In 1958 Piero Manzoni exposed with Lucio Fontana, the founder of the Spatialism, and with Enrico Baj, the founder of the Nuclear Art: "Fontana, Baj, Manzoni" (in Bergamo in January and in Bologna in April) and "L'avanguardia" (Galleria Montenapoleone, Milan, opened May 27; works by Enrico Baj, Lucio Fontana, Piero Manzoni, Francis Picabia, Antonio Sant'Elia).
22 April-4 May: Manzoni's personal show at the Galleria Pater, in Milan.
Piero Manzoni co-edited with Baj and Sergio DAngelo the third number of the Nuclear Movement's review "Il Gesto" (the first issue of which appeared in June 1955). One of his Achromes was reproduced. This is Manzoni's last official cooperation with the Nuclear Movement.
The departure from the Nuclear Movement was marked by the encounter with Agostino Bonalumi and Enrico Castellani. The three artists took part in a mixed exposition at the Galleria Pater (with Biasi, a member of the Nuclear Movement, the English Situationist Ralph Rumney and Douglas Swan). In December Manzoni, Bonalumi, Castellani appeared again in a collective show at the Galleria Prisma (Milan, 1-10 December), still linked to a group of artists connected with the Nuclear Movement.
Manzoni, Bonalumi, Castellani exposed as a threesome at the Galleria Prisma (Milan, 16-18 February), and in April they shared a show together at the Galleria Appia Antica in Rome.
In 1959 Manzoni began his series of Achromes composed of squares of canvas cut up and stitched together. At a solo show in the Bar La Parete in Milan, the new canvases were termed "Superfici acrome" (colourless surfaces). This is the first true appearance of the name "Achrome".
In summer Manzoni took part in Zero Group shows at Rotterdam (Rotterdamsche Kunstkring, "Zero", 1-28 July) and Wiesbaden (Galerie Boukes, "Dynamo", 10 July-7 August).
Manzoni's Lines were shown for the first time at the Pozzetto exhibition in Albisola (18-24 August). One of the black cylindrical containers was opened as a demonstration model. The Line (19.43 metres in length) was unrolled around the gallery, and was immediately damaged by an indignant spectator.
In the autumn of 1959 Manzoni began his contributions to the Roman periodical "Il Pensiero Nazionale" and published with Castellani the first issue of "Azimuth". The avant-garde review was followed in December by the opening of Azimut, a gallery run by Castellani and Manzoni (Milan, via Clerici 12). The first issue of "Azimuth" review appeared at time of the gallery inaugural exhibition: "Manzoni" (4-24 December).