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  1. #1

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    Easy-measure Fixer

    I got tired of weighing out the ingredients for fixer. It was tedious, and I often wasn't real careful about it. Fortunately, fixer ingrediant proportions aren't really all that critical. In any case, I decided to try a volumetric approach. It works well enough, and it's a lot easier. This fixer is based on Kodak F-34, but the proportions are not quite the same. The pH measures 6.5 at 18C. If you want to raise it a little, increase the sodium sulfite to 1-1/2 tsp. (teaspoons).

    I like to premeasure the dry ingrediants and store them in old 35mm film cannisters until I need to mix up some fixer. Then I add the premeasured contents to the ammonium thiosulfate solution. A film cannister will hold enough for 2 liters of fixer.

    Ammonium thiosulfate (60%) 3/4 cup (200 ml)
    Water to make 33 fl. oz (1 l)
    Sodium metabisulfite 1 tsp (12.6 g)
    Sodium sulfite (anh) 1 tsp (8.8 g)

  2. #2
    Bruce Osgood's Avatar
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    Easy-measure Fixer

    Ammonium thiosulfate (60%) 3/4 cup (200 ml)
    Water to make 33 fl. oz (1 l)
    Sodium metabisulfite 1 tsp (12.6 g)
    Sodium sulfite (anh) 1 tsp (8.8 g)


    I like the idea of premixing the dry and holding in film canisters.

    I'll be using Arm & Hammer wash aid (Sodium sulfite - mono). Do you know if the increase from anh to mono is 15% (8.8 x 1.1765 = 10.4)? Any feelings for capacities with Fiber Base papers?

    Thanks,

  3. #3
    juan's Avatar
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    Bruce, the Arm and Hammer is sodium carbonate, isn't it?
    juan

  4. #4
    Bruce Osgood's Avatar
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    Quote Originally Posted by juan View Post
    Bruce, the Arm and Hammer is sodium carbonate, isn't it?
    juan
    IT SURE IS!!! IKES, I've done it again.... Thank you Juan.

  5. #5

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    While I am not trying to interfere with the idea of inexactness here (this is why I like customary units so much), let me point out that it is unfortunate that you have picked units (cups and teaspoons) that have at least four commonly-used units each depending on system or the size of the cup, although the metric equivalent for cups does seem to indicate the U.S. 8-fl.-ounce definition of a cup.

    Are you using U.S. teaspoons or the metricized versions that are making rounds? It'd be best to give the metric equivalent of the size of your teaspoon just so as not to introduce variables.

    There's also differently sized UK, Australian, and Canadian teaspoons, some 1/3 of a tablespoon, some 1/4, so this unit is particularly messy.

    Also, as a final nitpick (sorry!) the Liter is closer to 34 U.S. fl. oz. than 33 (33.8 and change)

  6. #6
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    I'm afraid that Karl is right about all of the variants in these kitchen measurements. This has been my objection since the very start.

    It is especially bad when one considers the fact that different forms of the same compound such as powder and crystal vary by 20% in weight when measured by volume.

    This can be a calamity with developers but not very harmful with fixers unless one does not test for hypo and silver retention to get the right archival wash conditions.

    Then, it beomes a calamity again!

    PE

  7. #7

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    That looks a lot like Ryuji Suzuki's recipe:

    Neutral Rapid Fixer

    Ammonium thiosulfate 120g
    (or 60% solution 200 ml)
    sodium sulfite 15g
    sodium metabisulfite 5g
    water to make 1.0 liter
    target pH 7.0 plus/minus 0.5

    This fixer gives rapid fixing and rapid washing, same benefit as what's claimed for alkaline fixers, but with minimum of swelling.
    Suzuki
    Tom Hoskinson
    ______________________________

    Everything is analog - even digital :D

  8. #8
    Photo Engineer's Avatar
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    The original near-neutral pH fixes have been known for years. Such fixes have been patented by Kodak and others for a variety of benefits. The optimum pH range is 6.2 - 6.7 as disclosed in the literature, but some move it to pH 7.0 for one reason or another.

    PE



 

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