The Palette/brown/Dug out of the ground
Sienna
An iron earth with manganese in it, and the single most useful brown in painting because it is transparent where other browns are mud.
Also called raw sienna · burnt sienna · terra di Siena
- Hex
- #8A3324
- RGB
- 138, 51, 36
- Pigment index
- PBr7
- First used
- Prehistoric; named from the Sienese deposits in the Renaissance
- From
- Tuscany originally; now largely Sardinia and elsewhere
What it is
Iron oxide with manganese oxide and clay. Burnt sienna is the same earth roasted, which takes it from a golden brown to a red-brown.
How it is made
Dug, washed, dried and ground, and then, for burnt sienna, roasted. Heating converts the hydrated iron oxide to haematite and the colour swings from a warm yellow-brown to a distinctly red one. Same earth, two tubes, and the only difference is a fire.
The Tuscan deposits near Siena gave the name and the reputation. They are largely worked out, so most sienna sold now comes from Sardinia or is a synthetic iron oxide adjusted to match, which is chemically fine and slightly duller.
Sienna, Earth pigment. Wikipedia's description, not ours.
The history
Sienna, umber and ochre are the three earth families and between them they do most of the work in most paintings. What distinguishes sienna is transparency: it is a brown you can glaze with, which means it can warm a passage without covering it. Umber is more opaque and heavier, and ochre is fully opaque.
Burnt sienna has one property that painters treat as close to magic: mixed with ultramarine it gives a range of greys, browns, and near-blacks that covers most of what a picture needs for shadow, and the two together are a complete palette for a monochrome study. It is one of the standard two-colour mixes and it has been for centuries.
The word entered English through Italian in the eighteenth century and then, in the twentieth, into a crayon box, which is where most people meet it. Burnt sienna is one of the few pigment names that a general audience still recognises.
Where it is used
Everything warm and everything in shadow: skin, wood, earth, rust, hair, stone. Also the standard underpainting and toning colour for a canvas.
For anyone building a palette, the earths are the colours that make the brights work. A bright red next to a bright blue fights; the same red against a burnt sienna sings. Almost every palette that feels cheap is missing its earths. It has four saturated colours and a grey, and nothing that reads as a physical surface.
Go and look at it
The toned ground of almost any oil painting
Look at an unfinished picture in any collection
The warm brown under everything. Usually this or an umber.
How it behaves
- Made of
- Iron oxide with manganese oxide and clay. Burnt sienna is the same earth roasted, which takes it from a golden brown to a red-brown.
- Opacity
- Transparent. It stains rather than covers, so it can be glazed over another colour.
- Lightfastness
- Permanent. It will outlive the thing it is painted on.
- Transparent, unlike most browns, which is what makes it useful for glazing.
- The manganese content speeds drying in oil considerably.
- With ultramarine it produces a full range of greys and blacks, the classic two-colour mix.
The numbers
All derived from the hex, never typed beside it
- HEX
- #8A3324
- What a browser and a design file want.
- RGB
- 138, 51, 36
- The same three numbers in base ten. Light, not ink.
- HSL
- 9°, 59%, 34%
- Hue, saturation, lightness, how a person describes a colour.
- CMYK
- 0, 63, 74, 46
- Arithmetic only. A real separation depends on the press, the paper and a profile.
- LAB
- 34, 36, 28
- Perceptual. L* of 34 is how light this actually looks, which HSL gets wrong.
This hex is an approximation, and a page about pigment has to say so. Sienna 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 9°
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
8.14:1 · AAA
Handgloves
Black on it
2.58:1 · Fails
Handgloves
It on paper
7.73:1 · AAA
Handgloves
It on ink
2.25:1 · Fails
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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