Henri's disciples were known collectively as the Ashcan School, partly because of the lowlife subjects they painted, but also because of the gritty, expressive handling of paint, which you can see in the swift brush strokes of "Forty-two Kids, " and Bellows's famous painting of an illicit prizefight, "Stag at Sharkey's" (1909).

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It took about a month to make all three paintings, a process that was slowed by Mr. Boyle's request that Mr. Cobb shoot stop-motion photographs every few brush strokes, for a sequence toward the end of the film in which the painting gets "unpainted" so that the audience can appreciate all the layers involved in creating the work.

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Given a choice between an exhibit of German Expressionist paintings and a hike up some soul-stirring hill, I'll take the thick brush strokes and green faces every time.

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