Indian Yellow

What color is Indian yellow?

The story of Indian yellow

Indian yellow glowed like late sunlight and smelled like a cowshed, and the two facts turned out to be related.

It came out of India as hard, dirty yellow balls called purree, or piuri, deep orange inside. Washed and ground, they gave a transparent yellow that Mughal and Rajput painters used from the 1500s and that Europe was buying by the 1800s. Its trick is glow: the color fluoresces a little, so a thin wash looks brighter in sunlight than it has any right to, which is why Turner liked it. Tate's conservators have found Indian yellow in his watercolors, a Norham Castle study of about 1798 among them, with a warning attached: alongside gamboge and the yellow lakes it faded even faster than indigo, which is why so many old watercolor landscapes now look bluer than they were painted.

What it was made of was a long argument. In 1844 the chemist John Stenhouse cut open a ball of purree, noted a smell like castor oil and a mass of needle-shaped crystals, and decided it was boiled-down plant juice. Then came a letter dated 27 August 1883 from T. N. Mukharji, a Calcutta civil servant, written because Sir Joseph Hooker at Kew had asked. Mukharji went to Monghyr in Bihar and found a few milkmen in a suburb called Mirzapur who fed their cows nothing but mango leaves and water. The cows looked ill. Each gave about three quarts of bright yellow urine a day, which was heated in earthen pots until the yellow dropped out, strained through cloth, rolled into balls and dried on charcoal and then in the sun. Three quarts made two ounces. He watched it all and sent Hooker the pigment, a bottle of the urine, an earthen pot and a bundle of mango leaves.

The usual ending is that the trade was declared cruel and banned in 1908, and the color was gone from the catalogs by about 1921. In 2002 the writer Victoria Finlay went to look. She found no record of any such law, nobody in Mirzapur who remembered making the stuff, and no printed witness apart from Mukharji's single letter. It began to look like a colonial tall tale. It was not, or not entirely: studies in 2017 and 2018 reopened the sample Mukharji had sent to Kew and found hippuric acid, a marker for urine, alongside the euxanthic acid that carries the color. The urine is real. The ban may be a legend.

Today's tube has no cow in it. Modern Indian yellow is a hue, and the label tells you which: usually a nickel azo yellow, PY150, which conservators call artificial Indian yellow because it does the same transparent, warm thing; sometimes a Hansa yellow, PY65; sometimes with a touch of orange to deepen it. Recipes differ, so two brands' Indian yellows rarely match. The nickel azo versions are lightfast, which the original never was.

Here is where I land. The story is better than most pigment stories because it is half true, and the true half is the strange half. I own a modern Indian yellow and use it for one thing: the glow at the bottom of a sky. Nothing else does that, cow or no cow.

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 Indian yellow

You can get near the color with any warm yellow plus a touch of orange, thinned right down; what you cannot mix is the transparency. If the glow is what you want, buy a tube with PY150 on the label.

A cool red is the pairing that matters. Indian yellow with alizarin crimson or Poppy Bloom makes a sunset orange that still lets the paper through; with a blue it makes warm, transparent greens; over a dry wash of yellow ochre it turns a dull wall into a lit one. Keep it thin. Its whole personality lives in the thin layers.

Using Indian yellow in watercolor

Use it for the light itself: the bottom of a sunset sky, the rim of a backlit leaf, the warm side of a white wall at six in the evening. It is a color for the last inch before the sun.

Glazing is what it was made for. Let the painting dry completely, float a thin wash of Indian yellow over the part you want to warm, and walk away. It covers nothing, and that is the point: the drawing underneath stays and the temperature changes.

Pair it with the cool colors. A graded wash from Indian yellow at the horizon up into a blue sky is the oldest trick in landscape painting and still the best. Next to a violet shadow it glows; next to cadmium yellow it looks like syrup.

One thing I learned the hard way: it stains, and it travels. A brush that has touched Indian yellow will warm the next three washes if you do not rinse it properly, and a heavy stroke cannot be lifted. Keep a separate water jar for the yellows.

Indian yellow vs gamboge (and cadmium yellow)

Gamboge is the other historic transparent yellow, and the two did the same job for the same painters. Gamboge is a tree resin from Cambodia, yellower and a shade greener; Indian yellow is warmer and more orange. Both faded, both are hues today, and a modern new gamboge and a modern Indian yellow may even share a pigment.

Cadmium yellow is the opposite animal: opaque, mineral, permanent, a body color that sits on top of the paper. Indian yellow sinks in and lets the white through. Cadmium for the lit object, Indian yellow for the light around it.

If cadmium yellow is a lemon on a table, gamboge is the lemon's shadow on a yellow cloth, and Indian yellow is the late sun coming through the window behind them.

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.