Orange is the colour between yellow and red on the spectrum of visible light. Human eyes perceive orange when observing light with a dominant wavelength between roughly 585 and 620 nanometres. In painting and traditional colour theory, it is a secondary colour of pigments, created by mixing yellow and red. It is named after the fruit of the same name.

The orange colour of carrots, pumpkins, sweet potatoes, oranges, and many other fruits and vegetables comes from carotenes, a type of photosynthetic pigment. These pigments convert the light energy that the plants absorb from the sun into chemical energy for the plants’ growth. Similarly the hues of autumn leaves are from the same pigment after chlorophyll is removed.

In Europe and America, surveys show that orange is the colour most associated with amusement, the unconventional, extroverts, warmth, fire, energy, activity, danger, taste and aroma, Protestantism, the autumn and Allhallowtide seasons, as well as having long been the national colour of the Netherlands and the House of Orange. It also serves as the political colour of Christian democracy political ideology and most Christian democratic political parties. In Asia it is an important symbolic colour of Buddhism and Hinduism.

History and art
In ancient Egypt artists used an orange mineral pigment called realgar for tomb paintings, as well as other uses. It was also used later by Medieval artists for the colouring of manuscripts. Pigments were also made in ancient times from a mineral known as orpiment. Orpiment was an important item of trade in the Roman Empire and was used as a medicine in China although it contains arsenic and is highly toxic. It was also used as a fly poison and to poison arrows. Because of its yellow-orange colour, it was also a favourite with alchemists searching for a way to make gold, in both China and the West.

Before the late 15th century, the colour orange existed in Europe, but without the name; it was simply called yellow-red. Portuguese merchants brought the first orange trees to Europe from Asia in the late 15th and early 16th century, along with the Sanskrit naranga, which gradually became part of several European languages: “naranja” in Spanish, “laranja” in Portuguese, and “orange” in English.

House of Orange
The House of Orange-Nassau was one of the most influential royal houses in Europe in the 16th and 17th centuries. It originated in 1163 the tiny Principality of Orange, a feudal state of 108 square miles (280 km2) north of Avignon in southern France. The Principality of Orange took its name not from the fruit, but from a Roman-Celtic settlement on the site which was founded in 36 or 35 BC and was named Arausio, after a Celtic water god; however, the name may have been slightly altered, and the town associated with the colour, because it was on the route by which quantities of oranges were brought from southern ports such as Marseilles to northern France.

The family of the Prince of Orange eventually adopted the name and the colour orange. The colour came to be associated with Protestantism, due to participation by the House of Orange on the Protestant side in the French Wars of Religion. One member of the house, William I of Orange, organised the Dutch resistance against Spain, a war that lasted for eighty years, until the Netherlands won its independence. Another member, William III of Orange, became King of England in 1689, after the downfall of the Catholic James II.

Due to William III, orange became an important political colour in Britain and Europe. William was a Protestant, and as such he defended the Protestant minority of Ireland against the majority Roman Catholic population. As a result, the Protestants of Ireland were known as Orangemen. Orange eventually became one of the colours of the Irish flag, symbolising the Protestant heritage.

When the Dutch settlers of South Africa rebelled against the British in the late 19th century, they organised what they called the Orange Free State. In the United States, the flag of the City of New York has an orange stripe, to remember the Dutch colonists who founded the city. William of Orange is also remembered as the founder of the College of William & Mary, and Nassau County in New York is named after the House of Orange-Nassau.

18th and 19th century
In the 18th century orange was sometimes used to depict the robes of Pomona, the goddess of fruitful abundance; her name came from the pomon, the Latin word for fruit. Oranges themselves became more common in northern Europe, thanks to the 17th century invention of the heated greenhouse, a building type which became known as an orangerie. The French artist Jean-Honoré Fragonard depicted an allegorical figure of “inspiration” dressed in orange.

In 1797 a French scientist Louis Vauquelin discovered the mineral crocoite, or lead chromate, which led in 1809 to the invention of the synthetic pigment chrome orange. Other synthetic pigments, cobalt red, cobalt yellow, and cobalt orange, the last made from cadmium sulfide plus cadmium selenide, soon followed. These new pigments, plus the invention of the metal paint tube in 1841, made it possible for artists to paint outdoors and to capture the colours of natural light.

In Britain orange became highly popular with the Pre-Raphaelites and with history painters. The flowing red-orange hair of Elizabeth Siddal, the wife of painter Dante Gabriel Rossetti, became a symbol of the Pre-Raphaelite movement, Lord Leighton, the president of the Royal Academy, produced Flaming June, a painting of a sleeping young woman in a bright orange dress, which won wide acclaim. Albert Joseph Moore painted festive scenes of Romans wearing orange cloaks brighter than any the Romans ever likely wore. In the United States, Winslow Homer brightened his palette with vivid oranges.

In France painters took orange in an entirely different direction. In 1872 Claude Monet painted Impression Sunrise, a tiny orange sun and some orange light reflected on the clouds and water in the centre of a hazy blue landscape. This painting gave its name to the impressionist movement.

Orange became an important colour for all the impressionist painters. They all had studied the recent books on colour theory, and they know that orange placed next to azure blue made both colours much brighter. Auguste Renoir painted boats with stripes of chrome orange paint straight from the tube. Paul Cézanne did not use orange pigment, but created his own oranges with touches of yellow, red and ochre against a blue background. Toulouse-Lautrec often used oranges in the skirts of dancers and gowns of Parisiennes in the cafes and clubs he portrayed. For him it was the colour of festivity and amusement.

The post-impressionists went even further with orange. Paul Gauguin used oranges as backgrounds, for clothing and skin colour, to fill his pictures with light and exoticism. But no other painter used orange so often and dramatically as Vincent van Gogh. who had shared a house with Gauguin in Arles for a time. For Van Gogh orange and yellow were the pure sunlight of Provence. He created his own oranges with mixtures of yellow, ochre and red, and placed them next to slashes of sienna red and bottle green, and below a sky of turbulent blue and violet. He put an orange moon and stars in a cobalt blue sky. He wrote to his brother Theo of “searching for oppositions of blue with orange, of red with green, of yellow with violet, searching for broken colours and neutral colours to harmonize the brutality of extremes, trying to make the colours intense, and not a harmony of greys.”

20th and 21st centuries
In the 20th and 21st centuries, the colour orange had highly varied associations, both positive and negative.

The high visibility of orange made it a popular colour for certain kinds of clothing and equipment. During the Second World War, US Navy pilots in the Pacific began to wear orange inflatable life jackets, which could be spotted by search and rescue planes. After the war, these jackets became common on both civilian and naval vessels of all sizes, and on aircraft that flew over water. Orange was also widely worn by workers on highways and by cyclists to avoid being hit

A herbicide called Agent Orange was widely sprayed from aircraft by the Royal Air Force during the Malayan Emergency and the US Air Force during the Vietnam War to remove the forest and jungle cover beneath which enemy combatants were believed to be hiding, and to expose their supply routes. The chemical was not actually orange, but took its name from the colour of the steel drums in which it was stored. Agent Orange was toxic, and was later linked to birth defects and other health problems.

Orange also had and continues to have a political dimension. Orange serves as the colour of Christian democratic political ideology, which is based on Catholic social teaching and Neo-Calvinist theology; Christian democratic political parties came to prominence in Europe and the Americas after World War II.

In Ukraine in November–December 2004, it became the colour of the Orange Revolution, a popular movement which carried activist and reformer Viktor Yushchenko into the presidency. In parts of the world, especially Northern Ireland, the color is associated with the Orange Order, a Protestant fraternal organisation and relatedly, Orangemen, marches and other social and political activities, with the color orange being associated with Protestantism similar to the Netherlands.

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