This series was the initial event for the formation of the group ZERO (with Mack, Piene and Günther Uecker as its nucleus) and the international ZERO movement.

[1] In the early 1960s, Mack worked, with Gotthard Graubner, as an art teacher at the Lessing Gymnasium, Düsseldorf.

[2][3] In 1964 Mack, Piene and Uecker arranged the "ZERO Lichtraum (Hommage á Lucio Fontana)" at the 1964 documenta in Kassel.

From 1964 to 1966 Mack lived and worked in New York where the Howard Wise Gallery presented a solo exhibition in 1966.

In the same year he represented Germany at the 1970 Venice Biennale (together with Günther Uecker, Georg Karl Pfahler and Thomas Lenk).