CONTEMPORARY MASTERS art stage. become a global practice. FOREWORD - tably four leaders of the abstract movement. Hans Hartung, Master of informal art and undoubtedly the other side, Sam Francis developed in his abstract works a new aesthetics of colour that is now widely recognised. - dary names like Andy Warhol and Tom Wesselmann. They depict the urban scene and give visibility to the immense world of consumer goods that are the daily surroundings of these societies.