April 2008

Monthly Archive

Silver Bleach/Etch

Posted by 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.

mordanc-1.jpg
The first try: maybe not very good print for the bleach/etch process, obviously the contrast is too low for the process. Only the darkest tones could be removed by rubbing in the first and second rinse. The print was fixed normally.

mordanc-2.jpg
After the process this print looked the same as the previous one, so it went through the process second time: more of the dark tones were lifted off.

Chemicals used:

    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:

    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.

mordanc-4.jpg
We need a contrasty image to use bleach/etch method succesfully. The process here was pretty normal, without rubbing the print too hard. The darkest tones were inverted due to emulsion lift. This one was fixed and washed normally.

mordanc-5-sml.jpg
Jalo Porkkala: Moscow 1979, mordancage print.

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.

mordanc-6.jpg
Same as the previous one, except the freely floating emulsion was rubbed off altogether. No fixing.

mordanc-7.jpg
Although it’s possible to achieve some stunning effects with emulsion lift and crinkle, it is more to my taste to use these in more subtle ways. I can keep most of the original image unchanged, and mordancage will only effect in the darkest shadow tones.

mordanc-8-sml.jpg
Jalo Porkkala: In Times Past, mordancage print.

This one is on a Bergger paper, which seems to let maximum blacks float easily. The print is unfixed and gently washed.

mordanc-9.jpg
Printed the same way, but this one was rubbed vigorously by hand during the washes. It looks more like a negative. Normal fixer and wash.

mordanc-10.jpg
Another sample of the flowing emulsion of Bergger paper. The print was not fixed, only washed shortly after the developer.

UV Blocking Again

Posted by on 02 Apr 2008 | Tagged as: Lumen / POP

To make another quick “Lumen” test for UV-blocking properties of an inkjet transparency, printed with an Epson 3800, we exposed a sheet of over-age Emaks paper through the printed film (as in the previous test on 28 Feb) in our UV-box for several hours during two days. The result is below (the color shift is quite interesting):

emaks-3800.jpg

There really is only one possible patch producing the lightest tone on this paper, corresponding to this particular “neon green” on the transparency: 0, 255, 170.

– – –

How will laser printers perform at the UV-blocking test then. Not very well, we can tell you:

emaks-laser.jpg

None of the color densities that the printer (Canon iRC3200) could output on it’s general use OHP transparency can’t hold UV-light, it will penetrate through all the hues almost equally well.

Now we are just waiting for the sunny spring days to come soon (with light rich in UV), so we can load our printing frames and leave them outside to expose some Lumen for us … 😉