The Bizarre Link Between van Gogh's Signature Yellow and Cow Urine

Post-impressionist painter Vincent Van Gogh is known for his use of bold color, especially yellow. In one of his most famous works, "The Starry Night," (1889) a bright yellow moon breaks through the swirling night sky where it is joined by many stars. To achieve the special lunar hue, Van Gogh chose a popular pigment just years before it was deemed illegal and pulled from the market.

This special hue, Indian yellow, had also appeared in the works of several other well-known artists, thanks to its striking appearance and rich luminosity. But it was tinged with ethical issues that ultimately led to its downfall.

"I recall early on being very taken with the richness of that pigment and therefore paint," states Frank Piatek, professor of painting and drawing at the School of the Art Institute of Chicago, in an email. "But I was very disheartened when I had reason to look up the pigment in Ralph Mayer's compendium on artist's materials. In that text he cautioned against using that pigment as it may be prone to fading in sunlight, but also because of its curious form of manufacture."

And it was precisely that manufacturing process that shifted the status of the previously appreciated color.

Origins of Indian Yellow

The bright yellow hue took its English name from its place of origin. It was used as early as the 15th century in India, where it was called "piuri, purree or gogilī" according to paint manufacturer Winsor & Newton. At that time, it was employed for painting artworks, as well as walls and for dyeing cloth.

Reportedly imported to Europe between the 15th and 18th centuries, Indian yellow came in the form of "rather pungent balls," according to art supply purveyor Royal Talens. A yellow powder inside the balls only needed to be mixed with a binding agent to create the "golden yellow, transparent paint."

The list of artists who used it reads like a who's who of the period.

Indian yellow is found in Johannes Vermeer's "Woman Holding a Balance" (1662-3) – note the bright yellow-orange curtain. Joseph Mallord William Turner's "The Angel Standing in the Sun" (1846) gained its golden hue from Indian yellow, and it may have been used much earlier by Joshua Reynolds in his "The Age of Innocence" (1788), writes Kelly Grovier for BBC.

Grovier also notes that a mix of Indian yellow and other pigments helped John Singer Sargent achieve the "glowing charm" of lit lanterns against the "crepuscular half-light of dusk" in his "Carnation, Lily, Lily, Rose" (1885-86).

The Outlawing of Indian Yellow

So, what happened that caused this uniquely useful pigment to lose status?

By the late 19th century, there had been rumors that the unusual hue was the result of unappealing input from the urine of snakes or perhaps dehydrated camels. A botanist from the Royal Botanic Gardens, Kew decided to find out whether any of these ideas might be true and contacted the Indian Department of Revenue and Agriculture.

In 1883, the reply from public servant Trailokya Nath (T.N.) Mukharji attested that he had seen cows in Mirzapur, Bengal, fed a diet of only mango leaves. This restricted intake created a condition of dehydration, leading to intense yellow urine, which was collected and processed into the powder that was exported to Europe in those yellow pigment balls. In addition to being purposefully dehydrated, the cows ingested a toxin found in the mango leaves, thus they appeared altogether unhealthy, according to Mukharji.

Despite Mukharji's report, other theories about the nature of Indian yellow circulated. For example, in 1886, Scottish chemist John Stenhouse asserted it was made from plant sap. Nevertheless, within a few decades of Mukharji's explanation, the making of Indian yellow was outlawed in Bengal and no longer used in Europe, explains Grovier. According to Royal Talens: "As not all the pigment was excreted, the animals developed large kidney stones which made passing urine very painful. This often led to them kicking over the buckets full of expensive urine, so rigorous measures were introduced such as the animals being suspended with leather straps. It was even claimed that the cows only passed urine when massaged in the genital area. Due to the holy status of the cow this production was banned in 1908."

In 2019, researchers published the results of a test they had run on some remaining balls of the original Indian yellow pigment, identifying the presence of hippuric acid, "a ruminant metabolite found in urine." The researchers concluded: "the examination of authentic relics in the Economic Botany Collection at the Royal Botanic Gardens, Kew from T.N. Mukharji's investigation of Indian yellow supports the veracity of his report regarding the manufacture of Indian yellow."

Indian Yellow Today

Just as modern chemistry was able to discern the chemical nature of the original Indian yellow pigment, chemistry has made it possible to keep the best part of the hue on the palette. For example, since 1996, Winsor & Newton has offered a synthetic replacement made of nickel azo, hansa yellow and quinacridone burnt orange, available in its oil and watercolor ranges.

Piatek explains that often traditional names are used for a new version of a color created through synthetic chemistry. Particularly in the case of Indian yellow, the result is a positive outcome for humans and cows alike.

"As of now there are a number of rich, transparent yellow-orange pigments/paints," he says. "The name Indian yellow is apt for the paint available to painters in the present."