4: Materials and Process Colour


Sources: Wikipedia  Yellow

What is Yellow? Physics and Optics

Colours of yellow

Yellow is the colour between green and orange in the spectrum of visible light. It is the brightest and lightest of all colours. As the colour of sunlight, it is commonly associated with warmth, combined with red with heat and energy. A room painted yellow feels warmer than a room painted white, and a lamp with yellow light seems more natural than a lamp with white light. Yellow is the colour most associated with optimism and pleasure, gaiety and celebration.

Yellow is the most visible colour from a distance, so it is often used for objects that need to be seen, such as fire engines, road maintenance equipment, school buses and taxicabs. It is also often used for warning signs, since yellow traditionally signals caution, rather than danger. Safety yellow is often used for safety and accident prevention information. A yellow light on a traffic signal means slow down, but not stop. A yellow penalty card in a soccer match means warning, but not expulsion.

The darkest pure yellow is still brilliant compared with all other colours. Yellow is most intense against black, and most insipid against white. As it is usually found against darker tones, yellow often seems to radiate light in a picture. When it is seen against violet and blue it is strong.


Traditional yellows made from ochre, arsenic, cow urine, and other substances. These were replaced in the 18th and 19th century with synthetic pigments.

  •  Yellow ochre (also known as Mars yellow, Pigment yellow 42, 43), hydrated ferric oxide (Fe2O3.H2O), is a naturally occurring pigment found in clays in many parts of the world. It is non-toxic and has been used in painting since prehistoric times.
  • Indian yellow is a transparent, fluorescent pigment used in oil paintings and watercolors. Originally magnesium euxanthate, it was claimed to have been produced from the urine of Indian cows fed only on mango leaves. It has now been replaced by synthetic Indian yellow hue.
  • Naples Yellow (lead antimonate yellow) is one of the oldest synthetic pigments, derived from the mineral bind heimite and used extensively up to the 20th century. It is toxic and nowadays is replaced in paint by a mixture of modern pigments.
  • Cadmium Yellow (cadmium sulfide, CdS) has been used in artists’ paints since the mid-19th century. Because of its toxicity, it may nowadays be replaced by azo pigments.
  • Chrome Yellow (lead chromate, PbCrO4), derived from the mineral crocoite, was used by artists in the earlier part of the 19th century, but has been largely replaced by other yellow pigments because of the toxicity of lead.
  • Zinc yellow or zinc chromate is a synthetic pigment made in the 19th century, and used by the painter Georges Seurat in his pointillist paintings. He did not know that it was highly unstable, and would quickly turn brown.
  • Titanium Yellow (nickel antimony titanium yellow rutile, NiO.Sb2O5.20TiO
    ) is created by adding small amounts of the oxides of nickel and antimony to titanium dioxide and heating. It is used to produce yellow paints with good white coverage and has the LBNL paint code “Y10”.
  • Gamboge is an orange-brown resin, derived from trees of the genus Garcinia, which becomes yellow when powdered. It was used as a watercolor pigment in the far east from the 8th century – the name “gamboge” is derived from “Cambodia” – and has been used in Europe since the 17th century.
  • Orpiment, also called King’s Yellow or Chinese Yellow is arsenic trisulfide (As
    ) and was used as a paint pigment until the 19th century when, because of its high toxicity and reaction with lead-based pigments, it was generally replaced by Cadmium Yellow.
  • Azo-dye based pigment (a brightly coloured transparent or semitransparent dye with a white pigment) is used as the colourant in most modern paints requiring either a highly saturated yellow or simplicity of colour mixing. The most common is the monoazo arylide yellow family, first marketed as Hansa Yellow.


According to surveys in Europe, Canada and the United States, yellow is the colour people most often associate with amusement, gentleness, and spontaneity, but also with duplicity, envy, jealousy, avarice, and, in the U.S., with cowardice. It plays an important role in Asian culture, particularly in China, where it is seen as the colour of happiness, glory, wisdom, virtue, nobility, harmony and culture.


The yellow color of gold symbolizes wisdom.


Yellow has strong historical and cultural associations as the colour of happiness, glory, and wisdom.

  • In the five directions of the compass, yellow signifies the middle or China. The Chinese Emperor was literally considered the child of heaven, with both a political and religious role, both symbolized by yellow. Only members of the Imperial household were permitted to wear yellow. The legendary first emperor of China was called the Yellow Emperor. The last emperor of China, Puyi (1906–67), described in his memoirs how every object which surrounded him as a child was yellow. “It made me understand from my most tender age that I was of a unique essence, and it instilled in me the consciousness of my “celestial nature” which made me different from every other human.” Distinguished visitors were honoured with a yellow, not a red, carpet.
  • the masculine yang is traditionally represented by yellow.
  • of the five Chinese seasons, the end of summer, symbolized by yellow leaves.
  • The term “yellow movie” (黃色電影) can refer to films of pornographic nature in Chinese culture, and is analogous to the English “blue movie”.


  • Yellow in Hinduism is considered sacred colour denoting valor, sacrifice and purity.
  • Buddhist monks wear saffron yellow robes.

Latin America

  • The ancient Maya associated the colour yellow with the direction South.
  • The Maya glyph for “yellow” (k’an) also means “precious” or “ripe”. Colour for corn???

Western traditions

“Now we are having beautiful warm, windless weather that is very beneficial to me. The sun, a light that for lack of a better word I can only call yellow, bright sulfur yellow, pale lemon gold. How beautiful yellow is!” Van Gogh letter to sister 1888

Yellow images by Van Gogh

Mickey Dugan Yellow Kid , New York newspaper colour comic strip. It took advantage of a new colour printing process, which used colour separation and three different colours of ink; magenta, cyan, and yellow, plus black, to create all the colours on the page.
Fragonard: A Young Girl Reading Circa 1776. Here yellow gives a sense of sunny calm and peaceful happiness.
The weather project, by Danish-Icelandic artist Olafur Eliasson, Turbine Hall of London’s Tate Modern in 2003. Eliasson used humidifiers to create a fine mist in the air via a mixture of sugar and water, as well as a semi-circular disc made up of hundreds of monochromatic lamps which radiated yellow light. The ceiling of the hall was covered with a huge mirror, in which visitors could see themselves as tiny black shadows against a mass of light.

The English word yellow comes from the Old English geolu, geolwe (oblique case), meaning “yellow, yellowish”, derived from the Proto-Germanic word gelwaz “yellow”. It has the same Indo-European base, gʰel-, as the words gold and yell; gʰel- means both bright and gleaming, and to cry out. Yellow is a color which cries out for attention.

In the west, yellow is not a well-loved colour; in a 2000 survey, only six percent of respondents in Europe and America named it as their favourite colour, compared with seven percent naming yellow as their least favourite colour.  Yellow is the colour of ambivalence and contradiction; the colour associated with optimism and amusement; but also with betrayal, duplicity, and jealousy.

As the color of light, yellow is also associated with knowledge and wisdom. In English and many other languages, “brilliant” and “bright” mean intelligent. In medieval European symbolism, red symbolized passion, blue symbolized the spiritual, and yellow symbolized reason. In many European universities, yellow gowns and caps are worn by members of the faculty of physical and natural sciences, as yellow is the color of reason and research.

  • Prehistory and antiquity: Yellow, in the form of yellow ochre pigment made from clay, was one of the first colours used in prehistoric cave art. The cave of Lascaux has an image of a horse coloured with yellow estimated to be 17,300 years old.
  • Ancient Egypt:  yellow+blue was associated with gold, which was considered to be imperishable, eternal and indestructible. The skin and bones of the gods were believed to be made of gold. The Egyptians used yellow extensively in tomb paintings; they usually used either yellow ochre or the brilliant orpiment, though it was made of arsenic and was highly toxic. A small paintbox with orpiment pigment was found in the tomb of King Tutankhamun. Men were always shown with brown faces, women with yellow ochre or gold faces.
  • Ancient Greece: some gods were depicted with yellow hair, and men commonly bleached their hair or spent hours in the sun to turn it yellow.
  • Romans used yellow in their paintings to represent gold and also in skin tones. It is found frequently in the murals of Pompeii. The word for ‘gold’ in Latin is aurum, which means yellow. However, in medieval Europe and later, the word yellow often had negative connotations; so yellow hair was more poetically called ‘blond,’ ‘light’, ‘fair,’ or especially ‘golden.’
  • Middle Ages and Renaissance: yellow became firmly established as the colour of Judas Iscariot, and also took on associations with envy, jealousy and duplicity.
  • Renaissance non-Christian outsiders, such as Jews, came to be marked with the colour yellow. In 16th century Spain, those accused of heresy and who refused to renounce their views were compelled to come before the Spanish Inquisition dressed in a yellow cape.
  • 18th and 19th centuries discovery and manufacture of synthetic pigments.  Jean-Honoré Fragonard painted A Young Girl Reading.  J.M.W. Turner Rain, Steam, and Speed – the Great Central Railway was dominated by glowing yellow clouds. Georges Seurat use the new synthetic yellows in his pointillist paintings but zinc yellow or zinc chromate, which he used in the light green lawns, was highly unstable and would quickly turn brown. Van Gogh used the traditional yellow ochre, but also chrome yellow, first made in 1809, and cadmium yellow, first made in 1820. At the end of the 19th century, Mickey Dugen’s Yellow Kid,  gave his name (and color) to the whole genre of popular, sensational journalism, which became known as “yellow journalism”.
  • 20th and 21st centuries: yellow was revived as a symbol of exclusion. Jews in Nazi Germany and German-occupied countries were required to sew yellow triangles with the star of David onto their clothing. Piet Mondrian made a series of paintings which consisted of a pure white canvas with grid of vertical and horizontal black lines and rectangles of yellow, red, and blue. Yellow often replaced red as the color of fire trucks and other emergency vehicles, and was popular in neon signs. Yellow” (“giallo“), in Italy, refers to crime stories, both fictional and real. This association began in about 1930, when the first series of crime novels published in Italy had yellow covers.


(from Wikipedia)


(from Wikipedia)

  • In the United States, a yellow dog Democrat was a Southern voter who consistently voted for Democratic candidates in the late 19th and early 20th centuries because of lingering resentment against the Republicans dating back to the Civil War and Reconstruction period. Today the term refers to a hard-core Democrat, supposedly referring to a person who would vote for a “yellow dog” before voting for a Republican.
  • In China the Yellow Turbans were a Daoist sect that staged an extensive rebellion during the Han Dynasty.
  • Yellow is an important color of anarcho-capitalist symbolism.
  • The 1986 People Power Revolution in the Philippines was also known as the Yellow Revolution due to the presence of yellow ribbons during the demonstrations.
  • Contemporary political parties using yellow include the Liberal Democrats and UKIP in the UK, SNP in Scotland and PUP in Australia.