The Palette/red/Dug out of the ground

Red ochre

The oldest colour humans used, the oldest evidence of symbolic thought, and still the cheapest pigment you can buy.

Also called haematite · sinopia · Indian red · ruddle · geru

Hex: #913831
RGB: 145, 56, 49
Pigment index: PR102
First used: At least 100,000 years, and used continuously since
From: Everywhere. There is red earth on every continent.

What it is

Iron oxide, mostly haematite (Fe₂O₃), mixed with clay and silica. Heat yellow ochre and you get this, the same iron with the water driven off.

How it is made

Dig it, dry it, grind it, wash it to sort the fine particles from the grit. That is all. No firing, no chemistry, no trade route. A child can make usable paint from a riverbank in an afternoon, which is exactly why it is the oldest one.

Heating is the one refinement that matters. Yellow ochre is hydrated iron oxide; put it in a fire and the water leaves, the crystal changes, and it turns red. This was understood extremely early. There is evidence of deliberate heat treatment of ochre going back tens of thousands of years, which means people were doing controlled chemistry to adjust a colour long before anything that would be called a civilisation.

Red ochre, Earth pigment of characteristic colour. Wikipedia's description, not ours.

The history

The Blombos Cave site in South Africa produced an ochre-processing workshop about 100,000 years old, abalone shells used as containers, with ochre ground and mixed with bone marrow and charcoal. There are engraved ochre blocks from the same site around 75,000 years old. This is among the earliest evidence anybody has for symbolic behaviour, and it is a colour.

It is in every cave painting: Chauvet, Lascaux, Altamira, Sulawesi, the Kimberley. It is in burials, bodies covered in red ochre have been found across tens of thousands of years and dozens of unconnected cultures, which is either a remarkable convergence or a very deep continuity. Nobody knows what it meant and everybody has a theory.

It never went away, and that is the part people miss. Red ochre is not a historical pigment. It is in the paint on a Swedish barn, the tilak on a forehead, the ground of a Pompeian wall, the red of a Greek vase, the primer under a car's paint, and the 'Indian red' in a school paintbox. The most used colour in human history is also the least glamorous.

Where it is used

Cave painting, body paint, burial, building paint, ceramics, and the whole warm-earth register of every oil painting ever made: flesh, shadow, brick, soil. Falun red, the Swedish barn colour, is iron oxide from a copper mine and is why rural Sweden is the colour it is.

For a brand palette, earth red is the colour that reads as 'made by hand' and 'from somewhere' more reliably than anything else, because everyone has seen it on a wall or a pot. It is also almost impossible to make look cheap, which no bright red can claim. If you want warmth without novelty, this is the family.

Go and look at it

The Blombos Cave ochre workshop
Iziko South African Museum, Cape Town
Abalone shells with ground ochre still in them, about 100,000 years old. The oldest known paint kit.
Chauvet and Lascaux
Ardèche and Dordogne, France: in situ, replicas open to visitors
Red ochre, yellow ochre and charcoal. Three pigments, and nothing painted since has surpassed the drawing.
Falun red barns
Across rural Sweden
Iron oxide waste from the Falun copper mine, made into a paint. An industrial by-product that became a national colour.

How it behaves

Made of: Iron oxide, mostly haematite (Fe₂O₃), mixed with clay and silica. Heat yellow ochre and you get this, the same iron with the water driven off.
Opacity: Opaque. It covers what is under it.
Lightfastness: Permanent. It will outlive the thing it is painted on.

Absolutely permanent and chemically inert. Nothing attacks iron oxide.
Cheap, strong, and slightly greyed, it cannot be pushed to a bright scarlet.
Dries fast in oil and makes an excellent ground.

The numbers

All derived from the hex, never typed beside it

HEX: #913831; What a browser and a design file want.
RGB: 145, 56, 49; The same three numbers in base ten. Light, not ink.
HSL: 4°, 49%, 38%; Hue, saturation, lightness, how a person describes a colour.
CMYK: 0, 61, 66, 43; Arithmetic only. A real separation depends on the press, the paper and a profile.
LAB: 36, 37, 24; Perceptual. L* of 36 is how light this actually looks, which HSL gets wrong.

This hex is an approximation, and a page about pigment has to say so. Red ochre 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 4°

Its opposite, by the diagram

#913831

#318A91

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

#913831

#A25650

#B2746F

#C89C98

#DEC3C1

#EFE1E0

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

#913831

#7B302A

#662722

#491C19

#2C110F

#160807

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
7.46:1 · AAA

Handgloves

Black on it
2.81:1 · Fails

Handgloves

It on paper
7.08:1 · AAA

Handgloves

It on ink
2.45:1 · 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.