Scientific Backgrounds and Influences - Eugene Chevreul

Chevreul was perhaps the most important influence on artists during the 19th century; his great contribution was producing the color wheel of primary and intermediary hues.

Chevreul was a French chemist who restored old tapestries. During his restorations of tapestries he noticed that the only way to restore a section properly was to take into account the influence of the colors around the missing wool; he could not produce the right hue unless he recognized the surrounding dyes. Chevreul discovered that two colors juxtaposed, slightly overlapping or very close together, would have the effect of another color when seen from a distance. The discovery of this phenomenon became the basis for the Pointillist technique of the Neoimpressionist painters.
Primary: Yellow, Blue, Red
Secondary: Orange, Green, Violet
Intermediary: Red-Orange, Yellow-Orange, etc.
Chevreul also realized that the 'halo' that one sees after looking at a color is actually the opposing, or complementary, color. For example: After looking at a red object, one may see a green echo/halo of the original object. This complementary color (as an example, green for red) is due to retinal persistence. Neoimpressionist painters interested in the interplay of colors made extensive use of complementary colors in their paintings. In his works Chevreul advised artists that they should not just paint the color of the object being depicted, but rather they should add colors and make appropriate adjustments to achieve a harmony. It seems that the harmony Chevreul wrote about is what Seurat came to call 'emotion'.