Where Does That Pigment Come From? Quiz

Answer: Powdered iron oxide

Because limonite (which is the name for a range of compounds that are basically made from iron oxide) is very common, and the mineral is easily made into a paint by crushing the ore and mixing with water or oil, many cave paintings from the earliest times used it.

The colors depend on the exact chemical formula of the mineral, but they are usually yellow-brown if they have a lot of hydrated iron oxide (rust, to you and me). Red ochre has mostly anhydrous iron oxide.

Answer: Dried and powdered insects

The cochineal, a scale insect found in Central and South America, is the traditional source for carminic acid, which is then mixed with alum to produce the dye carmine. There are some other insects whose bodies yield carminic acid, too. The bright red color of carmine makes it attractive for use in paints (although now oil painters use synthetic reds that hold their color better over the years), fabric dyes, makeup and food coloring.

Answer: Mucus from a snail

Over 3000 years ago, the Phoenicians (whose capital was Tyre) learned to produce dye by poking Murex snails to make them produce their defensive mucus, and collecting it. This was a tedious process, so the resulting dye was very expensive. Since it held its color well (and even got brighter with time), it was still highly sought after. So valued was it that the color purple became associated with royalty, the only people who could really afford it.

Answer: Pulverised lapis lazuli

Like purple, blue was a very difficult color to produce in olden times, and the best bright blue came from grinding lapis lazuli into a powder. Most of the world's lapis lazuli comes from mines in Afghanistan and Pakistan, so when it appeared in Europe it had come a long way! Because ultramarine was so expensive, Renaissance painters used it sparingly, but it was commonly used to produce the blue in the robes of the Virgin Mary in their religious painting, or for some of the clothing in a portrait of a wealthy patron who could pay for the extravagance.

Answer: (Rumored) Cattle urine

Modern Indian yellow uses synthetic pigments, but the Dutch Masters who used it in their paintings because of its luminosity - its color intensified when exposed to light - used a pigment of unknown origins, which was imported from India in yellow balls for their use.

The author T. N. Mukharji wrote a letter describing how it was made by drying the urine of cattle that had been fed only on mango leaves, to collect the chemicals that were left behind. However, later chemical analysis suggests that it actually came from some plant source, although no definite origin has been identified.

Answer: Mixing ferrocyanide and iron (III) solutions

Prussian blue, the first modern synthetic pigment, was discovered by accident in 1704. Its value was immediately clear, as it produced a stable and vivid blue that was much less expensive that ultramarine had been. Its name comes from its use for the military uniforms of the Prussian army in the 18th and 19th centuries.

Answer: Chemically oxidising aniline

In 1856, William Henry Perkin was a student trying to make quinine, when one of his failed attempts showed a purple color as he was washing up. Further investigation led to the development of the first synthetic dye using organic (as opposed to mineral) chemicals. This discovery made purple (at least, in the pink-purple range) available to the masses, not just the wealthy.

Answer: Oxidation of copper

Statues made of copper (or brass or bronze, alloys that contain copper) will change color from brown to green over time, as their surface reacts with the air, and produces a layer of verdigris. Natural verdigris is often a mixture of several different copper (II) salts, depending on the environmental conditions to which the copper is exposed. To produce verdigris for use as a pigment, copper plates are reacted with acetic acid (originally, by hanging the copper over a vat of boiling vinegar) to produce the chemical copper (II) acetate.

Answer: Powdered cinnabar

Powdered cinnabar can be used to make a brilliant, bright orange-red color. This can have any of a range of shades, depending on how finely the mercury sulfide is ground - the smaller the crystals in the powder, the brighter and more orange the color. Coarse powder can be almost purple.

While vermilion was widely used in the ancient civilisations of China, India and Rome, and continued to be used through the Middle Ages for illuminated manuscripts and in the Renaissance for oil paintings, it is now rarely used because of the toxic nature of the mercury in it.

Answer: Mixing aniline with carbon tetrachloride

The discovery of mauveine led to a lot of other people investigating the production of aniline dyes, and François-Emmanuel Verguin patented his process for creating fuchsine in 1859. The chemical was originally named because its color resembled that of the fuchsia flower; its color was renamed later that year to magenta, in honor of a French victory in the Battle of Magenta.