ilford rapid fixer

Discussion in 'Darkroom Developing and Printing' started by Beppe Alborè, Jun 16, 2004.

  1. Beppe Alborè

    Dan Quinn Guest

    RE: (Dan Quinn) wrote
    I've made an error. I'll correct and restate today. Dan
     
    Dan Quinn, Jun 21, 2004
    #21
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  2. Don't forget the difference in capacity. Ammonium thiosulfate fixes
    about 3 or 4 times as much film as the sodium salt.
     
    Michael Scarpitti, Jun 21, 2004
    #22
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  3. Beppe Alborè

    Dan Quinn Guest

    Busy day. Based on Photo. Formulary's price of $16.95 a gallon for
    A. Thio and $29.50 for 5lbs of anhydrous S. Thio. the price ratio is
    $1 dollor to $2.37. That is the cost ratio for thiosulfate ion, S2O3.
    The weight ratio is 1.56 to 1; the A. Thio being the heavier per
    unit S2O3.
    So the price per unit is less but the shipping per unit is more.
    I have not included the NH4 in the calculation because it is
    uncertain just how much of which halides of silver it will
    complex. I believe it will increase capacity with the
    chloride and less so with the bromide. Dan
     
    Dan Quinn, Jun 22, 2004
    #23
  4. Beppe Alborè

    Dan Quinn Guest

    IIRC, I bought that bottle in 2000.
    I'd suppose Ilford's Film strength paper archival processing
    recommendations still apply.
    An Acid Rapid fixer for a monobath? Perhaps the neutral S. Thio.
    would be better.
    What might have inspired that?
    There's the rub. How about 20 minutes to fix? A large tank would
    be required and a very dilute fix. Dan
     
    Dan Quinn, Jun 22, 2004
    #24
  5. I presume so -- I haven't spent that much effort on it, and don't yet
    have my wet darkroom set up.
    No doubt it would be, or TF4. I was working with what I had or could
    easily and quickly get, a quick hack after reading that no one had
    produced a monobath based on a rapid fixer because of the very short
    required dev time.
    It was a handy, easy to measure alkali that I knew would be compatible
    with both ammonium thiosulfate and the ammonia based chemistry of HC-110.
    You lose most of the advantages of a monobath by the time you've gotten
    there -- yes, I suppose I could slow down a rapid fixer to take, say,
    6-8 minutes to clear (which would push into the twenty minutes full
    fixing time range) by diluting the concentrate 1:100 (or so), but then
    I'd need to process a single 35 mm film in a quart tank to ensure
    adequate fixing capacity -- and I'd have to stand there and agitate for
    twenty minutes plus wash. I prefer the fast monobath; I can be hanging
    the film long before I'd be ready to wash with a 20 minute soup, but
    might still need/want to tweak alkalinity a little to speed up
    development and lose less of the shadows due to fixing them away before
    they can develop. It's a fine balancing act between excessive contrast
    from overdevelopment and loss of shadow detail due to premature fixing;
    it might be easier to accomplish with raw chemicals (I could probably
    make a PQ based monobath as active as HC-110 A, but leave out the
    solvent developer ingredients and trust that to be taken care of by the
    thiosulfate) but I don't have everything to work with raw chemicals yet
    -- mostly, the chemicals.

    --
    I may be a scwewy wabbit, but I'm not going to Alcatwaz!
    -- E. J. Fudd, 1954

    Donald Qualls, aka The Silent Observer
    Lathe Building Pages http://silent1.home.netcom.com/HomebuiltLathe.htm
    Speedway 7x12 Lathe Pages http://silent1.home.netcom.com/my7x12.htm

    Opinions expressed are my own -- take them for what they're worth
    and don't expect them to be perfect.
     
    Donald Qualls, Jun 23, 2004
    #25
  6. Beppe Alborè

    Dan Quinn Guest

    Your example is the first I've ever heard of an off-the-shelf
    developer being used as a monobath. Good going and so simply
    accomplished.
    You should try that with S. Thio. The NH4 plus S2O3 all eat away
    at image silver. P. Dignan states that A. Thio. is 7 to 10 times
    as fast as S. Thio. I do not believe that applies to the iodide
    because NH4 has little affinity for silver when iodide is
    present. S. Thio. is a best chance for a time delay.
    Also you should give bakeing soda, the bicarbonate, a go.
    I think it as strong a base as ammonia.
    Time may be a factor in your mind but not so for me. All my
    chemistry is Homebrew. I keep monobath processing in mind
    for a try one of these days. Dan
     
    Dan Quinn, Jun 24, 2004
    #26
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