Distilled v. De-Ionised water for mixing developers

Discussion in 'Black and White' started by stephen_jones|4, Sep 12, 2002.

  1. In a previous thread, on Fx50, I mentioned that I used bottled water
    to mix my solutions. In one of the responses it was asked why I didn't
    use distilled water. The answer to this is that it is simply not
    available (as far as I can tell) in the UK. De-ionized water is
    invariably offered as an alternative. However, on page 190 of The
    Negative (A.Adams esq.) he counsels against the use of "softened"
    water saying that the removal of Calcium (as well as its exchange for
    other ions) is not ideal for photographic developers: "after
    softening, [the water] may have only 20ppm [of Ca++]. I understand
    that 180 to 200 ppm of calcium is ideal for most photographic processes."
    So, my questions are
    a. am I correct in thinking that de-ionized water has its calcium
    exchanged for sodium?
    b. is AA correct that it's needed?
    c. where can I get truly "distilled" water in the UK?
     
  2. I can't speak to the UK situation (so maybe I should shut up, right? grin), but I do know something about water purification.

    The softened water Adams refers to is what you get after you run water through a water softener: big cylindrical thing, looks like a water heater, with special salts inside. In the US at least, this is normally only used in homes that have hard well water (there are exceptions).

    Do you buy your "de-ionised" water at the local market? That's the way it's usually done in the US. Here, the stuff is sold as "purified water". This water is produced by reverse osmosis filtering, usually coupled with additional charcoal and possible resin filtering. It is actually better than consumer-grade distilled water for virtually all purposes, and the economics of its production have driven true distilled water from the market most places. If this is what you get, it'll be just fine for photo purposes.

    Marine aquarists have to deal with this issue (which is why I know about it). Ask at the local specialist aquarium shop (not a "pet store") and they should be able to direct you to a supply.
     
  3. Right before the part you quoted, Adams says: "Water of a pH of 7(neutral) is ideal. Distilled water is not exactly pH7, but is free of metallic ions and organic substances, and is adequate for mixing all developer solutions."

    In parts of the USA, the water is extremely hard (rich in minerals) and is softened by municipal water systems, or in some cases by water softeners in individual homes. I believe that this is what Adams was referring to when he warned about water softeners. I don’t really know how water labeled as “distilled” in the USA compares to ionized water in the UK. A bottle I purchased says that it was processed by distillation, micro-filtration and ozonation. I think most people recognize that such water is not 100% pure as would be used in a scientific experiment that called for pure H2O. In the USA, “distilled” water is available at most grocery or discount stores in plastic one-gallon jugs for $0.75 USD or less.
     
  4. Mark,
    but Calcium is not a metallic ion. If calcium is needed for the process, is removed by de-ionization but not by distillation, then I shall be in trouble. (unless somebody can recommend me a supplier of distilled in the UK)
     
  5. Any chemist (drugstore) in the UK will sell you distilled water. They give you funny looks but they charge so much that they don't ask too many questions. If it is not on display ask the pharmacist. When I was in the States I was amazed to see how cheap distilled water is in places like Duane Read. I am also interested to know if people advocate using distilled water to mix developer.
     
  6. Wal-mart sells distilled water for 58 cents per gallon in the U.S. Not exactly prohibitive. We will not be happy until all of the U.K. is Wal-Marted and Wal-watered.
     
  7. Ok, first let me clarify somethings about deionized water as there seem to be lots of inaccurate information in these answers.
    To obtain deionized water, the water is passed through two different beds composed of resins, not specialized salts! The cationic resin bed is also what is commonly used in water sofeteners in their sodium salt state. Normally for deionized water the cationic bed is in its Hydrogen state, meaning that as the cations are exchanged hydrogen is released, not sodium as it happens with a water sofetener. The water is then passed through an anion bed which removes the anions from the water and releases hydroxy groups, thus when the process is complete you get water. Of course this process is not 100% effective and there is some leakeage, usually this leakeage is small enough as to no make any difference in the prorcess. Let me put it this way if it is good enough for a nuclear plant, it should be good enough for your photo needs.
    OTOH the purest kind of water is distilled water, but the difference between distilled and de ionized water is so small that the additional expense to distill the water is not worth the benefits. At least in industrial and analytical settings. For photography you should not worry about getting distilled water, deionized is plenty pure for your requirements.
    Adams was correct in the sodium form cationic resin will trap calcium ions and release sodium ions, since sodium forms a "soft" scale with carbonate then you dont get that ugly hard scale on your sinkm bath etc. What is the effect effect of removing the calcium ion? well very simplu put you affect the ph of the water, making it more acidic and lowering the efectivness of the developer. Finally to your last question you are incorrect, de ionized water has the calcium ion exchanged for hydrogen ion, and subsequently the anionic species are exchanged for hydroxy ions, thus removing all salts from the water. This is why the process is so useful!
     
    • Most of the developers have substances like calgon (Sodium Hexametaphosphate) to sequester calcium.
    • to quote my 1939 Agfa Handbook "Distilled Water is Pure Luxury"... where it goes on to describe how to filter and decant water.
    • Distilled and de-ionized water are "different beasts". For photochemical applications you want, if at all, distilled water. Distilled water is available in different qualities (also sterile) from "Apoteke(n), Chemists, Farmacia, Pharmacies, etc."....
     
  8. Distilled and de-ionized water are "different beasts". For photochemical applications you want, if at all, distilled water
    There have been many advances since 1939.....one of them is in the use of zeolites and susequently the manufacturing of cross linked resins for ion exchange. The difference between destilled and de ionized water is merely in the degree of lekeage from the deionization beds. You do not need destilled water, deionized water is good enough, the difference in degree of purity between destilled water and deionized water is less than .01 micro mhos of conductivity, translated to total disolved solids, we are talking about 2 to 3 micrograms, harldy an amount to make a difference!
    Sterile distilled water only means that appropiate measures were taking to remove bacteria, which are not removed by the deionization process, and has nothing to do with degree of salts removal.
     
  9. Jorge is right on target. For developing I have been using deionized water for some time instead of distilled as I can get it for 25 cents per gallon at my saltwater fish store. I check it with a refractometer occasionally and it always shows a "0" specific gravity.

    It is my understanding that here in the U.S. when you buy grocery store containers of distilled water for steam irons etc. you are actually getting deionized water.
     
  10. Jorge, since you seem to know something about this... I thought the reason calcium removal was undesirable had to do with the exchange of residual thiosulfate from FB prints during the wash as well as pH of the developer. Is this true?

    I have very hard water with massive amounts of calcium and use a home water softner. I check my pH regularly and have never found it acidic - it's 7.3.

    Regards, Pete
     
  11. Pete, as to the thiosulfate exchange I am not sure. I have never heard of this and I am a water chemist so I am not knowledgeable in this phase of FB paper wash. If I speculate I would guess you are correct, since fix is sodium thiosulfate an excess of sodium ions in the water would tend to mantain the sodium thiosulfate from migrating out of the print. Is this correct? I dont know I am speculating but does sound like a reasonable thing.<p>
    As to the pH, remember that there are many other components in your water, flourine, chlorine etc, depending on the water composition these species can act as buffers and mantain your pH level. Without looking at an analysis of your water I am unable to tell you why this is, but I can tell you that one of the ways we measure bed capacity in a cation exchange vessel is by measuring the pH, initially it is very low, and as the bed loses capacity the pH rises. <p>
    OTOH my obvious question to you, is since you are using softened water, do you see any detrimental effects in your processing? I would guess you dont. If anything I would guess that if you process without the softener you would get a lot of calcium carbonate scale on your film/prints. Not a good thing unless you like spotting!<p>
    Lastly and more likely is the fact that home water softeners systems are not as efficient as industrial reactors, so if you have used your resin for more than 5 years, which is the average life span of the resin then I would speculate you are leaking some calcium significant enough to keep your processing accurate but is removing enough to prevent scaling on your home appliances.
     
  12. Ok, BTW I have to admit that as much faith I have on deionized water, after all I make my living with it, I use destilled water for my photo needs. The way I solved this problem was to buy a water destiller from one of those "health" places on the internet. The one I purchased makes about 4 gallons a day and for developing film is great. <p>
    Having said this, I also used the "distilled water" bought at the supermarket (which is nothing but deinozed water, I know because I checked the conductivity of the water which showed it was obviously deionized) and I can tell you my negs look exactly the same with either water. If you do not wish you buy a distiller, or is more convenient for you to use de ionized water, do not worry you will not notice a difference!
     
  13. Having read all the previous posts, now I wonder what I've done wrong for the last 25 years mixing developer with tap water. Only this year did I change to distilled water for mixing developers, and yet I have never noticed a problem. Doing it right is stll the best way though, I won't go back.
     
  14. No one said that everyone needs distilled water. It depends on the developer and the quality of your tap water. Some people report that their tap water varies in chemical composition at various times during the year. And it helps not having to worry about the water if you relocate or develop away from home. At less than $0.75 per gallon, it seems like cheap insurance to maintain consistency. Consistency should be a prime objective in film developing.

    The point that started this thread is that if one wants to purchase bottled water for developing, one should use distilled (or ionized water as it may be called in the UK) as opposed to bottled drinking water. Bottled drinking water is usually high in minerals, which is one reason it tastes better than some tap water or even distilled water.
     
  15. My well water is very hard, with both calcium and magnesium. It is good drinking water, much like what some people pay good money for. I have read that heart disease is less common where the water is hard. I can and do use it straight drom the well in developers that have borate alkali. With carbonate, I get a cloudy mix unless I use edta or Calgon. I use either distilled water or water from my dehumidifier for film developing, and usually use the EDTA or Calgonite for print developing, mostly so I will be able to see the print through the developer.
    I use the distilled water whenever I am doing experiments to report to others.
    Pat Gainer
     
  16. MTC  Photography

    MTC Photography Moderator

    Some drug stores in Toronto sell de-ionized water; Loblaw supermarkets sell "steamed distilled water"--- the one I choose
    for mixing my film developer and fixer. Because developing Minox 8x11mm need much more care than developing 35mm film, Minox negatives
    are routinely enlarged to 15x or 25x, any residue will show up on
    print.
     

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