Pop artists such as Tom Wesselmann, Jim Dine, and James Rosenquist also took up the shaped canvas medium. Robin Landa writes that "Wesselmann uses the shape of the container which Landa means the canvas to express the organic quality of smoke" in his "smoker" paintings. According to Colpitt, however, the use of the shaped canvas by 1960s pop artists was considered at the time to be something other than shaped canvas painting properly speaking: "At the same time, not all reliefs qualified as shaped canvases, which, as an ideological pursuit in the sixties, tended to exclude Pop art." (op. cit., p. 52)