He became abstract in 1947; between 1948 and 1949 he creates Work of Arts with letters: "I GRIDI." In 1950, he establishes in Milan and engages himself in an expression where stains are largely used. His works are presented in October 1951 in Florence. This is the first exhibition of informal art in Italy. Its works are known under the name of NUCLEAR Art. At the end of that year, he arrives in Paris, where in May 1952, he has his first personal exhibition (Arnaud Gallery). After a study trip in Spain, back in Paris, he enters the René Drouin Gallery. In 1954, he takes part in the May Fair. In 1957, he is part of a group "espaces imaginaries" proposed by Restany. He travels a lot throughout Europe, presenting his exhibitions in Bruxelles, Copenhague, Schiedam, Amsterdam. He leaves for the United States, where he works with the Gres Gallery in Chicago. In 1961, he is invited at the Konsthall of Lund (Sweden) for an important retrospective, which is renewed at the Palais of Beaux-Arts of Bruxelles. He comes nearer of "NOUVEAU REALISME" and in 1962 exhibits at the J. Gallery "Pays Reel". He leaves for Morocco where he stays for a long time. He starts photography report on canvas and in 1965 he signs the first manifest "MEC-ART". He will afterwards continue his work in this direction. He goes back to Milan and during the 70's, he creates two visual poetry reviews: in 1971 "Mec" and in 1972 "Lotta Poetica". He then lives in Bratislava (Slovaquia) and goes back to Paris. In 1984, an important retrospective is dedicated to him at the National Center of Plastic Arts. He is nominated as "Chevalier de l'Ordre des Arts et des Lettres". In 1988 and 1989, he creates a series of works on the Gulf War called "Pour ne pas oublier" and in 1992, a new series on "Antonin Artaud".
In 2000 Centro d'arte Spaziotempo tribute him an anthological exibition "Percorsi" and in 2002 in Palazzo Lanfranchi di Pisa. In 2006 two exhibitions: the first at GAM Gallarate dedicated to the early years of his carreer (from 1949 to 1953) and then at Colossi arte contemporanea. Bertini has attended the most significant exhibitions all around the world, although he concentrated on Europe and the U.S.A. For many years, Bertini has had a presence at the Biennale of Venice, Salon de Mai, and Salon d'Octobre in Paris. His works are included in many private and public collections as well as in many museums. During the 1960's, Bertini was a promoter of Mec-Art, along with Yehuda Neiman, Alain Jaquet, Mimmo Rotella and Nikos.