Urgent question RE fixer concentration

Discussion in 'B&W: Film, Paper, Chemistry' started by Andrey, Jan 5, 2014.

  1. Andrey

    Andrey Member

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    I've just started developing two films which I've been shooting all of last month.

    Then I drop a piece of film to test the fixer and it goes clear with agitation in 10 seconds.

    The developer I mix myself, but I'm using fixer from a photo club which usually was supplied as working solution.

    I usually don't agitate fixer when I test it, but it seems like a very fast time to fix. I don't want to end up with clean negs or no shadow detail and I don't have any other fixer now... and it would take a while to get. (a week)

    How would you adjust to working concentration? Or am I overthinking this?
     
  2. MattKing

    MattKing Subscriber

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    Dilute the fixer solution 1 + 3 and do another clip test.
     
  3. Tom1956

    Tom1956 Inactive

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    I'll believe 10 seconds, as long as it wasn't T-max, and the fixer was fresh. Keep in mind that higher concentrations of hypo can actually fix more slowly, if you can believe Aaron Sussman, Amateur Photographers Handbook.
     
  4. Andrey

    Andrey Member

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    Well... thanks for the replies. 1+3 dilution didn't clear the strip in 3 minutes.

    I ended up diluting it a bit and the negs are ok, but not very dense. I'm still adjusting for this film/dev combo. Should be a nice Dmax for scanning. lol
     
  5. Doremus Scudder

    Doremus Scudder Member

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    A "working solution," by definition, is already diluted correctly. Use it as is. If you are mixing from the concentrate or from powder, follow the manufacturer's instructions for mixing and diluting to a working solution.

    As for clip tests: yes, some film clear very quickly in fresh fixer. I know that common wisdom is to fix for twice the clearing time, however, 20 seconds of total fixing time is just too little. There are those who recommend at least three times the clearing time plus a bit of a safety factor to account for the slowing down of the fixer activity during the actual fixing process. (Do a clip test before fixing a large batch of film and then immediately after; the second clearing time will be longer.)

    Add to this the fact that modern films use harder-to-fix silver compounds and complexly bound sensitizing dyes which require more time in the fixer, and you can see that using the minimum 2x-clearing time is risking under-fixing.

    Film is not adversely affected by somewhat longer times like fiber-base paper since it is coated on a waterproof substrate. Longer will not hurt and ensure 1) proper fixing and 2) that all the sensitizing dyes get dissolved out (really one in the same thing. Use the manufacturer's maximum recommended fixing time as a standard. Using this time will not damage or bleach your negatives in any way. Do the clip tests to find out when your fix is exhausted.

    If you are really interested in fixing for optimum permanence, look into two-bath fixing.

    If your negatives are clear or too thin, it's not your fixer that is the problem; that lies in exposure and development.

    Best,

    Doremus
     
  6. Andrey

    Andrey Member

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    Thank you Doremus

    The (relatively) thin negs were because I metered ambient handheld like I would for digital color. Next time I'll to add a stop to what the meter tells me when shooting faces to make em brighter and get more shadow detail.