It was brought to the fore in the late 1950's and early 60's, when artists like Judd, Flavin, John Chamberlain, Claes Oldenburg, Yves Klein and Lucio Fontana began to take strong undiluted color beyond the traditional materials of painting and sculpture.

The painting in "To the Bridge" is a 13 1/2-foot spread of fan shapes filled with strokes of virtually undiluted color, except for the corners, where the canvas is bare, save for lacey, frondy shapes in pencil.

He had a bout of gestural painting in the 1950's, but his preferred method, at both the start and finish of his career, was a somewhat cerebral, fastidiously executed geometric style, its potential for dryness mitigated by subtly varied textures, undiluted color and flashes of pictorial wit.

Look back and you can see van Gogh's undiluted color, Malevich's geometry, Picasso's Cubism and Leger's Purism, all pulverized and reconstituted in an American vernacular.

Mix a little extra medium into undiluted colour and you will find that you have a stronger, deeper colour, which holds up well (brushes out slower).

LaGundia is credited with inventing leaky-edge abstraction whereby undiluted, raw color shoots from within the edges of the rectangle rather than going beyond it.

The artist's sculptures often have the bright undiluted colors, simple forms and implied geometric systems of Minimal art.

Also good to see are the slightly later (mid-1980's) videos by the Canadian collective General Idea, made with a savage appreciation of television culture and the art world's foibles, as well as a bracing sense of undiluted color.

His 1911-12 "Chiropodist (in the Bathouse)" is a monstrous yet endearing reprise of Cezanne's "Cardplayers," while the undiluted colors of these works also reflect his exposure to Matisse.

Ben Shahn's tempera study "Carpenters" of 1942, with its flatness and broad areas of undiluted color, gives some sense of the originality that Shahn also brought to mural art.