Born in 1928 at New Castle, Indiana, as Robert Clark. Between 1945 and 1948 he studied at art schools in Indianapolis and Utica, and from 1949 to 1953 at the Chicago Art Institute School and the Skowhgan School of Painting and Sculpture, Maine.
In 1953 and 1954 he went to the Edinburgh College of Art and London University, after which he settled in New York. He took up contact with the painters Kelly, Smith and Youngerman. His early works were inspired by traffic signs, automatic amusement machines, commercial stencils and old tradenames. In the early sixties he did sculpture assemblages and developed his style of vivid color surfaces, involving letters, words and numbers.
In 1966 he had exhibitions in Düsseldorf, Eindhoven (Van Abbemuseum), Krefeld (Museum Haus Lange) and Stuttgart (Würtembergische Kunstverein).
He was represented at the Documenta “IV” exhibition, Kassel, in 1968. He became known for his silkscreen prints, posters and sculptures which took the word LOVE as a theme. The brash directness of these works stemmed from their symmetrical arrangements of color and form.