When I want to do a painting with one colour overlapping another, it has to be a real overlap, not a depicted overlap. I didn't want to paint an overlap, meaning that it would be a deception or illusion. I no longer wanted to depict space, but to make a work that existed in literal space. Thus, my recent works are one canvas as a relief over another canvas. Another important example of a panel painting that explores the idea of the mural was Red Yellow Blue White 1952. It's the only one I ever did using actual dyed fabric of ready-made colours, which moves the painting into the realm of real objects.

In: 'Colour Chart I', interview with Christoph Grunenberg, 1 May 2009; 'Sixty years at full intensity', Tate 2009