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Old 15th November 2020, 06:19 PM
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Roy_H Roy_H is offline
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Join Date: Nov 2008
Location: Suffolk
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Default UPDATE: Using Mike Ware's Process

...not for the faint-hearted!

Ammonium Iron(III) Oxalate arrived so decided to follow Mike Ware's instructions for his revised mix.
(https://www.mikeware.co.uk/mikeware/...e_Process.html)
This is a one-solution coating mix that has a shelf life of a year or more in a dark stoppered bottle kept in the dark.

Thanks to his clear instructions, all went well. As I've been unable to source any ammonium dichromate (once used for the - now banned - indoor firework 'Mount Vesuvius' & highly flammable) I substituted it with 0.5ml of 20% w/v potassium dichromate.

Advisory: It's not an easy mix as it needs to be carried out at 43℃ and I would have struggled without my heated magnetic stirrer, as the solutions are highly saturated. Gloves, mask, safety glasses or face screen, protective apron or HazMat suit recommended...
But I've survived, it worked and I coated some watercolour paper (Scribble & Dot) last night.

I made test strips (below) as this coating is supposedly more sensitive than the traditional one. In practice, I found it was much the same.

Exposure was 6 minutes to my UV lamp at around 40cm. The 8x10 negative was on Pictorico transparency film, an image translated from a digital original. I've shown the original and its negative counterpart, the latter adjusted somewhat to improve shadow densities.

Development was in a 1.5% citric acid bath for 2 minutes, rinsed in cold running water and then given 1 minute in a very dilute hydrogen peroxide solution. Rinsed again until no visible yellow stain remained (a minute or so).

Very pleased with the blue obtained and the tonal range seems very good. There appeared to be no loss in density during the washing cycles but only time will tell if any residual chemicals in the paper affect the image.

1: The finished print
2: The test strips
3: The digital negative
4: Conventional print
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Last edited by Roy_H; 15th November 2020 at 06:24 PM. Reason: minor typo
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