Divisionism is a style of painting that involves using pure color, applied in dabs or bars of color, coined by Paul Signac, a Post-Impressionist and student of Georges-Pierre Seurat in his book published in 1899 called D’Eugène Delacroix au Néo-Impressionnisme. While Divisionism is similar to Pointillism, it differs from the technique in subtle ways.
Imagine the world of the late 1800’s – the Impressionists have successfully revolted against the French painting establishment and have exhibited their work as a mockery to academic perfection. Now enters Georges-Pierre Seurat, a young painter that studies the works of color theorists like Charles Blanc, Michel Eugène Chevreul, and Eugène Delacroix and begins to play with the color in a whole new way, developing first, Pointillism, and then teaching the concept to Paul Signac, who develops it into Divisionism.
The first Pointillist work is a famous piece of art called Sunday Afternoon on the Island of La Grande Jatte, (left) painted from 1884 and completed in 1886, created by Georges Seurat. Divisionism began emerging in later works from Paul Signac called The Port of Saint-Tropez painted in 1901 (right).
As you can see, Signac used larger dabs of paint, instead of the smaller dots to create is colors. The idea of Divisionism is for the pure colors to show, not hiding them, yet allowing the eye to optically blend the colors from a distance. In a Pointillist work, the painter would use red and yellow next to each other, but as you can see, in The Port of Saint-Tropez, Signac clearly uses pre-mixed orange in the church and distant buildings, along with their reflections on the water.
Vincent van Gogh was influenced by Paul Signac, after meeting him in 1887 in Asnières. He began incorporating Pontilisit principles of contrasting colors, using blues against orange to create vibrant works. Later that year, he created Bridges across the Seine at Asnieres, clearly a Divisionist work, using the long streaks of paint throughout the compositon, as seen below. He later went on to incorporate these Divisonist principles into other works, such as Self-Portrait 1887 (row 2, right), and Starry Night 1889, (row 2, left).

In Self-Portrait, you can clearly see the use of green next to the reds in his beard, in his eyes and eyebrows.
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