calcium ascorbate

Discussion in 'B&W: Film, Paper, Chemistry' started by jim appleyard, May 13, 2005.

  1. jim appleyard

    jim appleyard Member

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    Several months ago I bought a bottle of vitamin C at the health-food store to use for developing (E-76, Rodinal, etc.) and haven't opened the bottle yet, (but too late to return it) but I just now noticed on the front it says, "non acidic". Well, of course that made me wonder what is in the bottle. It turns out that it is not sodium ascorbate, but calcium ascorbate.

    I *think* that it's the same type that I've used successfully with E-76 before, but it may explain why my Rodinal w/vitamin C attempts were less than stellar.

    Can calcium ascorbate be subbed for sodium ascorbate? And if so, can it be subbed equally?

    Obviously this changes the ph of any soup to be made, but how much and how to compensate?

    Does it change dev times any?

    Anything else I might need to know???

    All is not lost, however; I can add it to beer and make a health drink out of it!
     
  2. john_s

    john_s Subscriber

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    As a general rule, calcium is something that you don't want in photographic solutions, since its presence can lead to deposits on the film.
     
  3. argentic

    argentic Member

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    I don't think calcium ascorbate is what you want. Search the apug threads about "Vit C", "Ascorbate" or "Gainer".
     
  4. jim appleyard

    jim appleyard Member

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    John, where is the lead coming from, my indoor plumbing?



     
  5. Maine-iac

    Maine-iac Member

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    Jim, as near as I can tell from the little Google research I've done, both sodium and calcium ascorbates are buffered forms of ascorbic acid, mostly used for those people who need Vitamin C supplements, but don't want the acidity.

    They are not strictly interchangeable in a formula with asorbic acid. I'm sure Pat Gainer knows the correct proportions to use for the ascorbate form. But obviously, if it's not acidic, it will affect the pH of the formula. I've never used the ascorbate form, preferring the straight ascorbic acid, but many on this forum have.

    The calcium and sodium varieties appear to be pretty much interchangeable for dietary purposes, but I'm not sure about the calcium variety in a developing formula. I'd tend to agree that it might lead to some deposits on the film, but that's only a guess.

    Larry
     
  6. Ole

    Ole Moderator Staff Member Moderator

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    The problem isn't the calcium ascorbate, but how the calcium can react with the other chemicals in the soup. There are many calcium compounds with low solubility - like calcium sulfate (gypsum) and calcium carbonate (lime). I don't know the solubility of calcium sulfite and Ca-borate offhand, but I suspect they are good candidates for low sulubility too...
     
  7. glbeas

    glbeas Member

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    Would it be possible to mix the calcium ascorbate solution with sodium sulfate and precipitate out all the calcium first? A guess to the proper ratios?
     
  8. Gerald Koch

    Gerald Koch Member

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    Calcium sulfite is even less soluble in water than calcium sulfate. The two solubility products are 6.8 x 10-8 and 9.1 x 10-6 respectively. Save the calcium sulfite for its intended use and buy some sodium ascorbate.
     
  9. Gerald Koch

    Gerald Koch Member

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    Sorry meant to say "Save the calcium ascorbate ...".
     
  10. Ole

    Ole Moderator Staff Member Moderator

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    Great! So you can precipitate out the calcium with sodium sulfite, ending up with sodium ascorbate :smile:
     
  11. Paul Sorensen

    Paul Sorensen Member

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    I agree that Calcium Ascorbate is a great supplement. No "sour stomach" after taking vitamin C. No opinion on its use in a developer, but it is the only kind if vitamin C I take.
     
  12. Donald Qualls

    Donald Qualls Member

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    It would probably be both simpler/cheaper and more reliable to use sodium carbonate to replace the calcium in the ascrobate you have. Mixed in solution with a slight excess of the carbonate, you'd get a slightly alkaline pH, which would prevent the carbonate from staying dissolved, and the precipitate would then filter out readily with a coffee filter or similar. The resulting sodium ascorbate solution would then be completely usable in developing. It would probably be desirable, both from a chemical standpoint and to avoid dilution, to use the minimum amount of water to perform the precipitation, and of course you'll want to weigh both components and do a little chemistry work to verify what strength the resulting solution comes to, so you can measure it accurately.

    Sodium carbonate is really, really, cheap, BTW -- you can get it in the monohydrate form in a box marked "Arm & Hammer Super Washing Soda" at most larger grocery stores in the United States (in the laundry section, right next to the 20 Mule Team Borax); the box holds something like three pounds, and will cost you less than three dollars.
     
  13. Maine-iac

    Maine-iac Member

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    And it smells nice, too. Nice fresh laundry smell.
    Larry
     
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  15. jim appleyard

    jim appleyard Member

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    Thought I'd bring you folks up-to-date on my calcium ascorbate use; I haven't tried it as a film dev., but it works well in print dev. E-72 from "The Darkroom Cookbook".
     
  16. gainer

    gainer Subscriber

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    No, because if you try to dissolve calcium ascorbate in water you will have nothing but precipitate to begin with. Don't bother to try anything called "Ester C". The body uses these as fat-soluble vitamin.

    It will cost you less in time and money if you find ascorbic acid. Sodium ascorbate is useful in some applications, but it is not very soluble in glycol or TEA. It is the best stuff to get for perverting Rodinal or making an Xtol expedient, but you can also easily make it with ascorbic acid and baking soda. It depends on how varied your uses might be.

    Even soluble calcium or magnesium compounds should not be used in solutions along with carbonates. Magnesium carbonate makes a very white cake, but unless that is what you are trying to make, even hard water should be avoided or doctored with a sequestering agent like EDTA.
     
  17. gainer

    gainer Subscriber

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    Just to be sure, I tried dissolving 3 calcium ascorbate tablets, one each in 1)tap water from my well, 2)potassium carbonate solution and 3)HCl (muriatic acid). The water softened the tablet but did not dissolve it, as expected. Strangely, the potash solution, a very strong one as used in Pyrocat HD, did not even soften the tablet after standing all night. HCl made a slurry of most of the tablet. I was expecting calcium chloride and ascorbic acid. Of course, the tablets have other stuff as filler, etc. Adding the carbonate to this slurry made lots of foam, which may have contained calcium carbonate and potassium ascorbate along with the CO2 from excess acid.

    The E-72 formula must be in a later edition of The Darkroom Cookbook than the one I have. Does it simply substitute ascorbate for hydroquinone?
     
  18. titrisol

    titrisol Member

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    Ca-ascorbate should be very soluble in water though....
    Here it doesn;t give data but I guess it should be more than 100 g/l
    maybe the stuff you got has some non-soluble filler.
     
  19. jim appleyard

    jim appleyard Member

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    Sort of. It subs ascorbic acid for the Q. Here's the recipe:
    Water 750ml
    Phenidone 0.3 g
    Sod. Sulfite 45 g
    Ascorbic acid 19 g
    Sod. Carb. mono 90 g
    Pot. Bro. 1.9 g
    water to make 1 liter

    This is from the 2nd edition of the Cookbook.

    I guess all that carbonate takes care of the acid problem.

    I've been using up my bottle of Calcium Ascorbate (sold as Vit. C in the local health-food store). I didn't want to use it in a formula for film, but it seems to work ok for paper.
     
  20. gainer

    gainer Subscriber

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    You could save money by leaving out the sulfite. It doesn't protect ascorbic acid from aerial oxidation. Ascorbic acid protects the phenidone.

    I don't see how you can dissolve calcium ascorbate in a carbonate solution without precipitating a bunch of calcium carbonate. In order to get the equivqlent of 19 grams of ascorbic acid, you would need a lot more than 19 grams of calcium ascorbate. I haven't worked out the ratio, but it's simply proportional to the molecular weights, allowing for the fact that each molecule of calcium ascorbate has two molecules of ascorbic acid - 2 H. On second thought, maybe the ratio is not so great.
     
  21. jim appleyard

    jim appleyard Member

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    Glad to know I can save a $.

    Oh, believe me, I get precipitate and perhaps this isn't the ideal dev mixture in the world; I'm just using up the cal ascorbate.

    I thought of adding it to beer, to make a health drink, but why ruin a perfectly good good bottle of cal ascorbate by adding it to Old Milwaukee Light? :wink:
     
  22. Gerald Koch

    Gerald Koch Member

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    Ascorbic acid and sodium ascorbate cannot be used interchangeably and the easiest thing is to keep both on hand.

    The cheapest source of sodium ascorbate (in the form of sodium erythorbate) that I have found is from Sutton Bay Trading Company at $6.33 a pound. http://www.suttonsbayspices.com/ Go to the sausage making section.
     
  23. gainer

    gainer Subscriber

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    I was having a senior moment. I hate to think it's happaning. I know I wasn't going off half crocked. I haven't been drunk since my fraternity days. A good many of you were just a twinkle in your father's eye at the time of that party.

    I did figure out why my Ester C tablets wouldn't dissolve in anything but HCl. The one I tried to dissolve in potash solution is still intact. I'm pretty sure the pills were coated with something to keep them from dissolving on the way down to the stomach, where they would come into quite strong HCl. Perhaps my tap water is acidic enough to soften them.

    Anyway, I couldn't find any pure calcium carbonate locally. It all had bioflavenoids and acerola. It still is not a good idea to use calcium ascorbate if you can get ascorbic or erythorbic acid. It is so easy to make sodium or calcium ascorbate from the acid.
     
  24. Donald Qualls

    Donald Qualls Member

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    Pat, try a stick of chalk from the nearest school house. Even the little stubs that are too small to hold. For that matter, if you're in the Appalachians, as I recall you are, go out in the hills and pick up almost any rock you see, it's probably limestone, which is calcium carbonate.

    Oh. Er, they *do* still use chalk in schools, right?
     
  25. gainer

    gainer Subscriber

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    Yes, I live in North Central West Virginia in the Allegheny mountians which were formed by water from plains raised up in the formation of the Blue Ridge mountains.

    I don't think that black stuff we have in our back yard is limestone. It burns. The red stuff we have on the other side is red clay, which has a lot of iron. We also have soapstone, which is gray clay. Sometimes, if you dig deep enough, you get a well out of which comes some greenish liquid that also burns. The gas coming out of those holes stinks and also burns. It's pretty darn hard for a farmer to make a living here. Even the cattle have shorter legs on one side from grazing on the sides of mountains. We have clockwise cows and counterclockwise cows. Nothing in the world is more frustrated than a clockwise bull with a herd of counterclockwise cows.

    It's a pretty good chance that the coating of the tablets I tried to dissolve would write on a blackboard. It surely will not dissolve in a carbonate solution. Chalk would, of course, dissolve in HCl. I was wrong about the solubility of calcium ascorbate, but don't bother to try using it in the form of tablets.

    The slate boards that would accept chalk markings are history. They are green boards now.
     
  26. Donald Qualls

    Donald Qualls Member

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    Well, Pat, I did say *rock*. One might argue that coal is a rock, but I don't consider it such. None of that other stuff you mentioned is rock, but there *is* limestone rock in the West Virginia hills (there must be, they have caves there). If you're not in the area that has caves (and you probably aren't, limestone and coal don't go together AFAIK), then you probably don't have anything I'd think of as rock until you dig down through the coal -- and then it's probably slate, mudstone, or possibly dolomite.

    Even the green boards in schools take marks from stuff marketed as chalk, but as I recall, it's got little actual chalk content these days -- zinc oxide in some friable binder so it makes a nice bright white mark and can be used to mark on "blackboard paint" which, as you say, is often green.

    Oh, never mind. :tongue: