fixer questions (c-41/bw)

Discussion in 'Color: Film, Paper, and Chemistry' started by jbl, Jan 14, 2012.

  1. jbl

    jbl Member

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    I have a few questions about fixer (both C-41 and black and white). I'm posting here because it seems a bit more focused around C-41 fixer.

    1) On the black and white side, I'm using Kodafix sort of accidentally, but I've got a bunch of it left, so I figured I'd keep using it until I run out. According to the bottle, the capacity is 20 rolls of 135-36 per quart if you use a stop bath (which I do), but I seem to get about 12-14 rolls pretty consistently using a hypo-check. With the latest batch of fixer, I did 12 rolls of Tri-X (all EI 320 or 400) over 2 months. I was developing rolls 13 and 14 (in this case, P3200 at EI 3200) and the fixer tested bad before I fixed. I fixed anyway and just added some time.

    My question here is is this normal, i.e. is the difference in capacity between what the bottle says and what hypo check says usually that drastic?

    2) On the C-41 side, I use the Rollei kit which has a separate bleach and fixer. According to those instructions, 500ml of fixer can handle 10-14 rolls of 135-36. Is that realistic given my experiences with black and white? I know the fixers and films are different, but I'm curious why the I should trust the C-41 numbers when the black and white numbers are so far off. Does hypo check work for C-41 fixer?

    3) How similar are the two fixers? Note: I'm *not* wanting to use the two interchangeably, I know that doesn't work, I'm just curious about the differences in the process/chemistry. The MSDS for Kodafix list ammonium thiosulfate as the primary ingredient. The MSDS for the Rollei fixer lists both ammonium thiosulfate and dinatriumdisulfit (my German isn't good enough to know what that actually is).

    4) Generally, can I combine the two fixers for purposes of disposal? I know that may have something to do with local regulations, but when I take bottles to the hazardous waste disposal place, do I need to separate them. Ultimately, I think the thing they care about is the silver and that's not going to be different between the two (I think). Of course, if they're just pouring it down the drain it probably doesn't matter :smile:.

    Thanks in advance, this is just something I've been wondering about.

    -jbl
     
  2. Photo Engineer

    Photo Engineer Subscriber

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    Fixers can vary in capacity due to the amount of silver halide in the films you are using. They also can vary based on the nature of the silver halides in the films. A high speed, high silver film will tax the fixer more strongly than a slow speed fine grain film.

    Color fixers generally have 1/3 the capacity of B&W fixers due to the higher silver halide load in the color films. I would err on the side of caution.

    You can mix any fixer for disposal purposes. Your local laws or regulations will determine what is to be done due to the silver content in the fixers. There should be no other serious restriction.

    PE
     
  3. brucemuir

    brucemuir Member

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    I'll piggy back with a related question.

    Will the b/w fix liquid hypocheck (I believe it's iodine based that turns cloudy when fixer gets exhausted) work with C41 fix?

    I generally do a leader test for clearing with film but not always.
     
  4. Photo Engineer

    Photo Engineer Subscriber

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    Yes, hypocheck will work but it is a very subjective test. You have to learn how to live with it! :wink:

    PE
     
  5. jbl

    jbl Member

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    PE, what do you mean by "subjective"? Does it cry wolf early?

    -jbl
     
  6. Photo Engineer

    Photo Engineer Subscriber

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    The fixer test using KI can cause a yellow precipitate to form. Some is tolerable, but at some point the yellow color means that the fixer is bad. A time to clear tests is IMHO more indicative of the state of a fixer. For that reason I keep small snips of 35mm film here to test my fixer before use.

    PE
     
  7. MattKing

    MattKing Subscriber

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    I use T-Max snippets for that purpose, even when I'm shooting Plus-X. I also carefully track the number of films I fix, and stop using it when I'm at 2/3 published capacity.

    I figure that it is best to use "worst case scenarios" as my testing guide.