Weissmann's interest in art was awakened at the age of about fourteen by reproductions of pictures by modern painters such as Picasso, Klee, Kandinsky and Jackson Pollock and developed by contact with established living artists. He was well known for a series of LSD paintings in the mid-sixties done whilst under influence of this drug. His most famous painting drain' 1966 is one of the best examples of this psychedelic period, featured in the touring exhibition Les Sixties: France et Grande Bretagne 1960-1973 in Paris.