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 exhibiting locally in Hampstead while attending Quintin Grammar School before studying at Chelsea Art School from 1963 to 1967, graduating with BA (Fine Art) Upper 2nd Hons. Since then he regularly exhibited paintings and photographs, represented in private collections in Great Britain, Japan and the USA, as well as practising as a graphic designer. 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, 1996 and in Brighton, 1997.
His works on paper were shown for the first time at Gonville and Caius College, Cambridge in 1970 followed by one-man exhibitions at:
1973, Rotunda Gallery, Hampstead, London
1988, Casson Gallery, Eastbourne
1991, Poetry Centre Gallery, London
Selected mixed exhibitions include:
1963, 1965, 1967 John Moores Liverpool Exhibition
1966 Young Contemporaries, Tate Gallery
1980 FPS Trends, Mall Galleries, London
1987 Athena Art Awards, Barbican Centre
1996 Sites, Tricycle Gallery, London
1996-7 Les Sixties: France et Grande Bretagne 1960-1973, Paris & Brighton