and varied shapes. Stripe 1961 However After Image became too limited for Kidner, he found that he wanted to approach colour in a more rational way, so he began a series of striped paintings using two alternating colours. Moire 1963 By 1963, Kidner had recognised the limitation of 2 colours, the problem of how to introduce a third colour was solved for him in an article on the Moire effect in the Scientific American. This effect was first discovered in Japanese silks, when the material was folded, optical patterns and colours floated above the actual patterns and colour of the material. This method produced a dramatic effect when Kidner crossed 2 colour bands with a third at a slight angle, resulting in a completely new pattern, with a wave like vertical image hovering into view producing an intense optical dazzle. Wave 1969 The appearance of the wave captivated Kidner and wave theory became his obsession as he realised that a wave pattern produces many more possibilities than straight lines because waves can be put in or out of phase. As well as optical effects he was interested in distinguishing form from colour. He applied 3 colours to 4 forms in rotation so that no form could be identified by a particular colour. This can be seen in his print Sussex 1967 Columns In 1969 the notion of colour as form urged Kidner on to do a columnar sculpture of a wave. At this stage he became interested in Number theory as the key to "the nature of order" and "the structure of reality". Kidner was influenced by Lohse, a pioneer of systems art who had written that "Through its relation to structure, technology, science etc (The ) task is to set up systems". Kidner meticulously translated the column into a two-dimensional form as a painting by using a systematic method of measurements and colour-coding as seen for example in: Grids and lattices 1973 and stretched elastic, 1987 At this stage Kidner began to be interested in the spaces between the lines and crisscross wavy lines began to emerge in his work, culminating in grids and lattices. These were sometimes in phase creating identical spaces in between and then sometimes out of phase so the spaces in between didn't repeat. Kidner used this structure as a basis for creating many variations of this principle and observed that " the endless number