Anthony Caro encountered modernism when working as an assistant to Henry Moore in the 1950s. After being introduced to the American sculptor David Smith in the early 1960s, he abandoned his earlier figurative work and started constructing sculptures by welding or bolting together pieces of steel such as I-beams, steel plates and meshes. "Twenty Four Hours" (1960), in Tate Britain since 1975, is one of his earliest abstract sculptures in painted steel. Often the finished piece was then painted in a bold flat colour.