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
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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
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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
  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
  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
    Speedway 7x12 Lathe Pages

    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
  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
    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
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