The Palette/red/Made in a lab or a works
Alizarin crimson
The first natural dye ever synthesised, which is why madder farming died, and it still is not lightfast enough, which nobody likes admitting.
- Hex
- #E32636
- RGB
- 227, 38, 54
- Pigment index
- PR83
- First used
- 1868
- From
- Germany, and London, within a day of each other
What it is
1,2-dihydroxyanthraquinone, laked onto alumina. The same molecule as the main colourant in madder root.
How it is made
Graebe and Liebermann worked out alizarin's structure and made it from anthracene, a coal-tar product, in 1868. The commercially viable route came the following year, and BASF's patent application and Perkin's were filed a day apart, the closest patent race in the history of dyes.
The pigment is made by laking the synthetic dye, the same precipitation onto aluminium hydroxide that madder lake uses. What you get is more consistent and much stronger than the plant version, because there is one molecule in it instead of a dozen.
Alizarin crimson, Chemical compound and histologic stain. Wikipedia's description, not ours.
The history
This is the moment the chemical industry proved it could replace agriculture. Before 1868 a synthetic dye was a new colour that nature did not have, mauveine, fuchsine. After 1868 a synthetic dye could be an existing natural product, made better and cheaper in a factory. The madder fields of Avignon and Zeeland were gone within about fifteen years, and the indigo plantations followed thirty years later on the same logic.
Painters adopted it immediately as a cheap, strong, permanent-seeming crimson, and it has been on every palette since. The 'permanent-seeming' is the problem: alizarin crimson is rated moderately lightfast at best, and in thin washes or tinted with white it fades noticeably within decades. A lot of twentieth-century painting has quietly lost its reds.
Most modern tubes labelled 'alizarin crimson' or 'permanent alizarin' are quinacridone-based substitutes (PR177, PV19) that match the colour and actually last. Reading the pigment index on a tube rather than the name on the front is the single most useful habit in materials, and the same principle applies to every specification you will ever write: the marketing name is not the material.
Where it is used
Painting, printing ink, and textiles historically. Its useful property is that it is a cool transparent red. It glazes, and it makes convincing dark purples and near-blacks with green and blue that no opaque red can.
In a palette, alizarin is what you reach for when a red needs to sit back rather than come forward. Cadmium red advances at you; this recedes. Put them side by side at the same value and the difference is entirely in the transparency, which is a variable most colour pickers do not have.
Go and look at it
Faded reds in late 19th and 20th century painting
Any modern collection
The pinks that have gone grey. Conservation reports name this pigment often.
How it behaves
- Made of
- 1,2-dihydroxyanthraquinone, laked onto alumina. The same molecule as the main colourant in madder root.
- Opacity
- Transparent. It stains rather than covers, so it can be glazed over another colour.
- Lightfastness
- Moderate. It will move, noticeably, within decades, faster in thin films and tints.
- Genuinely not lightfast in tints and thin films, despite its reputation.
- Most tubes sold under the name today are quinacridones. Check the index number.
- Slow drying in oil and prone to cracking if used thickly.
The numbers
All derived from the hex, never typed beside it
- HEX
- #E32636
- What a browser and a design file want.
- RGB
- 227, 38, 54
- The same three numbers in base ten. Light, not ink.
- HSL
- 355°, 77%, 52%
- Hue, saturation, lightness, how a person describes a colour.
- CMYK
- 0, 83, 76, 11
- Arithmetic only. A real separation depends on the press, the paper and a profile.
- LAB
- 49, 69, 40
- Perceptual. L* of 49 is how light this actually looks, which HSL gets wrong.
This hex is an approximation, and a page about pigment has to say so. Alizarin crimson 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 355°
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
4.57:1 · AA
Handgloves
Black on it
4.60:1 · AA
Handgloves
It on paper
4.34:1 · Large text only
Handgloves
It on ink
4.00:1 · Large text only
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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