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From Cave Paintings to M&Ms

Throughout the ages, humans have resorted to different minerals and chemicals to successfully produce various shades of the colour red. Why?

Studies have shown that red is the colour that attracts attention. Its uses are timeless and endless. Since ancient times, the colour red has been involved in fashion, art, food and cosmetics. But how was the colour red extracted or manufactured? Interestingly, throughout the ages, humans have resorted to different minerals and chemicals to successfully produce various shades of red.

The colour red made its debut in human culture thousands of years ago in pigments used in cave art. Red, black and white were the common colours used because they were readily available as natural pigments. Cave painters would use red ochre, iron oxide in chemical terms. A red dye could also be extracted from the roots of the madder plant that grows widely in Europe, Asia and Africa. The roots are dried and boiled in order to produce a brilliant ruby-red pigment. Madder was used as a textile dye in ancient Egypt, Greece and Rome. Later, many famous artists like Vermeer used madder lake in their paintings.

Red lead (lead tetroxide) was another pigment regularly used by the ancient Romans, Chinese, Persians and Indians. This pigment was prepared by roasting white lead carbonate. Although red lead is toxic, it has had many different applications. The ancient Chinese used red lead to colour silk fabrics and to treat ringworms and ulcerations. The Greeks, on the other hand, preferred to use the pigment for decorating temples and palaces. Its popularity continued during the Middle Ages with red lead being commonly used on illuminated manuscripts. Today red lead is not used due to its toxicity.

Perhaps, the most dangerous pigment was vermillion, made from cinnabar or mercury sulphide. Workers exposed to the toxic mercury fumes would suffer greatly. Working in cinnabar mines was often a death sentence, which explains why most miners were slaves or prisoners.

In the Americas, the colour red was extracted from tiny crushed cochineal insects. The Spaniards learned about these bugs when they conquered Mexico and Central America and imported them to Europe at very high prices. The female cochineal produces carminic acid to protect itself against predators. Once carminic acid is extracted from the insects, it is mixed with aluminium or calcium salts to produce a dye called carmine, widely used in the cosmetic and food industries. Carmine can be found in juices, ice cream, yogurt, candy, salami, lipstick, nail polish and eye shadow.

The biggest advance in dye production occurred in the latter part of the 19th century thanks to William Henry Perkin’s accidental discovery of mauve while trying to convert aniline from coal tar into quinine needed to treat malaria. Soon Perkin found a way to convert anthracene, another coal tar extract, into alizarin, the compound that gives madder its red colour. Since the synthetic version could be produced for the fraction of the cost of the natural, sales took off.

While today numerous dyes can be produced synthetically, concerns have arisen about their safety, particularly when used in foods. Over the years safety issues have resulted in the elimination of a number of dyes leaving those with a good safety record on the market. But some concerns, such as the possible triggering of behavioural problems in children still remain and many manufacturers are shifting to natural dyes extracted from beets, berries and various plants.

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