There’s a rare collection tucked away in the Harvard Art Museums–but not of art. It’s the Forbes Pigment Collection, a vault of more than 2,500 pigments from across the world that chemists and historians use to learn more about how artists have used materials through the centuries.
Now, the bits of eye-popping color stored in glass vials are getting their own encyclopedia. An Atlas of Rare and Familiar Color documents the history of the collection and of color itself. Each chapter, devoted to a different color of the rainbow, consists of an essay on that color’s history along with beauty shots of each pigment.
Narayan Khandekar, a senior conservation scientist who directs Harvard’s art conservation program and curates the pigment collection, uses the pigments to do scientific analysis of paintings to determine how to restore them–or to test if they’re fakes. For instance, Khandekar has tested a series of paintings that might have been painted by Jackson Pollock, but it turned out that the red pigment used was discovered in the 1970s–decades after Pollock’s death.
Pigments also tell some great stories. Here are seven of the most mind-boggling pigments in the collection.
Yellow Made From Cow Pee
The story goes that people in the village of Mirzapur in Bihar, India, would feed their cows mango leaves, and then collect their bright yellow urine and turn it into a dye. The dye was sold in golf ball-sized spheres–some of which are now in the collection at Harvard. But the story might be a myth; there’s only one eyewitness account from 1883 describing exactly how the pigment was made. To learn more, the art historian Victoria Finlay traveled to Mirzapur in 2001. There was no yellow dye made in the village by that point, and in the book Findlay describes how “people laughed until they wept at the very idea of making cows urinate to create color.”
But it is possible–Finlay also noticed a mango orchard where buffalo grazed, and Khandekar’s father, who grew up in India, says that mango trees used to grow wild, everywhere, making it conceivable that people noticed how eating the leaves turned cud-chewers’ pee bright yellow. A more recent chemical analysis also shows that there are animal and plant metabolites in the pigment, adding more scientific evidence. But it remains hard to say what parts of the story are myth and which are fact. “It seems like the truth is in the middle there somewhere,” Khandekar says.
A Blue More Expensive Than Gold
Ultramarine blue was a marker of social status. Mined in northeastern Afghanistan in the 14th and 15th centuries, it had to be brought down from the mountains on the backs of donkeys, then transported by ship to its final destination. It was so hard to get ahold of that it became incredibly expensive–even costlier than gold. Khandekar says that people who wanted to show off their piety (and maybe also their deep pockets) would request its use on altarpieces; the color was so expensive that it had to be a separate line item on the bill for the painting.
To extend their stores of the valuable pigment, artists would sometimes paint the Virgin’s mantle with azurite, a cheaper substance, and then cover it with a very thin layer of ultramarine. Others would mix in azurite or blue glass to extend their stores–and hope patrons with a discerning eye wouldn’t notice.
The ultramarine market finally crashed in 1826, when a chemist discovered a synthetic version, making the brilliant blue color much more widely available.
12,000 Mollusks Gave Their Lives for 1.4 Grams Of This Purple
Purple is another mythic color–it was supposedly discovered when the Greek hero Hercules’s dog was eating mollusks on the beach and came running back to his master with a bright purple snout. That’s how Tyrian purple is made, squeezing a creamy liquid out of a specific gland in the murex mollusk, which then turns red and then purple when exposed to the sun. Like ultramarine, it was frighteningly expensive, with 12,000 mollusks harvested to created 1.4 grams of the substance. That didn’t stop the power hungry of the ancient world who insisted on wearing their influence on their sleeves: In ancient Rome, senators had their togas dyed purple to show off their wealth. It all changed in 1856 when a chemist derived the pigment mauve out of the far cheaper coal tar, and Tyrian purple effectively met its end.
Revenge Of The Mummy Brown
Khandekar says that people used to obsessively try to recreate the beautiful, rich brown that old masters like Rembrandt and Titian used in their paintings. This led to all kinds of experiments with color, one of which made it into the history books: crushing mummies to make pigment. That’s right, mummy brown is literally made of mummified humans.
“These bodies were very disrespected,” Khandekar says, nodding to the fact that old mummies’ bodies were used in myriad ways, like turning the old linen into paper or even burning the bodies for fuel. But when it came to mummy brown pigment, there was a mystical element to it as well: “You’re taking something magical from another society and incorporating it into your work of art,” he says.
As far as art chemists know, no paintings have been identified that used mummy brown–there are only stories and samples, like the one in the collection. Now, Khandekar and his team are examining a painting by Juan Pantoja de la Cruz, a Spanish court painter before Diego Velazquez, who claimed to use mummy brown in his journals. They’ll look for chemical flags, like the presence of natural asphalt to determine if he did indeed use mummies.
Cochineal Red: A Prized Commodity Of The Spanish Empire
In medieval Europe, red was derived from female scale insects that lived on the Kermis oak tree in the Mediterranean. Called kermes red, it was difficult to obtain, so red wasn’t used frequently as a color. But when the Spanish colonized the new world, they discovered that the natives used a different beetle to crush into red pigment: the cochineal, which lives on nopal cactuses. It’s these bugs that provide the red color used in most Latin American textiles, and the Aztecs would actively cultivate and harvest the bugs–people even paid the Aztec rulers tribute in cochineal.
But it wasn’t just pretty to look at. After conquering Latin America, cochineal brought the Spanish Empire enormous wealth–it was the second most profitable commodity for the empire after silver. Today, Peru exports more cochineal than it did when the Spanish Empire ruled. It’s used the world over to color lipstick, red velvet cake, and even Strawberry Frappuccinos.
From Lab To Crayon
The collection also features modern colors like YInMn Blue, which was discovered by the Oregon State University professor Mas Subramanian in 2009. It’s the first synthetic inorganic blue pigment–meaning it’s manmade, out of compounds that don’t include carbon, oxygen, or nitrogen–since cobalt was discovered in 1802.
“It was serendipity, or a happy accident, because we weren’t looking for it,” Subramanian told me last year. “Most of the science discoveries come from an unexpected place.” Now, Crayola is making YInMn Blue into a crayon called “Bluetiful.”
A Toxic Yellow In Your Lego
Not all pigments are good to have around the house. Khandekar says that Lego used the cadmium pigment in its building blocks until the 1970s, and the pigment was popular in many other yellow-colored children’s toys including Barbies and My Little Pony dolls. Emerald green, made of copper and arsenic, was used in wallpaper, and toxic lead white found its way into toys and paint. Toxic materials around the house is still a problem; a recent study showed that secondhand toys, likely from earlier eras with less stringent standards, can have traces of cadmium, arsenic, lead, and more harmful chemicals.
Using toxic pigments has roots dating back to the ancient world, where cinnabar–a red pigment made from mercury–was used as a cosmetic. During the Roman era and the British empire, women used lead white as a kind of foundation, covering their faces with it (the lead would eventual discolor their skin, cause their hair to fall out, and discolor their teeth).