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  1. #21
    greybeard's Avatar
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    Bethe,

    Your description of the deposits being unaffected by acetic acid brought something to mind, although I haven't been able to track down any supporting evidence: the material you are seeing could be an insoluble sulfur compound, possibly calcium sulfite. Elemental sulfur can also be precipitated by acid (as in stop bath) reacting with thiosulfate (fixer) in the absence of a high sulfite concentration.

    It might be worth checking to see if your water does in fact deposit only salts that can be removed by dilute acid: put a few drops of water on a piece of blank film, let it dry, and then try washing it off with both plain water and with vinegar (do the same thing with distilled water, as a control, in case your distilled water is not really clean). I have a hunch that you will discover that the problem is not due solely to the hardness of the water.

    It would be nice if someone with a better command of photographic chemistry could weigh in on the possible origins of insoluble sulfur complexes; I'm pretty sure that I've seen it before (in connection with EDTA additions to photographic formulas) but this really isn't my field and I don't have easy access to the literature.

  2. #22
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    It might be worth checking to see if your water does in fact deposit only salts that can be removed by dilute acid: put a few drops of water on a piece of blank film, let it dry, and then try washing it off with both plain water and with vinegar (do the same thing with distilled water, as a control, in case your distilled water is not really clean). I have a hunch that you will discover that the problem is not due solely to the hardness of the water.
    Thanks - I've started trying a variation of this and I'll try this as well. I think you're right that there's more to this than just hard water. I may also send a sample to a testing facility in case I need to do anything to it for the whole house as well. The RC prints I did last week (with distilled only to make the developer) are fine. Maybe there's even something wrong with the softener.

    Thanks all! I'll keep experimenting and let you know what works.

  3. #23
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    My well delivers much limestone in the water, especially after a good rain. A 5 micron filter helps, although it doesn't block limestone disolved in the water. I let the filtered water stand for perhaps weeks, and then siphon off all but the bottom inch or two of the storage jugs for use. The water is finally run through a coffee filter. Despite this, I still use distilled water for diluting chemicals and for the final rinse with Photo-Flo. This use of distilled water adds very little to the cost of processing of film. Prints are washed in the filtered well water, and surface moisture toweled off before hanging to dry.

  4. #24
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    What soluble compound of calcium or magnesium might be in water? The hydroxide is somewhat soluble. The carbonate is formed in caves when water containing some of the hydroxide comes in contact with CO2 in the atmosphere. Over years, stalactites and stalagmites are formed out of limestone. When you mix carbonate developers with hard water, you get cloudy developer from the calcium and magnesium hydroxides. You will see it very soon after mixing. Many commercial developers incorporate a chelating agent to keep the limestone from precipitating. If you mix a little sodium carbonate with your water, you will see the cloudiness form. It is true that the sulfites are also insoluble, so you should also get a precipitate by adding a little sodium sulfite to the well water.

    I have mixed developers in my hard water with no problems except the cloudiness, and I have not seen that to cause any processing problems. If I must use carbonate, I prefer to use a chelating agent with it, but most of my developers work with borax, Kodalk, TEA or even sodium hydroxide, none of which cause the calcium to precipitate.

    I do not use photo flo. I have done, but no longer do. It does just as well to wipe the excess water from the negatives with a paper towel or a well-used and soft cotton towel. Baby's diapers would be good if I could still get them. If you tell me I will ruin my negatives, I will tell you I have never ruined any by this treatment. It has been years since I ran into an emulsion that was soft enough to be scratched by a soft towel. It has also been years since I ran into any kind of water marks on my negatives. I also dry them with a small electric hair dryer. Does this confession mean I will be excommunicated?
    Gadget Gainer

  5. #25
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    Oh I sincerely hope not! I put the negatives still in the holders in a pvc tube with a hair dryer on fan (no heat) to dry the negatives. Works like a charm, but I also rinse them in photoflo first. I just shake the excess water out first. I'm on a well with hard water, but we have a filter that takes most of the hardness out.
    If I had been present at the creation, I would have given some useful hints for the better arrangement of the Universe.
    Alfonso the Wise, 1221-1284

  6. #26
    greybeard's Avatar
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    gainer: What soluble compound of calcium or magnesium might be in water? The hydroxide is somewhat soluble. The carbonate is formed in caves when water containing some of the hydroxide comes in contact with CO2 in the atmosphere. Over years, stalactites and stalagmites are formed out of limestone. When you mix carbonate developers with hard water, you get cloudy developer from the calcium and magnesium hydroxides. You will see it very soon after mixing...

    This is close, but maybe not quite right---limestone is calcium carbonate, essentially. Carbon dioxide from or decaying vegetation (or other sources, such as volcanoes) dissolves in water to form carbonic acid, which dissolves calcium carbonate by converting it to calcium bicarbonate, a substance that is much more soluble. In caves, the lower carbon dioxide concentration in the air allows the reaction to go the other way, releasing carbon dioxide and precipitating the carbonate as limestone again. Calcium in water is usually due to a high bicarbonate concentration, which is why boiling it causes a precipitate of calcium carbonate to drop out (the so-called temporary hardness). Calcium hydroxide is much more soluble than the carbonate, but reacts with carbon dioxide until the carbonate/bicarbonate equilibrium is reached; this is the basis for the "limewater" test for carbon dioxide (make limewater by saturating water with calcium hydroxide; bubble your breath through it and the carbon dioxide will cause calcium carbonate to precipitate out)

    Magnesium sulfite seems to be reasonably soluble, but the sulfate (Epsom salts) and chloride are very soluble. Of all the possible culprits, it seems that calcium sulfite would be the only thing that could arise from well water and not be soluble in acetic acid; it seems that Bethe's problem might be sulfur caused by bad chemistry, or some sort of soap formed by organics in the water, alkali from the developer, and calcium or magnesium. What is odd is that most of the potential culprits should form precipitates in the solutions, and not streaks on the film at the drying stage. The metallic soap (aka scum) idea is motivated in part because it would probably adhere preferentially to naturally hydrophobic surfaces, like the non-emulsion side of the film.

    We really need a photographic chemist in this discussion!

  7. #27
    gainer's Avatar
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    Maybe some of the stuff you put in dishwashers to prevent soapscum on the dried dishes would help, at least to identify the problem.
    Gadget Gainer

  8. #28
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    it seems that Bethe's problem might be sulfur caused by bad chemistry,
    I would think sulfur would be yellow. All the chemistry was brand new and familiar.
    After some experimentation (if you don't like wiping negs, please stop reading here), I discovered that a wipe with a very lintless soft cloth with vinegar on it, then a wipe with distilled water will remove the residue. Yeah, I know it's more contact than many are comfortable with, but I tried soaking and non-contact measures and they didn't work.
    I think what it is is just very stubborn limescale (basically calcium carbonate). I've never seen any as stubborn as what I have to clean off the shower, and this is probably the same stuff. Chances are, I washed for too long with the well water and probably will make all the chemicals with distilled next time, too (not just the developer). The soaks in distilled and even vinegar just weren't quite enough action to remove the scale, but slight pressure works. I haven't done all the frames (I tested with a few end ones), so I'll do that next. If they aren't printable with the residue, then wiping isn't losing me anything anyway.
    And if I were still at the lab, I could test it and see what it is pretty easily. But noooo, that would be too easy.
    Thank you all! I'll let you know how it goes!

  9. #29

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    Quote Originally Posted by gainer View Post
    What soluble compound of calcium or magnesium might
    be in water? The hydroxide is somewhat soluble.
    The bicarbonates are both much more soluble than
    the carbonates. If there is a source of the calcined
    forms, and that very unlikely, then the hydroxides
    may be present. Dan

  10. #30
    gainer's Avatar
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    Just for the record, sulfur has two crytal forms, one of which is yellow and the other pale yellow. The amorphous form is also pale yellow. A very thin layer of either of the pale yellow forms might be indistinguishable from white, especially under incandescent light.
    Gadget Gainer

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