Cow urine, cuttlefish ink, and burned white lead were among the substances used as pigments throughout history.

Titanium white can be found in items ranging from paint to pills. Though it was created in New York in 1908, the pigment was first used hundreds of years earlier by the Inca, according to this article.

Lignum nephriticum, a tea used to treat kidney and urinary illnesses, was described in the 16th century as derived from white wood that turned water a bluish hue. However, in the 17th century, accounts described the wood as reddish and creating a kaleidoscope of colors in water. In 1915, the sources were identified as two different woods, which absorb UV radiation and emit visible light.

In 1856, a chemist accidentally discovered mauveine, the world's first synthetic dye, while trying to make quinine to treat malaria. The synthetic dyes that followed helped reveal germs under microscopes, paving the way for modern imaging techniques and breakthrough treatments, such as antibiotics.

Previously used to map the distribution of molecules on biological tissue samples, researchers combined the technique with machine learning to uncover six layers of pigments, binders, and a thin gold leaf layer within The Marriage of the Virgin, from a collection in the Metropolitan Museum of Art. The technique may help identify and track artists' material use to learn about pieces of unknown provenance.

With hundreds of ink manufacturers, all unregulated by the FDA, it’s hard to determine the exact ingredients in tattoo inks. Some pigments may contain carcinogenic chemicals, such as heavy metals and aromatic hydrocarbons, or even bacterial contaminants. Red ink often causes allergic reactions and may even contain lead or mercury.

When electrons are accelerated in the loop, they produce intense X-rays that can reveal properties of a sample struck by them, just as X-rays can be used to show bone structure in humans. Studying the reflected light from fossils can uncover the presence of known pigmentation compounds.

Soap has been produced since at least 2,200 BCE via a chemical reaction between fats or oils and a base. This creates salts that act as molecular bridges, helping water lift dirt and grease from surfaces. The same chemistry produces scum when metals in hard water bind to soap molecules, as well as white spots in paintings when metal ions in pigments react with fatty acids in the oil binder.

Archaeologists stumbling upon statues from ancient Greece often found weathered creatures, their faces and figures marred by age and conflict. But evidence of polychromy—painting sculptures with color—has continued to mount.

Love vanilla-flavored foods? Well, it was once made from castoreum - a yellowish exudate from the castor sacs of mature beavers. And the FDA regards castoreum as “natural flavoring."

Cave paintings long predate local craft stores and premade paints, so what techniques and tools did cave artists use to create such long-lasting works? This video gallery details how ancient artists inscribed and painted their work on cave walls, specifically the Chauvet cave in France.

Stomach acid and enzymes break down food into smaller particles, expelling a semi-fluid mass called chyme into the small intestine, where bile is added. As the intestines absorb nutrients and water, the chyme solidifies and changes color.

Lead was one of the earliest metals mined on Earth, desired for its soft malleability and used in cosmetics, pipework, gasoline, and more. But even though researchers demonstrated its toxicity in the 20th century, much of the world still uses it.

The red light originates from a long-lasting excited electron state in the element's atomic structure. The brittle gray metal has historically been used in pigment production, the manufacturing of rust-resistant stainless steel, and the creation of durable coatings with long-lasting shine for metals, wood, and leather.

As ancient artists made their way deep into caves and created massive works of art that continue to inspire awe today, they would've required light sources to see what they were doing. This gallery details some of the light sources that cave artists...

The tradition goes back to the 16th century, when the delicate canvases were hung in churches and cloisters. The difficulty in painting on the cobwebs was intended to illustrate one's devotion to their faith.

Besides the various salts and metals used to produce fireworks colors, shells are also filled with gunpowder and oxidizers to help fuel and accelerate reactions. Chlorates help strengthen colors, while dextrin, a starch, helps hold mixtures together.

One University of Colorado professor has developed an ink that can be "turned on" with exposure to UV light, and "turned off" with sunlight. While the ink could help those who want to hide their body art from family members or coworkers, there are potential uses for medical procedures.

After radium was discovered in 1898, companies began using radium-based paints on watch and clock dials to create a glow-in-the-dark effect. Women who worked to apply the paint were encouraged to use their lips and tongues to help create the fine point needed to draw small numbers, unknowingly poisoning themselves.

While some animals are sensitive to many forms of light, humans possess receptors that are sensitive to red, green, and blue wavelengths. These receptors send signals to the brain, which are processed and mixed to produce the array of colors we observe, including magenta, pink, and "supercolors" that lack a corresponding natural wavelength in the visible spectrum.

In 1896, Henri Becquerel had been exploring phosphorescence—the emission of light of one color after an object is exposed to another color. He expected these emissions to come from objects exposed to sunlight, but he observed emissions after an overcast day.

- Legendary artist Picasso (1881–1973)

Asphalt is derived from bitumen, a naturally occurring byproduct of decomposed organic materials. As one of the thickest forms of petroleum, the substance has been in use by humans and their ancestors for at least 40,000 years for various purposes, including as a sealant, an adhesive, decoration, and more. Learn more about this ancient material here.

The innate coloration comes from water absorbing red light in the visible spectrum more than green or blue, giving shallow waters in some parts of the Caribbean their turquoise hue. If sand is light, it can be churned up by turbulent water, clouding its appearance. Plankton and other organisms can color water by affecting how the rest of the spectrum is absorbed or reflected.

Crude oil processing produces a variety of fuels and the building blocks for plastics, but it also distills out the hydrocarbons used to make aspirin, Teflon, vinyl, crayons, candles, Tupperware, roofing shingles, asphalt pavement, hair dye, anesthetics, food-grade lubricants, polyester, synthetic rubber, and resins for items like dentures.