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  1. #11

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    I find my Ilford Hypam fixer is slightly pink after using Tmax film. The color fades with time. I assumed it dye from the film, and nothing to do with the actual fixer.
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  2. #12

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    Quote Originally Posted by Nick Kanellos View Post
    I posted this question in another forum, but I thought I try asking here.

    I noticed that my fixer (Agfa Universal Fixer) turns pink after a few printing sessions. When I checked the ingredients on the label, they are Ammonium Thiosulfate and Sodium Sulfite. From what I've read, both are neutral to slightly alkaline when aqueous. The Material Safety Date Sheet states that the PH is about 7.6 - neutral to slightly alkaline. I figured the pink colour is due to the Indicator Stop Bath being neutralized by the alkaline fixer. But doesn't that also mean that the stop bath is acidifying the fixer? I thought fixers like TF-3 and TF-4 where the only ones that were supposed to be alkaline.

    So, given that one of the reasons to use an acid stop bath (when using an acid fixer) is to neutralize any carried-over alkaline developer, is it a good idea to use an acid stop bath, like Kodak's, given that this fixer is alkaline? Anyone know?
    I use a similar fixer, Kodak's C-41 Flexicolor Fixer and Replenisher and have noticed the same thing, but I never gave it a second though. After passing a few prints through the tray, the fixer picks up a decidedly blue/violet color, caused no doubt, by the indicator dye carried over from the stop bath. The fresh working strength fixer has a ph of 6 to 6.5, making slightly acidic, but not acidic enough to keep the dye from changing color. This is not a problem, and the dye will not stain the prints. It will wash out completely. The fixer itself is well buffered, and will maintain it's ph level for a good number of prints - probably more than is consistent with good archival practices. Eventually though, it will start to turn yellow and that's when you'll know that the buffering capacity has been exceeded. An acid fix with hardener, like the powdered sodium thiosulfate Kodak Fixer, will turn yellow after a few prints have gone through. It is acidic enough to maintain the yellow color of the dye.

    Yes, it is a good idea to use a stop bath. The fixer should be buffered well enough to tolerate the small amount of acid carried over from the stop. Carrying active developer over into the fixer will shorten the life of the fixing bath, and may cause some staining on the print.
    Last edited by fschifano; 01-10-2009 at 10:55 AM. Click to view previous post history.
    Frank Schifano

  3. #13

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    I currently use a Citric Acid based stop bath and a neutral fixer both from the same manufacturer. The life in the darkroom now is better. I don't tollerate any more the bad smell from Acetic Acid based products. Anyway I take the habit to cover the trays to reduced bad smell at a minimum level.
    Regarding the prints, all fiber based, they don't seem to have any problem.

    Patrizio

  4. #14
    Ole
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    If the indicator used in the stop bath is Bromophenol blue, it should be blueish purple even in weakly acidic solution. Phenol red is another candidate, but that needs an alkaline solution to change colour properly which doesn't seem to be the case here.

    Personally I can't see the logic behind putting any kind of dye in a stop bath, but then I use either water or a weak solution of citric acid for stop bath. Both are cheap enough to discard after use.
    -- Ole Tjugen, Luddite Elitist
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  5. #15
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    Flexicolor Fix is about pH 6.5 and is not alkaline enough to cause a substantial shift in the indicator color of a stop bath. I have not tested this particular combination, but it should not cause a problem even with a shift.

    Also, the absorber dyes in film contribute to coloring the solutions, so if it happens with film and not with paper, it is the film that is the problem.

    PE

  6. #16
    Ian Grant's Avatar
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    Quote Originally Posted by Photo Engineer View Post
    Flexicolor Fix is about pH 6.5 and is not alkaline enough . . .
    PE
    As Neutral is pH 7 then technically Flexicolor Fix is acidic

    Ian

  7. #17
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    Ian;

    Of course it is. But not all indicators shift at 7. So......

    PE

  8. #18
    Ole
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    Phenol red then, or possibly Bromocresol purple.
    -- Ole Tjugen, Luddite Elitist
    Norway

  9. #19
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    Quote Originally Posted by Patrizio View Post
    I currently use a Citric Acid based stop bath and a neutral fixer both from the same manufacturer. ...

    Patrizio
    Patrizio, I'd be interested to know who the manufacturer is.

  10. #20
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    I would like to warn everyone who uses either a neutral stop or a standing water rinse with an alkaline fix, that the film or paper may fog in the fix itself if you turn the lights on too soon in the fixing cycle. The water rinse must be running water, not standing, and alkaline or neutral stops are just not strong enough to stop development in alkaline fixes, especially with extensive use. They exhaust very rapidly compared to running water or acid stops.

    Therefore, you must not turn on room lights until 2x the clearing time has been reached or you will likely see some fog. I have run this experiment myself and seen a significant dmin increase in prints with standing water.

    What happens is that with standing water, it gradually becomes alkaline with just a tad of developing agent build up. With running water for a rinse, this problem is eliminated. This is explicitly stated in TF-4 instructions. Use running water. The same is likely true of neutral or alkaline stop baths.

    PE

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