The most commonly known facts about the artist Vincent van Gogh are that he cut off his left ear (actually only a part) and presented it to a prostitute, that he sold only one painting during his lifetime (actually there is evidence to suggest that it was more than one), and that he committed suicide (true).
Few realize quite how significant his contribution was to painting, that his adventurous use of color changed the direction of art. Van Gogh deliberately set about using colors to capture mood and emotion, rather than using colors realistically. At the time, this was completely unheard of.
"Instead of trying to exactly what I see before me, I make more arbitrary use of color to express myself more forcefully."
When he first devoted himself to painting full time, in 1880, Van Gogh used dark and gloomy earth colors such as raw umber, raw sienna, and olive green. These were very suited the miners, weavers, and peasant farm laborers who were his subjects. But the development of new, more lightfast pigments and his exposure to the work of the Impressionists, who were striving to capture the effects of light in the work, saw him introduce bright hues into his palette: reds, yellows, oranges, greens, and blues.
Typical colors in Van Gogh's palette included yellow ocher, chrome yellow and cadmium yellow, chrome orange, vermilion, Prussian blue, ultramarine, lead white and zinc white, emerald green, red lake, red ocher, raw sienna, and black. (Both chrome yellow and cadmium yellow are toxic, so some modern artists tend to use versions that have hue at the end of the name, which indicates that it's made from alternative pigments.)
Van Gogh painted very rapidly, with a sense of urgency, using the paint straight from the tube in thick, graphic brush strokes (impasto). In his last 70 days, he is said to have averaged one a day.
Influenced by prints from Japan, he painted dark outlines around objects, filling these in with areas of thick color. He knew that using complementary colors make each seem brighter, using yellows and oranges with blues and reds with greens. His choice of colors varied with his moods and occasionally he deliberately restricted his palette, such as with the sunflowers which are almost entirely yellows.
"To exaggerate the fairness of hair, I come even to orange tones, chromes and pale yellow ... I make a plain background of the richest, intensest blue that I can contrive, and by this simple combination of the bright head against the rich blue background, I get a mysterious effect, like a star in the depths of an azure sky."