Trial and error

I’ve finally reached the stage in my dry glass plate journey of pouring light sensitive emulsion onto my prepared plates.

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I’ve finally reached the stage in my dry glass plate journey of pouring light sensitive emulsion onto my prepared plates.

Apart from cutting, cleaning and subbing the glass over the past few weeks, I’ve been gathering together the bits and pieces I would need to have around me in the darkroom: Emulsion, wetting agent, trays and containers for water-bathing to maintain temperature of the emulsion, a container to pour the emulsion from, storage of the coated plates while the emulsion sets and a means of storing the finished plates until they are to be loaded into a camera.

  • Emulsion: The emulsion I’ve chosen to use is Silverprint’s SE1. It is supplied in solid form and has to be liquified by heating before use. I found that the water from my hot water tap, about 45ºC, was sufficient to liquify the SE1. It took about fifteen minutes with the bottle water-bathed in a large ceramic mug and the hot water changed every few minutes to maintain temperature.
  • Wetting Agent: I used Kodak Photo-Flo as a wetting agent to dilute the emulsion and to aid flow of the emulsion over the plates. I initially mixed my SE1 with approximately 25% Photo-Flo but this was too runny. Using SE1 without Photo-Flo was near impossible. I eventually settled on about 15%, or roughly 5ml Photo-Flo to 35ml SE1. This allowed the emulsion to be poured at a steady pace and to flow easily to the corners of the plate without too much spillage. (Yes, spillage was expected and spillage is what I got!)
  • Pouring Utensil: When I was shown how to pour emulsion a few months ago in the workshop at Street Level Photoworks, we used ceramic invalid feeding cups. I tried to short-cut the need for such ‘specialist’ equipment: I used a 50ml shot glass. My logic was that glass is inert so would not contaminate the emulsion, shot glasses have a heavy base and so would sit well in a water bath and as they are designed for the pouring of liquid they would be ideal for my purpose. I was wrong! The emulsion did not pour easily and as it spilled onto the edges of the glass the glass became slippery and difficult to hold. I did eventually master a ‘get-by’ technique but not before I’d wasted about 60ml of my 240ml bottle of SE1 to more spillage! A ceramic invalid cup (which of course has a handle and a spout) is now on its way from eBay!
  • Dark Storage: I’m pleased with my solution to laying out the coated plates and keeping them in the dark until they are dry: A table-top sized metal filing unit with five shallow drawers which I lined with cardboard on which to lay out the plates. I’ve draped the dark cloth made for my view camera over the drawer fronts to provide a light-seal that allows the unit to be moved to a more convenient location while the plates dry (when not in use for photographic purposes my darkroom serves as an en-suite shower room!).
  • Packaging: I will have four sizes of plates to store while they await use in a camera. The larger plates (5″x4″ and 5″x3″) will be stored in used photo-paper boxes but for the smaller plates I have made boxes to measure along the lines of simple pinhole cameras that I make regularly. Each plate will be separated from the next by a piece of baking paper and each package of plates will be enclosed in an opaque plastic bag before storage in its box. For each size plate I will also have a second box that will enable storage of exposed plates when reloading plate holders or cameras in the field.

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For this session I only coated the plates to use in my Countess 1/16 plate Camera and the 5″x3″ plates that I will use in my 2014 Worldwide Pinhole Photography Day pincam. I’ve used about half of my SE1 emulsion so far, about half of which was lost to spillage.

The small plates presented the most difficulty. Their weight and size made them difficult to support and maneouvre by supporting them by fingers on their underside. Inevitably I found myself holding them by the edges and this both disrupted the flow of emulsion across the upper surface and led to contamination of the underside as the emulsion ran down my (gloved) fingers. In this regard, the larger, heavier plates were much easier to work with. It was also difficult to see the emulsion pouring from the shot glass, due to the size of the glass and the fingers holding it obscuring what was happening. This should be resolved in future by the use of an invalid feeding cup which has both a handle and a spout! In future I will also ensure an ample supply of paper towels for keeping gloved fingers clean and dry as well as for mopping up the inevitable drips and spillages.

With lessons learned and what will hopefully be a better pouring utensil on the way I expect to have sufficient emulsion left to coat my remaining prepared plates. The 5″x4″ plates will be used in my Intrepid field camera the arrival of which is imminent, and the little 75mm x 25mm microscope slides will be used either in a custom built pincam or loaded in a 35mm camera.

Author: Donald Tainsh

A lifelong explorer of photography

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