The color wheel for oil painters: hue, value and chroma

A phone screen mixes light: red, green and blue add to white. Paint subtracts: each pigment absorbs part of the light falling on it, and a mixture absorbs everything either parent absorbs. That is why blue and yellow light make grey but blue and yellow paint make green, and why mixing more colors together always moves towards dark mud. It is also why a hex code on a screen cannot be translated into a recipe by arithmetic — the PaintMixLab engine models how each pigment absorbs and scatters light across the spectrum, then searches for a mix that lands on the color you asked for.

For painters the practical wheel has twelve hues: three primaries (red, yellow, blue), three secondaries (orange, green, violet) and six tertiaries (red-orange, yellow-orange, yellow-green, blue-green, blue-violet, red-violet). Opposites on this wheel are complements and neutralise each other; neighbours are analogous and mix cleanly.

No tube is a perfect primary. Every red leans either towards orange (Cadmium Red Light, Vermilion) or towards violet (Alizarin Crimson, Quinacridone Magenta); every blue leans towards green (Phthalo, Cerulean) or towards violet (Ultramarine); every yellow leans towards green (Lemon, Hansa) or towards orange (Cadmium Yellow Deep). This lean is called color bias, and it decides whether a secondary comes out clean or dull. Mix a violet-leaning red with a green-leaning blue and the hidden green and orange cancel each other: you get a greyish purple. That is not a mistake; it is subtraction working as it should. See color bias and the split-primary palette for the six tubes that solve it.

1. To darken a color, add its complement or a darker neighbour, not black. Black kills chroma and often shifts hue.
2. To lighten, add white — and expect the color to cool and lose chroma. A little yellow with the white keeps warm colors warm.
3. To grey a color without changing its value much, add a small amount of its complement.
4. To shift hue, add the neighbour on the wheel in the direction you want to go.

These moves are the whole vocabulary of mixing. Here is what they look like as calculated recipes for real paint sets:

TealRecipe by paint setMauveRecipe by paint setOlive GreenRecipe by paint setTerracottaRecipe by paint setNavy BlueRecipe by paint set

Painters use “tone”, “tint” and “shade” loosely. Strictly, a tint is a color plus white, a shade is a color plus black, and a tone is a color plus grey. Value and chroma describe the same ideas more precisely, and they are the words used throughout these guides and in the app.