Richard Hamilton first made contact with Dieter Roth in 1961, having seen some of his books the previous year. From then until Roth's death in 1998, the two artists collaborated on numerous projects as well as developing a close friendship based on mutual admiration for each other's work. Their personalities and approaches to art were in many ways totally different, but this, no doubt, was part of the attraction. For Roth the collaborations were always...