The scientists of color

We owe a great debt to the engineers and scientists of the 19th century. In many ways, they invented modern painting.
In the Time of Harmony. The Golden Age is not in the Past, it is in the Future, 1893–95, Paul Signac, Mairie de Montreuil

A friend once told me engineers were ‘boring.’ Having now been married to one for 37 years, I can tell you that she was wrong. Equally importantly, we wouldn’t have much art without science and engineering. Art rests on discoveries in the physical world.

Bright Earth: Art and the Invention of Color by Philip Ball is a fun read. It also makes the serious point that art isn’t created merely by artists. Art incorporates the scientific and engineering innovations of its day.
Ball’s emphasis is on the advances made in pigment technology in the 19th century, and how they influenced Impressionism. That’s true as far as it goes, but scientific insight into perception also influenced how painters handled color.
Impression, soleil levant (Impression, Sunrise), 1872, Claude Monet, Musée Marmottan Monet. This painting is what gave the movement its name.
Michel Eugène Chevreul was a famous French chemist. He is best remembered for having invented margarine. He was also the director of the dye works at the Gobelins Manufactory in Paris. In trying to make a uniform black dye, he realized that a color was perceived differently based on its setting. This lead to the idea of simultaneous contrast, which in turn led to the Impressionist understanding of complementary colors.
Scientists have a great influence on art, but they are sometimes reactionary. Chevreul believed chiaroscuro was the most important element in creating natural, or lifelike, paintings. Instead, Impressionists turned to his color relationships to define light and shadows.
Scottish physicist James Clerk Maxwellis most famous for his theory of electromagnetic radiation, but his interests were wide. He was particularly interested in color perception, color-blindness, and color theory. Using linear algebra, he proved that all human color perception was based on three types of receptors. He is the father of colorimetry, or the systematic measurement of color perception.
An image of James Clerk Maxwell’s color photograph of a tartan ribbon. Scanned from The Illustrated History of Colour Photography, Jack H. Coote, 1993
Based on his research into the psychology of color perception, Maxwell designed the first color photography system. He proposed that a color photograph could be made by shooting three black-and-white pictures through red, green and blue filters and then projecting it in the same way. He demonstrated this first color photograph in 1861.
American physicist Ogden Rood was also an avid painter, a member of the American Watercolor Society. Rood divided color into three constants: purity, luminosity, and hue. In 1874 he gave two lectures to the National Academy of Design in New York on Modern Optics in Painting.
La Récolte des Foins, Éragny, 1887, Camille Pissarro, Van Gogh Museum.
Rood suggested that small dots or lines of different colors, when viewed from a distance, would blend into a new color. He believed that the complementary colors of his color wheel, when applied in pairs by the artist, would enhance the presence of a painting: “… paintings, made up almost entirely of tints that by themselves seem modest and far from brilliant, often strike us as being rich and gorgeous in colour, while, on the other hand, the most gaudy colours can easily be arranged so as to produce a depressing effect on the beholder.”
Rood’s theory of contrasting colors influenced Impressionism, and was particularly influential on  Georges-Pierre Seurat. Seurat called his new style chromo-luminarism; Pointillism was a derogatory term invented by his critics. We are now so used to optics experiments in painting that we hardly  give any thought to their origins. But we, along with the painters who came before us, owe a great debt to the work of Maxwell, Chevreul, Rood and others.