"Painting has always fascinated me when it is filled with light. But painting is a lot more than that to me; it is the foreground to the infinitely deep, black space in which light and colour have become an indivisible one. The identity of light and colour, which are visible in the spectrum, is the subject of my paintings - it is their only subject."

Colour intensity is always an intensity of light. "Because for me colour is always colour as light and light as colour which I try to capture and to bring into form in my paintings the term colour intensity is always a qualitative term for light intensity - that said under the understanding that the term intensity is an aesthetic term, not a physical one." The quietness, subtleness, softness, sphericalness, transparency and immateriality of the colour can just as well determine the intensity as an expressively and roughly applied colour.

It is the style of Mack's chromatic pictures that the colours segue into one another unnoticeably and in the tiniest of nuances without losing a further important character namely that of going from step to step and showing succinct colour contrasts in these steps. Even then each concentration of a colour carries a lightening and vice versa. This smooth transition from one colour to the next contrasting colour is only possible because Heinz Mack adds so to say a smaller colour step in between the contrasting pairs which mediates between the bigger steps. In the case of colour chromatics many intervals, steps, sequences, colour rhythms, rapports and oscillations are created. In the ZERO era, Heinz Mack called this the vibration of colour; nowadays he talks more of oscillations as a way of describing the dynamic principle occurring between the individual colours.

Forms only have the role of a rhythmic restriction in Mack's chromatic paintings, a restriction within which light as colour can appear. If a light chromatic painting consists of many pure light colours and their individual concentrations and lightenings then, depending on the number of such, it can be either a darkly saturated or a bright picture full of light. That the colour temperatures at the same time determine the sensuality of the colours, and that this is greater the softer and more picturesque the colour is applied, or in diaphanous layers allows the light of the colours to oscillate - all these are conditions for a rich, complex radiation of colour in which dynamic and rhythmic oscillations find exciting yet harmonic relationships with one another.