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  1. #21
    Ole
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    Not crystals, anhydrous. From http://www.vwr.com - international lab and chemical suppliers.
    -- Ole Tjugen, Luddite Elitist
    Norway

  2. #22

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    Quote Originally Posted by pnance
    When I buy it I have to pay to ship water around.
    If you are in the US, 60% solution (usually contains 1% or so of sodium thiosulfate as well) is probably better choice. It's more stable. Also, making anhydrous powder requires additional step and energy than making 60% solution. Shipping in the US is pretty cheap. (The price of ammonium thiosulfate from some photo chemical sources is not very cheap, btu that's another story.)

  3. #23

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    Quote Originally Posted by Ole
    So far, I have seen no ill effects of this. Developers have been Neofin, rodinal, FX-2, Beutler's, and Pyrocat-HD.
    I see, your developers are all very dilute ones, and that might be a factor. If anyone tries this technique with more concentrated developers, like XTOL, DS-10, Microdol-X, Perceptol, D-76, Ilfotec DD-X, Microphen, D-19, DK-50, etc., I'd be very cautious to run a test film first (or use more conventional technique).

    I remember when I was making DS-10. I was adjusting the balance between fine grain effect and developer activity and I had to settle at a point to avoid dichroic fog problem with some films. (I could get dichroic fog if I increased sulfite! If I added thiosulfate or thiocyanate, I would get dichroic fog with many films!)

    It's a bit off topic here, it's also related to grain size. In a very general term, if the developer contains much sulfite, but if the development kinetics is adjusted properly, you get fine grain effect without much loss of accutance (eg XTOL). But if you increase the rate of development, then the grain size grows due to rapid physical development in addition to chemical development. (Physical development is more active in more active developer solution, especially in well exposed areas of the film.) So, if the developer is more concentrated than yours, it's possible that the addition of ammonium thiosulfate can cause problem with some films.

  4. #24
    Ole
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    Ryuji, I think you're right.

    I started doing it this way when I did a stupid mistake: Started developing in Neofin, then discovered I'd dumped my fixer after the last time I used it. But then I realised that the difference between the alkaline fixer I often use and the spent neofin (assuming it to be close to Beutler's) was mainly the thiosulfate. So I quickly dissolved a little ammonium thiosulfate in a little water, and dumped that in as soon as the developing was done. The results were so good that I've kept doing it since.

    One benefit is that the fixer is always fresh, which is great for someone like me who does "batches" every month or so. In the summer I go through a lot of films, but in the winter thing tend to die from old age before I have a film to develop. Winter on the other hand is printing time, so I go through a lot of paper fixer.

    I know that the "tip-in" method works with very dilute developers, and I have reason to believe it might well give unwanted side-effects with more concentrated developers. I haven't tried it, but I have used "related" systems which I didn't like at all.
    -- Ole Tjugen, Luddite Elitist
    Norway

  5. #25
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    Ole, a 'cupful' of solid ammonium hypo can be a lot in relative terms depending on how much developer you have. A normal fixer may contain about 120 g/l of ammonium hypo and do a good job fixing. Sometimes less is used.

    So, you might want to optimize the amount to save money.

    Another thing to be aware of is that ammonium hypo solid is not noted for its shelf life. That is why it is produced mainly as the 60% solution. As you keep the solid, it will tend to decompose into various sulfur compounds and ammonia.

    PE

  6. #26

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    Quote Originally Posted by Ole
    One benefit is that the fixer is always fresh, which is great for someone like me who does "batches" every month or so. In the summer I go through a lot of films, but in the winter thing tend to die from old age before I have a film to develop. Winter on the other hand is printing time, so I go through a lot of paper fixer.[...]
    In terms of processing capacity and other factors, I think an alkaline fixer with conventional usage is most economical and least wasteful. I use my house formula, which is buffered at pH 7.5 to 8 range. The benefit of this pH range is that the fixer washes out very fast, and that the fixer has a very long shelf life even after partial use. You can keep a working solution for a year very easily. Another difference with my buffered fixer is that it can be used with acid stop bath with no problem. I can add quite a bit of acetic acid before this fixer becomes acidic enough to affect rapid washing and long keeping properties. The base buffer in the fixer also neutralizes acid in the emulsion layer and paper base quickly, and so the fix washes out fast, whether acid stop or water rinse is used.

    While I reuse film and paper fixer, I check the exhaustion level with standard iodide precipitation test. It's pretty safe to use *rapid* fixer until iodide test results in permanent creamy precipitate, as most films fix perfectly well in 4-5 minutes at that point (tested with standard sulfide test). Delta 400 may take an extra minute or two. Also, regular sodium thiosulfate fixer craps out quite a bit earlier than ammonium thiosulfate.

  7. #27
    Ole
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    Quote Originally Posted by Photo Engineer
    Ole, a 'cupful' of solid ammonium hypo can be a lot in relative terms depending on how much developer you have. A normal fixer may contain about 120 g/l of ammonium hypo and do a good job fixing. Sometimes less is used.

    So, you might want to optimize the amount to save money.
    Oops - I must have misquoted myself!

    My "regular" usage is three teaspoons of ammonium thiosulfate in half a cup of water. Less water if I do two 35mm films in a Paterson tank, just to make it fit in there. About 25 g/liter of developer is more than enough.
    -- Ole Tjugen, Luddite Elitist
    Norway

  8. #28

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    Quote Originally Posted by Ole
    About 25 g/liter of developer is more than enough.
    Well, that's a good one. Add 25 grams of
    anhydrous Ammonium Thiosulfate to each liter
    of developer. I sound tame suggesting 20ml of A.
    Thio. concentrate per roll to whatever solution
    volume of fixer needed. Dan

  9. #29
    Ole
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    That's 20ml of 60% solution, or 12g per film. Half a liter developer for a roll of film? it's in the same range - my Paterson tank uses 500ml for a roll (120 or 220) of film. You end up at 24g per liter, I use about 25g...
    -- Ole Tjugen, Luddite Elitist
    Norway

  10. #30

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    Quote Originally Posted by Ole
    One of my "perversions" is that sometimes I use no stop at all, nor "fixer".

    Instead I dump a cupful of 50% ammonium thiosulfate straight into the developer when I want to stop it.

    Within 10 seconds the film has been fixed enough that no further development can possibly take place.

    It works; but don't do it just because I said it works!
    The earliest reference to this technique of which I am aware was in the documentation for FR X-22. They mention adding a portion of their Instant Fixol to replace some of the developer to stop development and fix the film.

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