How Much Reuse of Stop Bath and Fixer?

Discussion in 'Film and Processing' started by markdeneen, Oct 27, 2010.

  1. I mix my chemicals into 2L jugs. How many 35mm rolls can I process with a jug of stop bath or fixer? I have been using them for about 10 rolls and then making it fresh. Am I way over, way under?
  2. It depends on the brand and type. I wouldn't risk guessing, but instead look for a data sheet from the manufacturer. The way I look at it is I spend a lot of time and money taking images... why would I skimp or take short cuts for developing them? If you have a very high quality standard for your processing, you will do the right things to ensure proper handling and use of chemistry.
    That said, without knowing which brand chemistry you are using, I would venture to say that stop would be in the range of 20 rolls (if it's indicator stop bath, it will either become purple or clear looking). For fixer, Maybe 15 rolls? With fixer, when it stops clearing the backing layer, or takes a long time to do so, then it's toast. So I think sticking with 10 rolls is safe, but I would search around for the spec/data sheet.
  3. The capacity of the chemicals should be on the box or maybe on the manufactures website. With stop I use it until it turns purple.
  4. Fixer is easy, this is the test that I learned just awhile back. When you first mix it up do a test and see how fast it takes to clear. When you begin to think that it is about all used up do another test. If the test of the used fixer takes twice as long or more to clear then it is time to replace.
    The test. Take a drop of fixer and put it on a piece of film like the leader of a 35mm film that you cut off. Let it sit for 30 seconds. Now drop the leader in to a beaker or cup with fixer in it and see how long it takes for the spot where you placed the drop to disappear.
    I use Kodak fixer, according to the data sheet a Pint will fix about 10 rolls. Some films do require or exhaust the fixer more than others so I begin testing at roll 8. If it does not pass then I mix up another batch and then test to get the baseline then process my film.
    Some stop baths have an indicator in it that shows up under a safe light. If it clouds or turns dark then it is spent. I use Kodak stop bath and it is pretty cheap, if I feel that it is spent, I will turn off the lights and turn on the safe light and check it out. A bottle of concentrate will last quite awhile.
  5. I am using Kodak Indicator Stop, and Kodafix.
    My Stop turns greenish yellow pretty quick and gets more lurid as I go. The fixer seems "clear" after 10 rolls. I haven't seen it turn purple.
    Clay - I'll try that - thanks.
    BTW, all my rolls have processed "as expected" with no weird results. So, on that basis I guess I wasn't too far off. I just didn't want to be wasting money if it was good for like 100 rolls and I was tossing it at 10!
  6. I work on the basis of 30 rolls of film per 2 liters of fixer.
    If you're in doubt you can check easily. Pour some fixer into a glass and put the leader of a film roll into the liquid. If it turns translucent and clear in less than 5 minutes the fixer is good; longer than 5 minutes means it needs some replenisher, or full replacement if you prefer.
    For best results the fixing time you use in processing should be twice the clearing time in the test. This gives a very healthy margin.
    Someone showed me this in 1984 and it's proved infallible ever since. Never had a problem with under fixed film since then.
    EDIT - Apologies to Clay who I just noticed recommended nearly the same thing.
  7. You need to be careful with the fixer test that Clay described. It's a good test, and it's one that I use myself, so I can heartily recommend it. Any film will do for the test, but you must use the same type of film for the test every time or else the test is invalid. Clearing times are not the same for films of different brands and/or speeds. Perhaps the most dramatic example is to be had by comparing one of the Foma Pan films to one of the T-Max films. In completely fresh rapid fixer, a piece of Foma film will clear in around 30 seconds at room temperature. TMax films will take a at least a couple of minutes under the same conditions. You can see the kind of incorrect assessment of a fixer's condition that can lead to. You don't need much film to do the test. A single square inch will suffice, and I suggest you sacrifice a roll of your cheapest, nastiest, most outdated film as test material. As long as you use from the same roll each time, the results will be a reliable indicator.
  8. Depletion of the stop bath depends on the developer and how much is carried over into the stop bath. The simple answer is to use indicating stop bath, which changes color when the acetic acid is depleted (the pH goes up).
    Fixer usually comes with recommendations on the number of rolls which can be processed. This can be variable. You can test fixer with a 1% solution of silver nitrate. A drop of this test solution will remain clear if the fixer is active, but cloud up if depleted. If the cloudiness clears within a second or two, you are on the edge.
  9. James G. Dainis

    James G. Dainis Moderator

    They used to sell small bottles of fix indicator solution which I imagine was the 1% silver nitrate that Edward mentions.
  10. Thanks for that tip Frank. I guess I got lucky for the last little bit as both the films that I have been using most often clear in about the same amount of time. But now I am out of both of them with almost no possibility to acquire them again. Arista II being one of them.
    The fixer check solution is available from Freestyle, it is called Hypo Check. There are other brands of it one of them I believe is Edwal Hypo Check.

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