Mordancage
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Silver Bleach/Etch
Posted by Jalo on 10 Apr 2008 | Tagged as: Mordancage
Mordançage is a special post-printing process where the silver emulsion of a black&white photograph is bleached and “softened” in a solution containing copper chloride and hydrogen peroxide. The process is quite old, it was developed in 1890s. In the literature of that time it was referred to as “bleach/etch” or “gelatin relief” and such. The name “mordançage” comes from Jean-Pierre Sudre, a French photographer, known for his experiments with photographic chemistry, among other things. There is a good overview of the process by Christina Anderson on the Unblinking Eye website.
The Mordancage solution is used to bleach and partly dissolve the photographic emulsion, so that parts of it can be totally rubbed away, and the darkest parts may lift off from the paper base. After bleaching the image is redeveloped in a paper developer or toner. The image will reappear as positive or negative, or both, depending on the degree of bleaching, washing and rubbing the print, and also on the strength of the peroxide in the solution.
The mordancage process can be done in normal room lighting. The images to be mordancaged can be freshly printed and still wet, or you can use dry prints made beforehand. In this experiment we were using prints that were made on Bergger and Forte fiber base papers a couple of weeks before.
Chemicals used:
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Solution A
Water, 750 ml
Copper chloride, 30 g
Kodak Max-Stop, 100 ml
Water, to make 1000 ml
Solution B
Hydrogen peroxide 30 %
was diluted 1 + 1 with water to make approx. 15 %.
Working solution
A and B mixed together in equal parts just before use.
Mix and use the working solution only in well ventilated room!
The process:
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1. Bleach: the wet print is immersed in the mordancage solution for 3 – 6 minutes, or until fully bleached.
2. Rinse in water for a few minutes. At this time the emulsion can be rubbed lightly with fingertips (wearing gloves), soft brush or sponge.
3. Redevelop: Dektol 1 + 4, 2 – 4 minutes, as need be.
4. Rinse in water again (more of the emulsion may lift off).
5. Standard fixer (we used Agfa Agefix), if possible without totally removing the emulsion. For more effect the process may be done again from step 1.
6. Final wash for 5 – 10 minutes (carefully!), if possible without totally removing emulsion.
Here the darkest tones started floating in the developer – I wanted to keep them in the picture, so I didn’t fix at all, and washed very carefully only for a few minutes.
This one is on a Bergger paper, which seems to let maximum blacks float easily. The print is unfixed and gently washed.
