The Palette/yellow/Grown
Turmeric
The yellow in your kitchen, your wedding, your mustard and your pH indicator, and it will not survive a week on a windowsill.
Also called haldi · curcumin · Indian saffron · E100
- Hex
- #E1AD01
- RGB
- 225, 173, 1
- First used
- At least 4,000 years in South Asia
- From
- India, still around three-quarters of world production
What it is
Curcumin, a polyphenol, from the rhizome of Curcuma longa.
How it is made
The rhizome is boiled or steamed, dried and ground. That is it: no extraction, no lake, no mordant needed for a quick dye on cotton, which is why it is the most accessible dye on earth and why it is what everyone's first natural-dye experiment uses.
It needs no mordant and it fails for the same reason: nothing is holding it. Curcumin sits on the fibre and light takes it apart within days of real exposure.
Turmeric, Plant used as spice. Wikipedia's description, not ours.
The history
Turmeric's role in South Asia is not primarily as a colourant, it is as a substance: food, medicine, ritual. The haldi ceremony before a Hindu wedding, the marking of thresholds, the Ayurvedic use, the antiseptic use on wounds: the yellow is a side effect of a material that is doing several jobs at once.
As a dye it was used for cheap cloth, for monks' robes where gamboge was unavailable, and for paper. It was also, constantly, the substance used to fake saffron, which is the most persistent fraud in the history of the spice trade.
It has a second technical life as a chemical indicator. Curcumin turns from yellow to red in alkali, so turmeric paper is a real reagent for testing for bases and for boron. A kitchen spice is a laboratory indicator, which is the kind of fact that makes colour chemistry worth paying attention to.
Where it is used
Food colouring at industrial scale (E100, in mustard, butter, cheese, sweets) plus textile dyeing, ritual use, and cosmetics. Not used as a serious artist's pigment, because it will not last.
The pH trick is a genuinely good thing to have done once. Paint turmeric water on paper, dry it, then write on it with a cotton bud dipped in baking-soda solution: the writing comes up red. Twenty minutes, and you will never again think of a colour as a fixed property of a substance.
Go and look at it
A haldi ceremony
Across South Asia
The colour applied to skin before a wedding. Ritual first, dye second.
The ingredients panel of a jar of mustard
A kitchen
E100. The yellow of the world's cheapest condiment.
How it behaves
- Made of
- Curcumin, a polyphenol, from the rhizome of Curcuma longa.
- Opacity
- Transparent. It stains rather than covers, so it can be glazed over another colour.
- Lightfastness
- Fugitive. It leaves. Work made with it is already less than it was.
- Fades in days of direct sunlight. It is the least permanent colourant in common use.
- Turns red in alkali, which makes it a working pH indicator.
- Stains everything permanently except, ironically, the thing you wanted dyed.
The numbers
All derived from the hex, never typed beside it
- HEX
- #E1AD01
- What a browser and a design file want.
- RGB
- 225, 173, 1
- The same three numbers in base ten. Light, not ink.
- HSL
- 46°, 99%, 44%
- Hue, saturation, lightness, how a person describes a colour.
- CMYK
- 0, 23, 100, 12
- Arithmetic only. A real separation depends on the press, the paper and a profile.
- LAB
- 73, 7, 76
- Perceptual. L* of 73 is how light this actually looks, which HSL gets wrong.
This hex is an approximation, and a page about pigment has to say so. Turmeric is a substance. A ground mineral scatters light from thousands of separate grains at slightly different angles, and no single sRGB value is that event. It is a flat average of a photograph of it, and the real thing is outside what a screen can emit. Use the number to specify a screen colour. Do not use it to judge the pigment.
Where it sits on the wheel
Hue 46°
Its opposite, by the diagram
The arithmetic opposite, 180° round in HSL. Useful, and not the same as the opposite a painter mixing pigment would name, that wheel was built for paint.
Lighter and darker
Towards white
Mixing with white does not only lighten, it dulls and cools. This is why a pale tint of a brand colour so often looks chalky, and why a designed light shade beats a generated one.
Towards black
Mixing with black kills the hue as it darkens. A better dark is usually the colour plus its neighbour round the wheel, which is what every painter does instead.
Can you set type on it
Handgloves
White on it
2.06:1 · Fails
Handgloves
Black on it
10.18:1 · AAA
Handgloves
It on paper
1.96:1 · Fails
Handgloves
It on ink
8.86:1 · AAA
4.5:1 is the floor for body text and 3:1 for large text, by WCAG. Treat it as a minimum you may not go under rather than as a target: plenty of pairs pass at 4.6:1 and are still unpleasant to read for a page, and the checker will not tell you that.