Bridget Riley is considered one of the foremost proponents of Op-Art. One thing that bothered her during her college years was that she couldn't handle colour as she could handle line. In 1961 Riley painted her first black & white painting as a statement of intent. In 1966 she mixed a range of colours and in 1967 she began to use graded colours of turquoise and red increasing from grey to full strength, and subsequently full colour alone in a series of striped paintings. After a visit to Egypt she produced a series inspired by the unblended earth colours of the tomb paintings. In her later work there is a warmer element and the control of fugitive colour is more apparent.