Blue and The Impressionist Painters
The invention of new synthetic pigments in the 18th and 19th centuries considerably brightened and expanded the palette of painters. J.M.W. Turner experimented with the new cobalt blue, and of the twenty colours most used by the Impressionists, twelve were new and synthetic colours, including cobalt blue, ultramarine and cerulean blue.
Another important influence on painting in the 19th century was the theory of complementary colours, developed by the French chemist Michel Eugene Chevreul in 1828 and published in 1839. He demonstrated that placing complementary colours, such as blue and yellow-orange or ultramarine and yellow, next to each other heightened the intensity of each colour "to the apogee of their tonality." In 1879 an American physicist, Ogden Rood, published a book charting the complementary colours of each colour in the spectrum. This principle of painting was used by Claude Monet in his Impression – Sunrise – Fog (1872), where he put a vivid blue next to a bright orange sun, (1872) and in Régate à Argenteuil (1872), where he painted an orange sun against blue water. The colours brighten each other. Renoir used the same contrast of cobalt blue water and an orange sun in Canotage sur la Seine (1879–1880). Both Monet and Renoir liked to use pure colours, without any blending.
Monet and the impressionists were among the first to observe that shadows were full of colour. In his La Gare Saint-Lazare, the grey smoke, vapour and dark shadows are actually composed of mixtures of bright pigment, including cobalt blue, cerulean blue, synthetic ultramarine, emerald green, Guillet green, chrome yellow, vermilion and ecarlate red. Blue was a favorite colour of the impressionist painters, who used it not just to depict nature but to create moods, feelings and atmospheres. Cobalt blue, a pigment of cobalt oxide-aluminium oxide, was a favourite of Auguste Renoir and Vincent van Gogh. It was similar to smalt, a pigment used for centuries to make blue glass, but it was much improved by the French chemist Louis Jacques Thénard, who introduced it in 1802. It was very stable but extremely expensive. Van Gogh wrote to his brother Theo, "‘Cobalt is a divine colour and there is nothing so beautiful for putting atmosphere around things…"
Van Gogh described to his brother Theo how he composed a sky: "The dark blue sky is spotted with clouds of an even darker blue than the fundamental blue of intense cobalt, and others of a lighter blue, like the bluish white of the Milky Way....the sea was very dark ultramarine, the shore a sort of violet and of light red as I see it, and on the dunes, a few bushes of prussian blue."
Claude Monet used several recently-invented colours in his Gare Saint-Lazare (1877). He used cobalt blue, invented in 1807, cerulean blue invented in 1860, and French ultramarine, first made in 1828.
In Régate à Argenteuil (1872), Monet used two complementary colours together — blue and orange — to brighten the effect of both colours.
Umbrellas, by Pierre Auguste-Renoir. (1881 and 1885). Renoir used cobalt blue for right side of the picture, but used the new synthetic ultramarine introduced in the 1870s, when he added two figures to left of the picture a few years later.
In Vincent Van Gogh's Irises, the blue irises are placed against their complementary colour, yellow-orange.
Van Gogh's Starry Night Over the Rhone (1888). Blue used to create a mood or atmosphere. A cobalt blue sky, and cobalt or ultramarine water.
Wheatfield under clouded sky (July 1890), One of the last paintings by Vincent van Gogh, He wrote of cobalt blue, "there is nothing so beautiful for putting atmosphere around things."