"Riley's 'Op' paintings of the early 1960s were exclusively in black and white although, as her critical mentor the psychologist Anton Ehrenzweig noted, they could generate disembodied sensations of color. She was to begin incorporating color...
"In de Kooning's black canvases the elimination of color was conditioned as much by financial constraints as by the need to simplify pictorial problems in the spirit of Analytic Cubism. The deliberately artless use of shiny enamel housepaints...