The Palette/yellow/Made in a lab or a works
Cadmium yellow
The first brilliant yellow that does not fade, does not blacken and does not go brown, it only poisons the water supply.
- Hex
- #FFF600
- RGB
- 255, 246, 0
- Pigment index
- PY35
- First used
- Discovered 1817, commercial from the 1840s
- From
- Germany
What it is
Cadmium sulfide, CdS, with zinc or selenium to shift the hue.
How it is made
Cadmium sulfide is precipitated and then calcined at high temperature to grow the crystals. The particle size and the additives set the shade: pale lemon through to a deep orange-yellow. Friedrich Stromeyer identified cadmium in 1817 and noted its yellow sulfide; production waited decades for enough cadmium, which is a by-product of zinc smelting.
The calcination is the whole difference between a good cadmium and a poor one. Under-fired pigment is duller and less stable, and the cheap versions on the market are usually cadmium diluted with barium, 'cadmium yellow light' is sometimes half filler.
Cadmium yellow, Class of pigments that have cadmium as one of the chemical components. Wikipedia's description, not ours.
The history
Before cadmium, every bright yellow had a fatal flaw: orpiment poisoned its neighbours on the palette, Naples yellow was lead, chrome yellow went brown, gamboge and saffron faded, Indian yellow was unobtainable. Cadmium yellow was the first that simply worked, and it made the high-key palette of Impressionism and everything after it possible. Monet's late work, Matisse, the Fauves. All of it needs a yellow that will still be yellow.
Its history since is a long argument about whether a beautiful material is worth an environmental cost. Cadmium is toxic, accumulates in the body and in soil, and industrial uses have been restricted worldwide. The EU has twice moved to restrict artists' cadmium colours and twice been argued down, most seriously in 2014 when a Swedish proposal was rejected after opposition from painters, manufacturers and conservators.
That argument is a good model for how to think about material restrictions generally. Both sides were right about something: cadmium in the water supply is a real harm, and the quantity contributed by artists' paint is small enough that restricting it is close to symbolic. The difficulty is that the symbolic restriction is also the easiest one to pass.
Where it is used
Artists' paint, and formerly plastics, glass, glazes and enamels. Mid-century yellow plastics and enamelled steel are usually cadmium.
As a colour it is a bully. It is the most saturated opaque yellow available and it will dominate any composition it is in, which is why it works on a warning triangle and why it fails on a package that wants to look considered. If you want a yellow with warmth and no aggression, an ochre or a Naples-type pale will get you there, and you will spend less time compensating.
Go and look at it
Monet's late waterlilies
Musée de l'Orangerie, Paris; MoMA, New York
High-key yellow that has not moved in a century. The pigment is the reason the pictures still read as light.
How it behaves
- Made of
- Cadmium sulfide, CdS, with zinc or selenium to shift the hue.
- Opacity
- Opaque. It covers what is under it.
- Lightfastness
- Permanent. It will outlive the thing it is painted on.
Hazard
Cadmium sulfide. Toxic and a cumulative environmental pollutant. Never sand, spray or breathe.
- Completely lightfast and stable in every medium, which is why it survived.
- Often adulterated with barium in cheaper tubes; check for 'cadmium-barium'.
- Sulfide chemistry, so it can darken if it meets copper pigments.
The numbers
All derived from the hex, never typed beside it
- HEX
- #FFF600
- What a browser and a design file want.
- RGB
- 255, 246, 0
- The same three numbers in base ten. Light, not ink.
- HSL
- 58°, 100%, 50%
- Hue, saturation, lightness, how a person describes a colour.
- CMYK
- 0, 4, 100, 0
- Arithmetic only. A real separation depends on the press, the paper and a profile.
- LAB
- 95, -17, 93
- Perceptual. L* of 95 is how light this actually looks, which HSL gets wrong.
This hex is an approximation, and a page about pigment has to say so. Cadmium yellow 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 58°
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
1.14:1 · Fails
Handgloves
Black on it
18.43:1 · AAA
Handgloves
It on paper
1.08:1 · Fails
Handgloves
It on ink
16.05:1 · 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.
Read more, elsewhere
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Foundations · Colour·yellow·Made in a lab or a works