Orpiment

What color is orpiment?

The story of orpiment

Orpiment means gold pigment, which tells you what the Romans hoped it was. What it is, is arsenic.

The mineral is arsenic trisulfide from hot springs and volcanic vents. Lumps of it were found in an Egyptian tomb from the 1300s BC; it is on Tutankhamun's walls. Theophrastus called it arsenikon in the fourth century BC, from the Greek for male, because the Greeks thought metals had sexes; Pliny called it auripigmentum and believed it held gold. Its twin is realgar, orange-red, from the same veins; the name is Arabic for powder of the mine. Greek apothecaries sold realgar as a medicine called bull's blood, and the physician Nicander described a death from it that matches arsenic poisoning.

China named them as a pair: ci huang, female yellow, for orpiment, and xiong huang, male yellow, for realgar. Orpiment colored lacquer, and alchemists in China and Europe took an interest: a golden mineral looked like a shortcut to gold. Realgar had a festival. At the Dragon Boat Festival adults drank rice wine dosed with realgar powder, and children had the character for king painted on their foreheads with the leftover slurry, against snakes and evil spirits. Modern tests of that wine found 70 to 400 milligrams of dissolved arsenic per liter. Orpiment is on the walls of the Taj Mahal too.

Medieval Europe imported it from Asia Minor for altar frontals and icons. Mixed with indigo it made a deep green: Edmund the Martyr's cloak in the Wilton Diptych, painted for Richard II in the 1390s, is orpiment and indigo. Raphael used it for the yellows of the Sistine Madonna. Venice was its capital. Titian used both realgar and orpiment; Tintoretto used orpiment for the gold embroidery on Vincenzo Morosini's stole and the highlights on his ferret, around 1575 to 1580. Realgar as a paint was a Venetian habit, rare elsewhere in Europe, and gone by the 1700s.

Everything about it was trouble. It was fly poison, arrow poison and rat poison, and it stripped hair from people and hides alike. It quarreled with lead and copper pigments such as verdigris and azurite. It fell apart in light, and a 2016 study found the arsenic it shed seeping through every paint layer around it. So when chrome yellow arrived around 1810, and then cadmium yellow, from a metal discovered in 1817 and on sale by the 1840s, painters dropped it. Arsenic's other famous color, the copper green sold as emerald green from 1814, is a story of its own.

Nobody puts orpiment or realgar into paint now. If a tube says orpiment it is a hue; read the pigment code. The mineral still turns up: in 2023 Britain's product safety office recalled forty orpiment bookends a discount chain had been selling. The poisonous colors were mostly the bright ones, because bright is hard, and chemistry that does something dramatic to light tends to do something dramatic to you. For three thousand years this was one of the few clean yellows there were, and every painter who used it had to remember not to lick the brush. A modern yellow does the job with no body count. I am fine with progress.

Pigment facts

These describe the pigment in general. Every brand's tube behaves a little differently, so test yours on scrap paper.

How to mix orpiment

You cannot mix an arsenic mineral, and you would not want to. The color is easy: start with a warm lemon yellow and add the smallest touch of orange until it reads as gold rather than lemon. That is orpiment. Keep going toward a warm red and you reach realgar's orange.

One pairing matters more than the rest, and it is the medieval one: yellow and indigo. Orpiment mixed with indigo gave painters a deep, cool leaf green six hundred years ago, and the recipe works with any warm yellow. Two parts yellow to one of indigo, thinned well.

Using orpiment in watercolor

Use the hue for anything meant to look like gold: embroidery, brass, halos, the rim of a cup. Put a shadow of burnt sienna beside a warm yellow and it reads as metal at once.

Paint it the way manuscript painters did, in flat, even coats rather than one heavy one. Two thin layers of a warm yellow, each left to dry, give a cleaner color than one thick layer.

It pairs with its opposite. Indigo or a violet beside it makes the yellow look brighter, and indigo mixed into it makes the medieval green. Next to a bright red it turns orange in your eye, which is realgar's job.

Two warnings, one I learned the hard way and one I did not have to. Warm yellows go green the instant they touch a blue-black in a wet wash. And if you buy old paints at a flea market, read the labels: orpiment, King's yellow or realgar means a sealed bag, not your palette.

Orpiment vs realgar (and cadmium yellow)

Realgar and orpiment are the same two elements, arsenic and sulfur, in different proportions, and they grow in the same veins. Orpiment is the yellow, As2S3; realgar is the orange-red, As4S4, and after years in the light it turns into a yellow powder called pararealgar, so the two blur into each other on old walls.

Cadmium yellow is the pigment that finished orpiment off. It arrived commercially in the 1840s and it holds its color. It is another heavy metal, not something to eat or breathe as dust, but in a tube it stays put, which arsenic never did.

If orpiment is a gold coin, realgar is the same coin held up to the fire, and cadmium yellow is the photograph of it you can safely hang on the wall.

More color stories

Mel, founder of Tobio'sI make portable watercolor kits and I named the company after my cat. I write these pages for the beginner I used to be, one pigment at a time.