Heron painted this work over a period of eleven months, from August 1958 to July 1959. From 1957 he had begun to experiment with vertical and horizontal bands of colour in his paintings. With this particular work Heron now combined both elements on the same canvas. Built up over time, the different layers of colours intersected, overlapped and ate away at one another, creating the soft-edged square shapes now visible. As the artist himself explained: 'I did not draw these shapes in this configuration - the shapes and their relationship grew out of this process of allowing each colour area to adjust physically to adjacent colour areas'.