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  1. #81

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    Seems a little out of place but have mono bath
    print developers been discussed? Dan

  2. #82
    Ian Grant's Avatar
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    I think you'll find I mentioned them far back in the thread

    My company devised a formula (back in the late 70's) that worked extremely well with Ilford RC papers, and it was suggested that we market it, but I couldn't actually see a need for it other than for specialist uses, so our we just sat on it. I'll try and find it next time I'm in the UK and post it here on APUG.

    Ian

  3. #83
    Ian Grant's Avatar
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    Colour Monobaths

    Strange as it might sound I've just come across a Colour Monobath, actually it's designed for use as the 2nd developer in a specialist Reversal Process.

    "Colour reversal Developer/Fixer "Monobath"

    sodium sulphite 4 g
    sodium thiosulphate pentahydrate 54 g
    ammonium thiosulphate 6.6 g
    CD4 colour developing agent 15 g
    glycine 100 g
    sodium hydroxide 44.4 g
    sodium carbonate 40 g
    water to 1 litre
    pH 10.7 at 25°C


    The first developer was Kodak C41

    Ian

  4. #84
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    Ian;

    If the first developer formed a negative color image, then this one will form a positive color image and you will get black film. Now, if the glycine in that formula were glycin, then you might get no color at all due to competition, just a positive silver image. It depends on the activity of the CD-4 with the rest of the stuff there.

    The thiosulfate content is also much too low to do anything to a color film, but then again there would not be much free silver halide left by the time this thing starts to work.

    So, I ask, for what purpose was this odd duck devised?

    PE

  5. #85
    Ian Grant's Avatar
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    Ask Kodak

    I think the colour dyes are supposed to go walk-about into a receiver paper. I did think it odd that the first developer was C41, I would have thought a B&W first developer would be more appropriate.

    This developer and the final product cost Kodak far more money than they ever expected !!!

    Ian

  6. #86
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    Ian;

    Can you give a reference then?

    All of the color dyes that migrated used a plain activator of nothing but alkali and antifoggant. That was the Ektaflex activator. That is the only case I can remember.

    PE

  7. #87
    Ian Grant's Avatar
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    Ron, it was in a Kodak Harrow patent, EP0572620

    I assume rightly or wrongly this was part of the research programme into Kodaks Instant "Polaroid" type material. I came across it while looking for something entirely different.

    Ian

  8. #88
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    Thanks Ian, I read it over and find that the purpose of this quite escapes me. The best example had a B&W developing agent in the reciever sheet.

    At the time that was being done, I visited Harrow, and Mike and his wife were my hosts for part of the visit. I wish I had discussed this work with him, but we mostly 'caught' up since his prior visit to the US. All I remember is having a lovely roast beef with yorkshire pudding, visiting some old pubs for bangers and mash with mushy peas and gravy and going to the palace for a tour, but the guards were out and no-one was allowed in. I have a mediocre picture of the Concord and a duck flying in formation over the palace, and a few shots of Victoria station to show for it.

    And no information on Mike's process.

    PE

  9. #89
    Ian Grant's Avatar
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    Yes this is a perplexing patent, but I've read a quite few in the last few days and most are no better. Thinking back when I took out a Patent in the 70's what the patent agents wrote seemed quite meaningless and vague, so much that the Patent Office had to ask what's new before they'd grant the patent.

    Back to the Colour Monobath, the emulsion Mike's describing is C41 compatible, so in theory it could be used to develop any C41 emulsion, and possibly adapted for RA-4. But of course the silver image is still there and would need to be bleached out. So why use it - perhaps it takes away variables in the processing steps, a Monobath isn't particularly critical of temperature or time.

    Ian

  10. #90
    David A. Goldfarb's Avatar
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    Here's another test with Arista.EDU 400 (Fortepan, same as J&C Classic, Classicpan) rated at EI 200 but probably slightly underexposed since I'd metered the light closer to the window and was at max exposure for this camera without doing a time exposure. FX6a in the straight formulation with 90g hypo/l, 5x7" Press Graflex, Xenar 210/3.5 at f:3.5, 1/10 sec. Detail is from 1000 dpi neg scan.

    I've got a couple hundred sheets of this film in 4x5" and 5x7", so it seemed worth testing even though it is discontinued. I got a little dichroic fog, but it's not excessive. This is a neg scan, but I'd guess this neg would print well around grade 3. Results are quite grainy, but this is a format that I only contact print, so the grain isn't a big problem.
    Attached Thumbnails Attached Thumbnails Melchi,20March2008.jpg   Melchi,20March2008,dtl.jpg  
    flickr--http://www.flickr.com/photos/davidagoldfarb/
    Photography (not as up to date as the flickr site)--http://www.davidagoldfarb.com/photo
    Academic (Slavic and Comparative Literature)--http://www.davidagoldfarb.com

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