The answer lies in the exploration of pattern. The works can be read, first and most easily, as beautifully structured patterns that shift through different scales of order as the observer reads them through the different geometric layers invoked by, for instance, sequences of pentagrams or Mandelbrot forms. Elements of the work are rotated, reflected and translated. Symmetries are deployed in colour and line. Surfaces are layered and resonating patterns established. Shapes may be printed onto the surface ground; colour may be bled in from behind, its bleeding into gesso creating minute instances of Mandelbrot interactions. Works may be treated a dozen times in different ways. Chance is invoked at every turn, in a shifting of careful sequences of pattern responsive to the overall nature of the physical painting plane.

Colours are keyed to the quality of colours in light in the particular environment as it is lived in: in Sydney her images shimmered in the bright Australian heat; here they have become more sombre as she explores the deep blues and green-blacks of this environment, particularly its bush. She describes these darks as a renegotiation with McCahon, who taught her in the 1960s; and particularly with his concern for the optical experiences of this country (merging with shadows as a foil to dazzling and penetrating light sources).

Yet colour offers the dimension of undecidability. Colour is always undecidable in its operations. The tomato is, functionally red, but where does its redness reside? Issues of naming and definition provide philosophers and psychologists with apparently unresolvable problems because the act of isolating colour from object appears to be virtually impossible, yet is a tenet of everyday experience. Coats describes here the way colour and structure combine in her work.

Layers of colour are worked across each other to touch off 'disorder' and to generate structural separation within their associations. There are points of meeting which are variable within each layer. When it happens that two or more layers (each of which had been developed independently through assessment of the whole field) meet within the field, that indicates the beginning of an image formation. The whole field remains conjoined with these points of congregation and this geometry of symmetry, while relative to the frame, repeats within and beyond the frame creating a flexible stability. This occurrence of meeting is something I observe during the initial process and is an indication that I have found an image that may become a series of paintings.1

This object or image if virtual; it may not be grasped except in relationships, yet is undeniably active. What, then, contains it?

Coat's use of the net-like effects formed by interference patterns provides part of the answer. Thomas Young first investigated interference patterns in 1802. They are caused by two wave trains encountering each other; they produce intersections of calm and disturbance. John Tyndall wrote of them, 'Through their interference the water surface is sometimes shivered into the most beautiful mosaic, trembling rhythmically as if with a kind of visible music'.2 They were central to the question of whether light should be described in terms of waves or particles. Coats's 'Morphic' images invoke them explicitly. They occur through surface effects: reflective and ridged surfaces set up dynamic interactions and resonances with underlying colours. In the glass works they occur through layered rather than surface intersections. Such patterns set up complex colour effects that literally hold the viewer's gaze by asking for concentration. Patterns, harmonies, symmetries and the deep reading of space engage the viewer's whole sensorium, her affective as well as her intellectual capacities. When images, particularly pale ones, are combined in groups the viewer must orientate herself by resolving intersections and dissonances. Colour sequences and combinations jump and disintegrate systems. The 'object' that the viewer grasps is virtual. The process of reading it, Coats suggests, moves the viewer toward an equilibrium, a holding pattern.