Until the late nineteenth century, no school or movement in art had been founded on science. It’s true that developments in realist painting during the Renaissance took advantage of Brunelleschi’s perspective projection, but it was contributory rather than its basis. Then in 1884, the young French painter Georges Seurat (1859–1891) launched a completely new style and movement developed from scientific research by Hermann von Helmholtz, James Clerk Maxwell, and Thomas Young: Neo-Impressionism, Divisionism or Pointillism.

The nineteenth century had seen the rise of colour theory, and the first experiments on colour vision. Seurat was moved by the writing of scientists like Helmholtz who proposed that colour could be used in painting according to natural laws. He attempted to create a new language of painting derived from natural sciences, although not being a scientist by training he relied mainly on the writing of Ogden Rood, who in turn interpreted the science of Helmholtz.

Beneath this was the longest-standing dispute in painting, whether form (disegno) or colour (colorito) should be dominant, which has always struck me as a profoundly flawed question. With the French Impressionists in the avant garde at the time, the emphasis was already on colour, which had also been enabled by the supply of high chroma pigments, many of them synthetic.

The French chemist Michel Eugène Chevreul, who worked for the world-famous Gobelins tapestry factory, had noticed the perceived effects of one colour on an adjacent colour, developed and formalised the ideas of colour contrast and complementary colours, and preached colour harmony. Ogden Rood was an American physicist who worked extensively on colour, and published the influential book Colour, A Text-Book of Modern Chromatics in 1879, which appeared in French translation two years later. Among its fundamental lessons is the distinction between additive and subtractive colour, and differences in the results of mixing primary colours.

Seurat’s first and greatest masterpiece, generally known as La Grande Jatte, uses the technique of optical mixing of colour. Rather than blending pigments on the canvas, it’s constructed of tiny dots which are high in chroma, and allow for optical mixing, one of the fundamental techniques in Seurat’s new scientific painting. His theory was that the mixing of colour would then occur in the retina of the viewer, and he tried this in a pure landscape study (above), and in his huge finished painting (below).

This was painted in three phases. In the first, the dots he applied were mixed from available and fairly conventional pigments, including duller earths. In the second phase, he used a limited number of brighter and higher chroma pigments. In the third and final phase he added coloured borders which are distinctive of his paintings.

With that complete, and exhibited at the eighth and last Impressionist Exhibition and the Salon of the Société des Artistes Indépendents in 1886, he turned to another monumental work which is less well-known, Les Poseuses (Posers, or Models).

Various preparatory drawings exist in different collections, but the three main figure studies made by Seurat for this painting are in the Musée d’Orsay, and confirm that the three figures in the finished works were painted from the same model, were produced separately then composited into the whole painting, and during that process two of the three were partially dressed, one with a white fabric wrap, the other with green stockings.

Each was painted using Seurat’s Divisionist technique on the wooden lid of a cigar box, which the artist termed a croqueton, his favourite support for such sketches. Between 1886-88, he painted two different versions of Les Poseuses: the full-sized version currently in The Barnes Foundation, Philadelphia, and a smaller version which he painted in the same year, which used to be on display in the National Gallery, London, but has now returned to Berlin.

The smaller version retains his Divisionist technique, and is visibly grainy.

The larger appears far ‘smoother’ in the texture of its colour.

A detail view of the latter painting demonstrates that Seurat still constructed it from dots of paint, but like his studies it doesn’t rely as much on the optical mixing of colour from high-chroma pigments.

In 1890, Seurat started work on another large Divisionist painting, in which he returned more to the optical mixing of La Grande Jatte. He was still finishing it in March 1891 when it was exhibited at the Salon des Indépendents. Its deep internal contradiction is the artist’s choice of a painstakingly slow and mechanical method of painting, for a motif which is full of spontaneous movement and action.

A few days later, Georges Seurat was dead.

Tomorrow I’ll look at where Divisionism went in the hands of his colleagues and successors.