De-ionized water: safe for photo use?

Discussion in 'B&W: Film, Paper, Chemistry' started by bernard_L, May 8, 2013.

  1. bernard_L

    bernard_L Subscriber

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    Yesterday at the supermarket there was de-ionized water (for household irons) on sale at 1€/5Litre, about half the price I'm used to. I was about to grab a few, but then reading the label gave me pause: "not fit for drinking", "keep out of reach of children". So, what stuff could there be in that water that is unfit for humans (apart from the fact that it's not good to dring mostly water that is too soft)? and could it be unfit for photo chemistry?
    Notes:
    - I use (so far) de-ionized water (a) for final negative rinse because tap water contains particulate matter and I've not gotten around to install an in-line filter (b) for mixing negative developer, just to be on the safe side.
    - Here I'm talking about de-ionized water for household irons, not the high-tech stuff used in semiconductor fabrication labs.
    - Where I live (France) de-ionized water is a commodity, normally at 2€ for a jug of 5 liters. I never saw distilled water on store shelves. From previous threads on related subjects, it seems that the situation in the US is different, with distilled water being available and cheap.
    - Valuable insight is given by dancqu in the thread www.apug.org/forums/forum37/38455-distilled-water-question-4.html (emphasis added):
    But that does not really answer my question.
     
  2. Tom1956

    Tom1956 Inactive

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    I use plain distilled water from the grocery store. About 95¢ a plastic gallon jug. As far as I know it's de-ionized. And I drink it sometimes. Doesn't taste like anything because nothing is in it.
     
  3. Gerald C Koch

    Gerald C Koch Member

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    "Not fit for drinking", etc means that the water is not guaranteed to be free of pathogens. But it is fine for photo purposes.
     
  4. K-G

    K-G Subscriber

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    De-ionized and distilled water will change the salt balance in your body. I don't know how much a harmfull volume is but the recommendation is not to drink it. For photographic purposes it should be just fine and for some applications it is even recommended. Use it and enjoy the low price. Here in Sweden it is difficult to get it for less than 4 - 5 € for 5 liter.

    Karl-Gustaf
     
  5. cliveh

    cliveh Subscriber

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    De-ionized water is fine and I have been using it for years for a 30 second dunk after the wash. No photoflow, no wetting agent, just de-ionized water. I never have any drying marks.
     
  6. DREW WILEY

    DREW WILEY Member

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    Deionized and steam distilled are not the same thing. For critical use, I'd only opt for the latter. And since they cost exactly the same in the
    supermarkets around here, there's no sense getting anything but the real deal. Our tap water here happens to be quite good, so works perfectly well for ordinary developers, fixers, etc. I always use true distilled for the final film rinse, or during heavy storms when they might
    add some excess chlorine to the tap water, or for anything potentially fussy like stock dev or dye concentrates sensitive to either pH or
    organics. Ironically, the "drinking water" from the same bottling companies is basically tap water which has first been deonized and had the chlorine taste removed, then has certain minerals selectively added. Seem that pure water tastes odd to most people.
     
  7. cliveh

    cliveh Subscriber

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    Can you please explain how using the real deal will improve my negatives?
     
  8. michael_r

    michael_r Subscriber

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    Funny you mention this, Drew. Just the other day it occured to me in all the years using either deionized or distilled water from the supermarket to mix photo chemicals, chemistry classes in college, high school etc., I had never tasted it. So after mixing up some chemicals I decided to swig the last bit left in the bottle of steam distilled. Bleah! Turns out while we think of H20 as having no taste, I guess the water I'm used to drinking must have a taste (due to dissolved salts, ions, whatever) so actual pure tasteless H20 tasted terrible. If that makes any sense. It's not only the taste, but the "texture" (? not easy to describe) that was weird. I suppose that could be because the water I'm used to drinking - either tap, or bottled (Evian, Naya, Nestle) is slightly alkaline versus neutral steam distilled.
     
  9. Tom1956

    Tom1956 Inactive

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    Agreed on the taste and "texture" of distilled water. At the same time comical, to be questioning plain 100% pure distilled water as if it were poison. And if any of us were to guzzle 4 gallons of it in a day, we would either burst open, or spend the whole day behind a tree. And that would be about the worst of it. But photographic chemicals would love it. Contamination-free. Haven't we all got enough other variables? My policy is all developers get mixed in distilled water. That's the 1 chemical that you don't want to risk contaminating.
     
  10. bernard_L

    bernard_L Subscriber

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    Thank you all for your comments. I agree it should be OK. But what if the process to produce that bargain de-ionized water (see my OP) has exchanged the ions that the steam iron doesn't like (Ca, Na) for other ions that offset the RedOx balance, for instance. Some picture-taking opportunities happen only once...
    So, I'll buy one, and do an A/B comparison (water "x" versus usual one) with HC110 dilution H, which, being high dilution, should be most sensitive to water quality.
     
  11. dorff

    dorff Member

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    RedOx is something else, involving a change in oxidation state of at least two and possibly more atoms or groups. When water is purified with de-ionisation, the positive ions (cations) are replaced with H+. This is done by presaturating a cationic resin with an acid such as HCl. When the water is then contacted with it, the sodium, calcium and other positive ions replace the H+ in the resin, and the H+ goes into solution. The opposite is also done, by presaturating an anionic resin with an alkali such as like sodium hydroxide. The OH- anions in the resin are then displaced by the anions such chloride Cl-, sulphate SO4-- etc. As you probably already know, H+ and OH-, when they come together, produce H2O. So the net result is pure water. Ion exchange is not a redox process, as the charge on the ion doesn't change and its composition doesn't change. It is only its dancing partner that changes.

    Reverse-osmosis is essentially filtration at a molecular level. Water is forced at very high pressure through a membrane with pores sufficiently large to let water permeate, but not large enough to allow most ions to permeate. Because of their charge, ions have a larger diameter and may be repulsed by selective membranes. The permeate is pure, and the retentate contains a higher concentration of dissolved substances. A practical setup for homes is to use the pipe pressure to do the work, and collect the permeate at a slow rate. The retentate remains in the supply line and will still be fine for bathing, dishwashing etc. The rate at which RO works at these lower pressures allows only a few gallons a day to be purified, but that is usually more than enough for photographic and other home use. The guys who breed tropical fish in 200L tanks might need a larger system. Incidentally, that is also a good place to look for an affordable RO kit.

    All the processes to purify water are in one way or another energy, waste and/or cost intensive. In ion exchange, the two waste streams of acid and alkali used to condition the resins can be extensive. In RO, a lot of pumping energy is required to get the water through the membrane, and the membranes are expensive. In distillation, the latent heat of evaporation must be expended in the form of heating or vapour recompression, the latter being more energy (or rather, exergy) efficient. RO is best at removing everything including organics. Distillation is best at producing pathogen-free water, but cannot remove all organic volatiles. So for photographic use, I'd say RO is your best bet. Where I live, we pay ZAR 0,80 per liter. That is about $0,45 per 5 liters. It makes sense to use it for all photographic use other than washing, so I do not really ponder it much. I keep a 20 liter tank with a tap, and top it up with water from our local "fountain" where they fill 5L bottles for ZAR 4 a piece. Our local tap water is dodgy at times, and of course produces very significant drying marks. So the final rinse is always in purified water.
     
    Last edited by a moderator: May 9, 2013
  12. Doremus Scudder

    Doremus Scudder Member

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    Funny that you can't find distilled water in France. Here in Austria it is readily available and carries a label in both German (destilliertes Wasser) and Italian (acqua destillata). It's what I use for the final rinse with photoflo. Five liters is under 2 euros.

    De-ionized water, however, will be fine for your purposes as well. If that's all you can find, use it.

    Best,

    Doremus
     
  13. Ian Grant

    Ian Grant Subscriber

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    Distilled water is no better than De-ionised for photographic use and in most areas tap water's OK as well, - there's really only issues in hard water areas.

    Ian
     
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  15. Sal Santamaura

    Sal Santamaura Member

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    Anyone who's mixing XTOL stock using soft tap water of unknown iron content is asking for trouble. Mix XTOL stock using distilled (not "de-ionised," but "prepared using steam distillation") water. Store it in full glass bottles. Enjoy the benefits. See:

     
  16. Ian Grant

    Ian Grant Subscriber

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    I used Xtol and soft and hard tap waters for many years, replenished, from it's release until about 5 years ago, never had a problem. The issue is iron content of the water.

    Ian
     
  17. Sal Santamaura

    Sal Santamaura Member

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    Which is why I emphasized the unknown iron content of tap water, regardless of its hardness. Even if a single tap water sample is analyzed and iron found not to be a problem, variations throughout the year are inevitable.

    Just like the decision to use less of a particular developer stock solution than its manufacturer's specified minimum quantity, this is a "confidence or crap shoot" situation. :smile:
     
  18. Ian Grant

    Ian Grant Subscriber

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    While not disagreeing remember that Kodak themselves don't actually specifical recommend using Distilled or Deionised water with Xtol in their Data-sheet. Traces of Iron will cause severe problems with fixers where the Iron and Thiosulphate form a fast acting bleach. I have had minute Iron particles in water way back in the 70's long before Xtol.

    Ian
     
  19. cliveh

    cliveh Subscriber

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    Every developer/stop/fix and many other photographic solutions I have ever made up, I have always used tap water. Never had a problem.
     
  20. Sal Santamaura

    Sal Santamaura Member

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    In my opinion, Kodak's lawyers have been vastly more competent than its executive management over the course of recent decades. :smile: Adding an "avoid iron" recommendation to the XTOL data sheet would have opened the company to liability for all the "dreaded XTOL failure" losses incurred by users of the product. Much easier to blame (and discontinue) the one liter packages. :D

    I dilute TF-4 fixer stock with distilled water too.

    The advantage to our alkaline and rather hard tap water here is that it is very effective at washing. A final Photo-Flo film rinse gets mixed with distilled.
     
  21. michael_r

    michael_r Subscriber

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    Ian, Sal, this comes up occasionally with respect to mixing XTOL. What I've never understood is - XTOL contains an Iron sequestering agent. So why would a small amount of Iron in the water be a serious problem? I can see how it would be a problem with home-mix ascorbate developers, but it shouldn't be an issue with XTOL.

    Also - Sal - regarding steam distilled being better than deionized for XTOL, actually I recall Gerald Koch saying it could potentially be the other way around if the steam distilling apparatus introduces Iron into the water.

    Just thought I'd throw that extra wrench into the XTOL/water quality debacle.
     
  22. Ian Grant

    Ian Grant Subscriber

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    All the reports of rapid failure were in the early years of Xtol production, Kodak must have made it more robust. Xtol keeps just as well as any other powder developer.

    Ian
     
  23. michael_r

    michael_r Subscriber

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    I've personally never had it fail on me. For a while I thought maybe there was something not quite right about how I was mixing it (using either deionized or distilled water) because my development times with TMax films were always longer than Kodak's indications. But no matter what I changed I always got the same results so I stopped worrying about it.
     
  24. Sal Santamaura

    Sal Santamaura Member

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    It's difficult to imagine that the cold side of a distillation process (condensing steam) might introduce more iron into resulting water than a deionizing plant would. In either case, iron levels have to be orders of magnitude lower than what comes out of some taps.

    I've never had an XTOL failure either. Steam distilled water is sold here in grocery stores at $3 for a 2-1/2 gallon container. Compared to the cost of everything else in photography, that's noise level. I see no reason not to keep using it for mixing/diluting XTOL and other powdered developers, diluting liquid developer/fixer concentrates and mixing Photo-Flo rinse solutions. Ultra-cheap insurance, especially where film is concerned.
     
  25. michael_r

    michael_r Subscriber

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    I do the same. I don't know if it is truly required, but whatever.
     
  26. DREW WILEY

    DREW WILEY Member

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    Most "deionized" water sold in this area is actually produced reverse osmosis. Try putting it in your car battery and see what happens. I'll stick
    with distilled, thank you.