Together with fellow German artist Otto Piene, Mack co-founded the ZERO group in 1957, which sought a renewal in art amidst the ruins of post-war Germany. Created in the formative years of ZERO, Mack’s metal reliefs were made in his first studio in Düsseldorf at 69 Gladbacher Straße, which served as both an experimental laboratory for art and was the site of ZERO’s first exhibitions – “Abendausstellungen,” or “Evening Exhibitions” – that lasted the duration of one night.

Mack’s metal reliefs are characterized by their shimmering industrial surfaces, made from aluminum, Plexiglas, wood, glass and stainless steel: all materials that were radically unfamiliar for sculpture at the time. His aim was to abandon the traditional idea of pictorial space and focus instead on an overall surface play of light, reflection and vibration, in the process creating immaterial effects from material form.