American artist Sam Francis (1923-1994) brought vivid colour and emotional intensity to Abstract Expressionism. He was described as the 'most sensuous and sensitive painter of his generation' by former Guggenheim Museum director James Johnson Sweeney, and curator Howard Fox called him 'one of the acknowledged masters of late-modern art.' Francis's works, whether intimate or monumental in scale, make indelible impressions; the intention of the artist was to make them felt as much as seen. At the age of twenty, Francis was hospitalised for spinal tuberculosis and spent three years virtually immobilised in a body cast. For physical therapy he was given a set of watercolours, and, as he described it, he painted his way back to life. The exuberant colour and expression in his paintings celebrated his survival; his five-decade career was an energetic visual and theoretical exploration that took him around the world. Francis' idiosyncratic painting practices have long been the subject of speculation and debate among conservators and art historians. Presented here for the first time in this volume are the results of an in-depth scientific study of more than forty paintings from the late 1940s to early 1990s, which reveal new discoveries about his creative process, inventive techniques, and specially formulated paints and binders. The data provides a key to the complicated evolution of the artist's work and informs original art historical interpretations.