[1][5] In childhood he showed a talent in drawing and briefly studied under Venetian painter Luigi Scarpa Croce (1901–1967).
[5] In 1926, when he was 18 years old, he showed his work for the first time at Ca 'Pesaro in an exhibitions highlighting young artists at the Bevilacqua la Masa Foundation.
[5] From this experience he made friends with art critic Giuseppe Marchiori [it], and painter Leone Minassian.
[5][9] In 1946, Santomaso and Emìlio Vedova were introduced by art critic Marchiori to Peggy Guggenheim in Venice.
[7][10] In the same year 1946, he signed an antifascist manifesto alongside Giuseppe Marchiori, Renato Birolli, Bruno Cassinari, Renato Guttuso, Ènnio Morlotti, Armando Pizzinato, Emìlio Vedova, Leoncillo Leonardi, and Lorènzo Viani; this group later formed the Fronte Nuovo delle Arti art movement.