, there is no single word for blue, but rather different words for light blue (Greek glaukos, Russian goluboy) and dark blue ( Greek kyaneos, Russian siniy).
Several languages, including Japanese, Thai, Korean, and Lakota Sioux, use the same word to describe blue and green. For example, in Vietnamese the colour of both tree leaves and the sky is xanh. In Japanese, the word for blue (青 ao) is often used for colours that English speakers would refer to as green, such as the colour of a traffic signal meaning “go”. (For more on this subject, see Distinguishing blue from green in language)
Blue was a latecomer among colours used in art and decoration, as well as language and literature. This is probably due to the perennial difficulty of making good blue dyes and pigments cheaply.
- woad in Europe – made from Isatis tinctoria, a flowering plant in the family Brassicaceae. This produced cheap inferior dyes.
- indigo in Asia and Africa derived from the plant Indigofera tinctoria and related species. In 1878 a German chemist named a. Von Baeyer discovered a synthetic substitute for indigotine, the active ingredient of indigo. This product gradually replaced natural indigo, and after the end of the First World War, it brought an end to the trade of indigo from the East and West Indies.
- Lapis lazuli or ultramarine, a semi-precious stone, has been mined in Badakshan, in the mountains of Afghanistan for more than three thousand years, and was exported to all parts of the ancient world. Refining out the impurities to create a rich and deep blue was a long and difficult process, and its transportation was also expensive. It was called bleu outremer in French and blu oltremare in Italian, since it came from the other side of the sea. In 1824 the Societé pour l’Encouragement d’Industrie in France offered a prize for the invention of an artificial ultramarine which could rival the natural colour made from lapis lazuli. The prize was won in 1826 by a chemist named Jean Baptiste Guimet, but he refused to reveal the formula of his colour. In 1828, another scientist, Christian Gmelin then a professor of chemistry in Tübingen, found the process and published his formula. This was the beginning of new industry to manufacture artificial ultramarine, which eventually almost completely replaced the natural product.
- Azurite, a form of copper carbonate, was often used as a substitute for ultramarine. The Romans used it under the name lapis armenius, or Armenian stone. The British called it azure of Amayne, or German azure. The Germans themselves called it bergblau, or mountain stone. It was mined in France, Hungary, Spain and Germany, and it made a pale blue with a hint of green, which was ideal for painting skies. It was a favourite background colour of the German painter Albrecht Dürer
- Egyptian blue, beginning in about 2500BC, was made by grinding silica, lime, copper, and alkalai, and heating it to 800 or 900 °C (1,470 or 1,650 °F). This is considered the first synthetic pigment. Egyptian blue was used to paint wood, papyrus and canvas, and was used to colour a glaze to make faience beads, inlays, and pots. It was particularly used in funeral statuary and figurines and in tomb paintings.
- tournesol or folium made from the plant Crozophora tinctoria, which grew in the south of France. It made a fine transparent blue valued in medieval manuscripts.
- smalt: which was made by grinding blue cobalt glass into a fine powder. It made a deep violet blue similar to ultramarine, and was vivid in frescoes and stained glass windows of the cathedrals of Saint-Denis and Chartres, but it lost some of its brilliance in oil paintings. It became especially popular in the 17th century, when ultramarine was difficult to obtain. It was employed at times by Titian, Tintoretto, Veronese, El Greco, Van Dyck, Rubens and Rembrandt.
- cobalt blue, a pigment of cobalt oxide-aluminium oxide, introduced it in 1802 by the French chemist Louis Jacques Thénard. This produced a deeper blue, similar to smalt. It was very stable but extremely expensive. It was a favourite of Auguste Renoir and Vincent van Gogh.
- cerulean blue??
- Prussian Blue (first called Berlin Blue) discovered accidentally in 1709 while experimenting with potassium and iron sulphides by a German druggist and pigment maker named Diesbach. The new colour was first called Berlin blue, but later became known as Prussian blue. By 1710 it was being used by the French painter Antoine Watteau, and later his successor Nicolas Lancret. It became immensely popular for the manufacture of wallpaper, and in the 19th century was widely used by French impressionist painters. Beginning in the 1820s, Prussian blue was imported into Japan through the port of Nagasaki. It was called bero-ai, or Berlin blue, and it became popular because it did not fade like traditional Japanese blue pigment, ai-gami, made from the dayflower. Prussian blue was used by both Hokusai, in his famous wave paintings, and Hiroshige.
- indanthrene a synthetic blue invented in 1901 which did not fade. By the 1950s almost all fabrics, including blue jeans, were dyed with the new synthetic dye. In 1970, BASF stopped making synthetic indigo, and switched to newer synthetic blues. Today almost all blue clothing is dyed with an indanthrone blue.
- The Chinese also created synthetic pigments, but the formula was not known in the west.
Conflicts between countries – control of use of woad, indigo and ultramarine and the search for ever cheaper and stabler blues often became a source of serious commercial competition.
Expressively blue is, above all, cool. Blue has associations of intangibility and passivity. It suggests a withdrawn, reflective mood.
- associated with the sky and with divinity. The Egyptian god Amun could make his skin blue so that he could fly, invisible, across the sky. Lapis Lazuli was used for the eyebrows on the funeral mask of King Tutankhamun (1341–1323 BC)
- protection against evil: many people around the Mediterranean still wear a blue amulet, representing the eye of God, to protect them from misfortune. To protect the dead against evil in the afterlife. Blue dye was also used to colour the cloth in which mummies were wrapped.
The ancient Greeks classified colours by whether they were light or dark, rather than by their hue. The Greek word for dark blue, kyaneos, could also mean dark green, violet, black or brown. The ancient Greek word for a light blue, glaukos, also could mean light green, grey, or yellow.
The Greeks imported indigo dye from India, calling it indikon. They used Egyptian blue in the wall paintings of Knossos, in Crete, (2100 BC). It was not one of the four primary colours for Greek painting described by Pliny the Elder (red, yellow, black, and white), but nonetheless it was used as a background colour behind the friezes on Greek temples and to colour the beards of Greek statues.
The Romans had many different words for varieties of blue, including caeruleus, caesius, glaucus, cyaneus, lividus, venetus, aerius, andferreus, but two words, both of foreign origin, became the most enduring; blavus, from the Germanic word blau, which eventually became bleu or blue; and azureus, from the Arabic word lazaward, which became azure.
- blue (made from imported indigo) was the colour of working class clothing; the nobles and rich wore white, black, red or violet.
- colour of mourning.
- colour of barbarians; Julius Caesar reported that the Celts and Germans dyed their faces blue to frighten their enemies, and tinted their hair blue when they grew old.
- indigo and Egyptian blue used for decoration. The walls of Roman villas in Pompeii had frescoes of brilliant blue skies, and blue pigments were found in the shops of colour merchants.
- In China, the colour blue is commonly associated with torment, ghosts, and death. In a traditional Chinese opera, a character with a face powdered blue is a villain.
South and South East Asia
- Blue in Hinduism: Many of the gods are depicted as having blue-coloured skin, particularly those associated with Vishnu, who is said to be the preserver of the world and thus intimately connected to water. Krishna and Ram, Vishnu’s avatars, are usually blue. Shiva, the destroyer, is also depicted in light blue tones and is called neela kantha, or blue-throated, for having swallowed poison in an attempt to turn the tide of a battle between the gods and demons in the gods’ favour. Blue is used to symbolically represent the fifth, throat, chakra (Vishuddha).
- In Thailand, blue is associated with Friday on the Thai solar calendar. Anyone may wear blue on Fridays and anyone born on a Friday may adopt blue as their colour.
In the Torah, the Israelites were commanded to put fringes, tzitzit, on the corners of their garments, and to weave within these fringes a “twisted thread of blue (tekhelet)”. In ancient days, this blue thread was made from a dye extracted from a Mediterranean snail called the hilazon. Maimonides claimed that this blue was the colour of “the clear noonday sky”; Rashi, the colour of the evening sky. According to several rabbinic sages, blue is the colour of God’s Glory.Staring at this colour aids in mediation, bringing us a glimpse of the “pavement of sapphire, like the very sky for purity”, which is a likeness of the Throne of God.(TheHebrew word for glory.) Many items in the Mishkan, the portable sanctuary in the wilderness, such as the menorah, many of the vessels, and the Ark of the Covenant, were covered with blue cloth when transported from place to place.
Blue was often used in pre-Islamic cultures:
- In Iran and Mesopotamia, lapis lazuli was used to make jewellery and vessels and to create the rich blues in Persian miniatures.
- The Ishtar Gate of ancient Babylon (604–562 BC) was decorated with deep blue glazed bricks used as a background for pictures of lions, dragons and aurochs.
- Dark blue Ground lapis was used in was widely used in the decoration of churches in the Byzantine Empire. Byzantine manuscripts as early as the 6th century, but it was impure and varied greatly in colour. In Byzantine art Christ and the Virgin Mary usually wore dark blue or purple. Blue was used as a background colour representing the sky in the magnificent mosaics which decorated Byzantine churches.
- Dark blue and turquoise decorative tiles were widely used to decorate the facades and interiors of mosques and palaces from Spain to Central Asia.
In the Islamic world, blue was of secondary importance to green, believed to be the favourite colour of the Prophet Mohammed. At certain times in Moorish Spain and other parts of the Islamic world, blue was the colour worn by Christians and Jews, because only Muslims were allowed to wear white and green.
- In Turkey and Central Asia, blue is the colour of mourning.
- The men of the Tuareg people in North Africa wear a blue turban called a tagelmust, which protects them from the sun and wind-blown sand of the Sahara desert. It is coloured with indigo. Instead of using dye, which uses precious water, the tagelmust is coloured by pounding it with powdered indigo. The blue colour transfers to the skin, where it is seen as a sign of nobility and affluence. Early visitors called them the “Blue Men” of the Sahara.
- In the culture of the Hopi people of the American southwest, blue symbolised the west, which was seen as the house of death. A dream about a person carrying a blue feather was considered a very bad omen.
Surveys in the US and Europe show that blue is the colour most commonly associated with harmony, faithfulness, confidence, distance, infinity, the imagination, cold, and sometimes with sadness. In US and European public opinion polls it is the most popular colour, chosen by almost half of both men and women as their favourite colour.
- early middle ages: blue played a minor role and only the poor wore blue clothing, coloured with poor-quality dyes made from the woad plant.
- Saint Denis Basilica in Paris rebuilt by Abbe Suger between 1130 and 1140 used cobalt combined red glass in the stained glass windows and filled the church with a bluish violet light. The church became the marvel of the Christian world, and the colour became known as the “bleu de Saint-Denis”. Even more elegant blue stained glass windows were installed in other churches, including at Chartres Cathedral and Sainte-Chapelle in Paris.
- 12th Century Roma Catholic Church dictated that painters in Italy (and the rest of Europe consequently) to paint the Virgin Mary with the new most expensive pigment imported from Asia – ultramarine – instead of the earlier sombre black, grey, violet, dark green or dark blue. Blue thus became associated with holiness, humility and virtue.
- King Louis IX of France, better known as Saint Louis (1214–1270), became the first king of France to regularly dress in blue. This was copied by other nobles. Paintings of the mythical King Arthur began to show him dressed in blue. The coat of arms of the kings of France became an azure or light blue shield, sprinkled with golden fleur-de-lis or lilies. Blue had come from obscurity to become the royal colour.
- Once blue became the colour of the king, it also became the colour of the wealthy and powerful in Europe. In the Middle Ages in France and to some extent in Italy, the dyeing of blue cloth was subject to license from the crown or state. In Italy, the dyeing of blue was assigned to a specific guild, the tintori di guado, and could not be done by anyone else without severe penalty. The wearing of blue implied some dignity and some wealth.
- artists tried to create harmonies between blue and red, lightening the blue with lead white paint and adding shadows and highlights. Raphael was a master of this technique, carefully balancing the reds and the blues so no one colour dominated the picture.
- Ultramarine was the most prestigious blue of the Renaissance, and patrons sometimes specified that it be used in paintings they commissioned.
- Often painters or clients saved money by using less expensive blues, such as azurite smalt, or pigments made with indigo, but this sometimes caused problems. Pigments made from azurite were less expensive, but tended to turn dark and green with time.
- Discovery of complementary colours, and use in painting shadows increased the demand for blues. Blue was a favourite colour of the impressionist painters, who used it not just to depict nature but to create moods, feelings and atmospheres.
- Van Gogh wrote to his brother Theo, “‘Cobalt [blue] is a divine colour and there is nothing so beautiful for putting atmosphere around things …” “The dark blue sky is spotted with clouds of an even darker blue than the fundamental blue of intense cobalt, and others of a lighter blue, like the bluish white of the Milky Way … the sea was very dark ultramarine, the shore a sort of violet and of light red as I see it, and on the dunes, a few bushes of prussian blue.”
20th and 21st century
At the beginning of the 20th century, many artists recognised the emotional power of blue, and made it the central element of paintings.
- During his Blue Period (1901–1904) Pablo Picasso used blue and green, with hardly any warm colours, to create a melancholy mood.
- In Russia, the symbolist painter Pavel Kuznetsov and the Blue Rose art group (1906–1908) used blue to create a fantastic and exotic atmosphere.
- In Germany, Wassily Kandinsky and other Russian émigrés formed the art group called Der Blaue Reiter (The Blue Rider), and used blue to symbolise spirituality and eternity.
- Henri Matisse used intense blues to express the emotions he wanted viewers to feel. Matisse wrote, “A certain blue penetrates your soul.”
- abstract expressionist movement began to use blue and other colours in pure form, without any attempt to represent anything, to inspire ideas and emotions. PainterMark Rothko observed that colour was “only an instrument;” his interest was “in expressing human emotions tragedy, ecstasy, doom, and so on.”
- In fashion blue, particularly dark blue, was seen as a colour which was serious but not grim. In the mid-20th century, blue passed black as the most common colour of men’s business suits, the costume usually worn by political and business leaders. In 1873 a German immigrant in San Francisco, Levi Strauss, invented a sturdy kind of work trousers, made of denim fabric and coloured with indigo dye, called blue jeans. In 1935, they were raised to the level of high fashion by Vogue magazine. Beginning in the 1950s, they became an essential part of uniform of young people in the United States, Europe, and around the world.
- Blue was also seen as a colour which was authoritative without being threatening. Following the Second World War, blue was adopted as the colour of important international organisations, including the United Nations, the Council of Europe, UNESCO, the European Union, and NATO. United Nations peacekeepers wear blue helmets to stress their peacekeeping role. Blue is used by the NATO Military Symbols for Land Based Systems to denote friendly forces, hence the term “blue on blue” for friendly fire, and Blue Force Tracking for location of friendly units. The People’s Liberation Army of China (formerly known as the “Red Army”) uses the term “Blue Army” to refer to hostile forces during exercises.
- The 20th century saw the invention of new ways of creating blue, such as chemiluminescence, making blue light through a chemical reaction.
- With the dawn of the World Wide Web, blue has become the standard colour for hyperlinks in graphic browsers (though in most browsers links turn purple if you visit their target), to make their presence within text obvious to readers.
- Blue is commonly used in the Western Hemisphere to symbolise boys, in contrast to pink used for girls. In the early 1900s, blue was the colour for girls, since it had traditionally been the colour of the Virgin Mary in Western Art, while pink was for boys (as it was akin to the colour red, considered a masculine colour).
- In the English language, blue often represents the human emotion of sadness, for example, “He was feeling blue”. It may also be in relation to rain, which is usually regarded as a trigger of depressive emotions.
- In German, to be “blue” (blau sein) is to be drunk. This derives from the ancient use of urine, particularly the urine of men who had been drinking alcohol in dyeing cloth blue with woad or indigo. A person who regularly looks upon the world with a blue eye is a person who is rather naive.
- Blue can sometimes represent happiness and optimism in popular songs, usually referring to blue skies.
Public opinion polls in the United States and Europe showed that blue was the favourite colour of over fifty per cent of respondents. Green was far behind with twenty per cent, while white and red received about eight per cent each.