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  1. #1

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    Phenidone-C Developer pH?

    Disclaimer: I am no chemist, not even remotely close. This is just me monkeying around in ignorant bliss. Please correct me where my thoughts and assumptions are incorrect.

    Assumption #1: Phenidone-C developers need a pH upwards of 8 for active development. I've concocted and tweaked a few developers based on this assumption and it has worked out well (could just be dumb luck!).

    Here's where it gets interesting. I thought of trying a phenidone-c divided developer with phenidone+ascorbate in part A and alkali in part B. My proposed two-part developer is as follows:

    Part A:
    Ascorbic Acid - 80g
    Sodium Bicarbonate - 60g
    Water - 750mL (make sure all is dissolved and effervescence stops)
    Phenidone - 1g
    Water to make 1L

    Part B:
    Sodium Hydroxide - 1.45g
    Borax - 6.92g
    Water to make 1L

    Develop for 5 mins in each solution.

    The idea here being to make a highly concentrated part A to get a bunch of developing agents in the film and part B will increase the pH to make the developing agents active. As a point of reference a developer with 1g/L ascorbic acid + 0.025g/L phenidone + alkali (e.g. borax, carbonate) is very active.

    I tested this on small scale (100mL) with film clips just as an indication of activity. I expected to see no activity when in part A and see the film blacken when in part B. However, after about 2 mins in part A, the film was nearly black. At first I thought I contaminated part A causing the pH to go up but I checked with a calibrated meter and it showed 7.2 ... pretty much what I expected.

    So with my divided developer idea aside, does it make any sense that I saw active development in part A at such a low pH? This obviously disproves my earlier assumption but does anyone know what the active range for a phenidone-ascorbate developer is?

  2. #2

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    1st check my research PC-2bath here: http://www.apug.org/forums/forum37/9...tml?highlight=. I think that amount of phenidon/ascorbic acid is very high
    2nd someone on photo.net claim that if film placed in Diafine bath A for long time (45min?) and fix without processing in bath B you get printable negatives. Diafine is true 2bath developer with low pH of bath A

  3. #3

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    Yes, the amount of phenidone and vit-c is high. I tried one similar to what's posted in the thread but without sulfite and found it to be not active enough so I went for a "thick" part A hoping that more developing agent would get in the film and also having ascorbate preserve similar to what sulfite would do. What really got me was how fast part A was considering the low pH.



 

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