Complementary colours

Why the pairs differ

The two lists disagree because they answer different questions. With light, two colours are complementary if together they add up to white. Red light lacks exactly what cyan light supplies. With paint, each pigment soaks up part of the light, and two complements between them soak up nearly all of it, leaving a dark neutral. The traditional painter's pairs are also only roughly right. If you mix real paints, the colour that greys a red most cleanly is usually a blue-green, closer to the pair that light gives than to the green of the school wheel.

What they do side by side

Put a small patch of orange on a blue ground and both look more intense than they would alone. The French chemist Michel Eugène Chevreul described this in 1839 after years of fielding complaints about dull colours at the Gobelins tapestry works in Paris. The yarn was fine. The fault lay in what it was woven next to. Painters took up his findings: the orange boats on blue water in Impressionist pictures are a direct use of them. Where two strong complements of equal lightness meet, the edge can seem to shimmer, which is tiring in text.

Using them

A painter rarely darkens a colour with black. A touch of the complement lowers its strength while keeping it lively, so a red is quietened with a little green. Shadows are often painted with a hint of the complement of the light. In design, a complementary pair is the simplest way to make one thing stand out, which is why so many film posters set orange against teal. It works best when the two are unequal: plenty of one, kept quiet, and a small amount of the other at full strength.

Colours on this page

Also part of it, and being written: Orange.

Sources and further reading

• Complementary colors on Wikipedia
• National Gallery, London: Complementary colours
• Webexhibits, Color Vision and Art: Simultaneous contrast