Augustus Pleasonton, a brigadier general of the Pennsylvania militia of the American Civil War, spent the later years of his life contemplating the colour of the sky. His reflections led him to deduce that blue rays of light from the sun are the most conducive to plant and animal health. Subsequently, Pleasonton decided to install blue glass panes in his greenhouse and found that his grape vines had begun to flourish. The outcomes from a further series of DIY experiments led him to believe that his theory was correct. This new method, the ‘Cerulean Process’, gained traction and soon people were buying blue glass panes for their homes so they could experience the apparent health benefits of blue light.

Pleasonton ponders in his writings: whilst we know that white light refracts into colours, ‘profound ignorance prevails everywhere in connection with the influences that these elementary rays (of colour) develop.’[1] Pleasonton may have been wrong about the blue glass, but this statement provides some insight into our ongoing ignorance of the illusory qualities of light. Pleasonton’s own theory first came from a quasi-mystical experience of the blue colour of the sky. His imagination was captured by the effects of light, and this experience became his basis for a quasi-scientific study.

Samuel Murnane’s lithographic process revolves around the influence that light has at a chemical level. His approach to printing is as methodical and highly controlled as a laboratory experiment. A light-sensitive printing plate is exposed to light, operating in a similar way to film. Murnane breaks down an original photographic image into CMYK colour layers, and prints each layer individually to re-form the image. Our natural assumption is that we see the image in its’ completeness like a photograph. However, it is only the combination of these coloured layers that our eye detects, which forms an image.

Murnane both creates and conceptually interrogates illusion. He chooses the classic sign of illusion, the theatrical curtain; a threshold that is both penetrable and impenetrable. Physically we can move through the curtain, but in theatre, for instance, it clearly demarcates the fourth wall. The curtain absorbs light, blocking from our vision what lives on the other side. When the curtain is closed we are left with an undulating, impenetrable wall. The layers of illusion in Murnane’s work expand as we begin to realise these are curtains from arts institutions; Arts Centre Melbourne and the Kanazawa 21st Century Museum of Contemporary Art in Japan.

Windows and glass walls of these art spaces add to the number of thresholds depicted in Cerulean Process. These images hint that transparency does not preclude all things from being concealed. They make us acutely aware of the border of a space that can be seen but not accessed. Untitled (Arts Centre) looks into a more intimate, inner part of the Arts Centre that is not immediately accessible to the public. Empty and without patrons, it houses another reflection back to the street outside, both inviting in and repelling onlookers.

Alongside these images of recognisable settings also sit some more obscure prints where light has taken over and blurs out any indication of architectural spaces and borders. Light no longer plays the role of revealing, instead it conceals. When light is allowed to spill out and our eyes are no longer able to perform their usual trick of assembling an image, we are again met by a wall. This is a wall which withholds itself from interpretation. Alongside the more recognisable physical and temporal borders, these images simultaneously question and create the transcendence of illusion.

We can often tend to associate science with concrete facts, but looking at Pleasonton’s blue light theory we are reminded that science is still based on a set of fundamental assumptions. Illusion, the domain of art, also requires a set of fundamental assumptions, a suspension of disbelief, in order to operate. It plays with our preconceived notion that what we see is in fact present or true. In Cerulean Process iconic images of theatrical curtains alongside glass walls and windows are thresholds that suggest, but ultimately withhold, what is beyond them. Looking into the images we are left to contemplate the very frames and unacknowledged assumptions which exist around art institutions, vision, light and illusion.

[1]Augustus Pleasonton The Influence of the Blue Ray of the Sunlight and of the Blue Color of the Sky, 1877, Philadelphia

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