Optical mixing
Put tiny dots of color side by side, step back, and your eye blends them into one.
- Method
- Pointillism, or divisionism
- Key text
- Ogden Rood, Modern Chromatics (1879)
Optical mixing happens when small patches of color sit so close that the eye can't separate them and blends them into one. Step back from dots of blue and yellow and they merge. Because the eye averages light, the blend comes out a soft warm grey, not the green you'd get by mixing the two paints. Your phone screen works this way: tiny red, green and blue lights fuse into every color. So does printing, with dots of cyan, magenta, yellow and black.
In the 1880s Georges Seurat and Paul Signac turned this into a method, often called pointillism or divisionism. They had read Chevreul on contrast and the American physicist Ogden Rood, whose Modern Chromatics (1879) discussed colors mixing in the eye. Seurat spent about two years on A Sunday on La Grande Jatte, placing small strokes of separate colors side by side.
The theory promised brighter color than mixing on the palette, since paint mixtures get duller, especially mixes of complements. In practice the eye averages the dots, so from a distance divisionist paintings tend to look soft and a little muted. What they gain is shimmer: up close the dots vibrate against each other; far away they settle.
Time has altered the dots too. Seurat used a new zinc yellow that has browned: strokes that were bright yellow now look like ochre, and greens have drifted toward olive. Researchers have built digital reconstructions of the brighter original. The looser broken color of the Impressionists works on the same principle.
Swatches
- Dots of blue...
- ...and yellow...
- ...average to a warm grey
Colors
Sources
- Rood, O. N. (1879). Modern Chromatics. New York: D. Appleton.
- Berns, R. S. (2006). Rejuvenating the color palette of Georges Seurat's A Sunday on La Grande Jatte—1884: a simulation. Color Research & Application 31(4).
- Art Institute of Chicago (2004). Seurat and the Making of La Grande Jatte.
Hex values are screen approximations. Every page lists its sources.