When the ceramic sculptures were first displayed to the public, the Düsseldorf archi-tect Helmut Hentrich reported, "Now Mack has opened up again a brand new me-dium for himself, following his famous colleagues Eduardo Chillida, Lucio Fontana, Joan Mirò and Antonio Tàpies. In ceramics he has discovered the oldest handcraft material in the world which mankind made useful in his earliest cultures."
Simple Euclidian forms and volumes characterize the designer shapes of the sculp-tural works from Heinz Mack. It is exactly these forms which also characterize his works from the fire. In the beginning Mack had the declared intention of working with the material clay purely as a sculptural material. He told his co-workers in the Kölner Keramikstatt where the works were created and fired right from the beginning that he had no intention of using the traditional technique of modelling clay by hand; finger-prints as an expression of spontaneous shaping were not his thing. The artist himself was surprised when he himself broke the ban which he had imposed. Almost unbe-known to him the material clay and its characteristics forced itself to be designed and modelled on the surface with the hands.
Also in respect of colours Mack remained true to himself. He had always refused to "paint" his sculptures because he gave preference to the individuality provided by the materials. This is what he also did in his ceramic works. The endless range of colours in his ceramic works is taken exclusively from the glaze. In doing so he used the cen-turies old tradition of glazing fired objects to his own purpose and developed it even further in an artistic way.
Nonetheless Heinz Mack does not see himself in the light of the traditional "Arts du Feu". His colours are more derived from the axiomatic basic theme of his artistic creativity, which draws its richness of colour from the chromatics of the spectrum of light.

The artist's own comment on this: "From the end of the ZERO era until now I have preferred pure colours, colours which are present in the spectrum of light, as a se-quence, as a harmonious order, structured, as a coherent continuity of light.  Under continuity I understand that each colour of light follows upon the one which has gone immediately before it, to change itself chromatically into the next colour of light."