Captured on glass

It’s almost 100 years since New South Wales police used glass-plate negatives to photograph suspects in custody. These negatives are a direct link to that moment in time, and provide evidence about photographic technology and methods in the 1920s.

After setting up his camera in the holding yard at Central Police Station, the police photographer determined an exposure for the light falling on the subject in front of his lens, directed the sitter into the frame and clicked the shutter to expose the plate. The action of light on the emulsion created a latent image that, after chemical processing, became the negative. This was printed and the resulting portraits were used by police to identify suspects and investigate crimes.

Today these negatives form part of the New South Wales Police Forensic Photography Archive. Spanning 1910–64, the archive comprises different types, formats and sizes of negatives. For me, each one raises questions: how and when was this negative exposed, what camera did the photographer use, and what was their intention? My research into the mugshots known as the Specials has led to insights into the photomechanical processes as well as the technical and practical challenges the photographers might have faced.

The evidence of the negative

A negative tells us more about a photographer’s practice, technology and methods of production than any finished print could. It’s the in-camera view – a direct physical link to the moment in time when the photograph was taken, and to the photographer and the scene they preserve.

The Specials photographs are dry glass-plate negatives – fragile sheets of glass coated in gelatin silver emulsion. The image is tonally inverted on the plate, so that the bright areas appear dark and the deep shadows have no presence. Handwritten inscriptions are visible on one side of the plate. Often the smooth image surface is interrupted with marks, abrasions, dust and policemen’s fingerprints. The passing of time is evident where the emulsion shimmers silver, is yellowing at the edges or has been washed away. A close examination of these objects allows us to see what the photographer produced and understand how the technology shaped the police photographer’s work and the qualities of their images.

Channelling the police photographer

Recently I had an opportunity to hand-make dry glass-plate negatives in a workshop at Gold Street Studios in Trentham, Victoria. The large-format negatives, analogue view camera (with manual exposure settings), slow emulsion, unpredictable lighting conditions, chemical processes and moving subjects all reflected the experience of the police photographer at work in the 1920s. We started with a piece of glass, which we prepared, coated, exposed and processed, then contact printed to produce a photograph. The experience demonstrated both the camera craft required to obtain a well-focused, correctly exposed negative and the technical knowledge needed for darkroom processing and mixing chemicals.

In the 1920s, the police photographer would have had to gain the suspect’s participation, working quickly to execute his photographic portraits. This era of photographic technology necessitated exposure times of anywhere from less than a second to a few seconds, as shown where sitters have moved during the exposure time, causing a blur in the final image. Given the apparent challenges in capturing these images, including the unpredictability of the subjects, the technical and aesthetic quality of these New South Wales Police images are all the more remarkable.