Ascorbic acid and TEA

Discussion in 'B&W: Film, Paper, Chemistry' started by shinn, Jun 22, 2005.

  1. shinn

    shinn Member

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    What would the shelf life of these be...?

    My ascorbic is an NF (99.9%) grade and has a expiration of 04' and the TEA which is also NF (99.9%-107%) expired in 02'. They are in seperate bottles:smile: and are still sealed.

    I do know that most "NF" or "USP" or "FCC" chemicals have expirations based on the usefulness in food or drugs. So I'm wondering if these are still OK for film?

    Also since the TEA comes in 85% technical as well as 99.9-107.4% would these react differently since it will be the accelerator in the formula I'm using.


    Happy Days
    Mark
     
  2. titrisol

    titrisol Member

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    TEA should be fine
    Ascorbic/ascorbate should still be useful. You;ll have to test for times for each film anyways.
     
  3. Gerald Koch

    Gerald Koch Member

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    Commercial grade TEA is not suitable for photographic use since it contains up to 15% MEA (monoethanolamine) and thus has a higher and unpredictable pH.

    Unless the ascorbic acid powder has a very dark color it's probably OK. When in doubt it's best to develop a test roll.

    I am unsure what is meant by "99.9-107.4%", you cannot have more than 100% purity.
     
  4. shinn

    shinn Member

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    Thanks guys...kinda what I thought.

    Gerald...It's an Assay...its what is in the catalog and many chemicals are listed as such including powders and I've never gotten a good answer as to why they list them this way.

    Happy Days
    Mark
     
  5. gainer

    gainer Subscriber

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    The Chemistry Store sells 99% TEA, according to the MSDS they supply with it. The contaminant in commercial grade TEA, according to Dow, is up to 15% of diethanolamine. At 4% solution, the difference in pH between 99% and Commercial is 10.1 to 10.3, as near as I can read from the chart.

    Isoascorbic acid, AKA erythorbic acid, is a little cheaper from the Chemistry Store and is just as good for photography, but no good as a vitamin. I've kept it a long time in powder form without deterioration.

    I think that sometimes expiration dates are stated so you will buy more. In medicinal use, you don't have much choice as a rule.
     
  6. srs5694

    srs5694 Member

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    Have you actually used this? If the guy who invented PC-TEA has no problems with TCS's TEA, then it's probably OK. :wink: FWIW, I used TCS's TEA to make one batch of a p-aminophenol/vitamin C/TEA developer. The developer works, but as it was my own playing around, I have no idea if it works the way it would work with, say, the much more expensive lab-grade chemistry, or if the results will be consistent if/when I mix another batch from another order of TEA.

    I assume this is the stuff that they sell under the "ascorbic acid" heading on their site. I'm only starting with mixing my own developers, but I've used it in three batches (including the one above), and they all work.
     
  7. Tom Hoskinson

    Tom Hoskinson Member

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    I bought a gallon of 99% TEA from The Chemistry Store and have mixed several different developer recipes with it over the last year. All of the developers work fine.

    Late in 2003 I bought a quart of TEA from Artcraft. Developers mixed with it also worked fine.
     
  8. gainer

    gainer Subscriber

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    Yes, I have used it. I don't see any need for the reagent grade. The variation in pH of even the commercial grade is not great enough to be of consequence IMHO.
    They cannot sell erythorbic acid as ascorbic acid. That would be misrepresentation, as ascorbic acid is the vitamin but erythorbic acid is not. Either one works in our developers. They are mirror images of each other. Erythorbic acid is used as a preservative and is not harmful, but it is no more a vitamin than citric acid.
     
  9. srs5694

    srs5694 Member

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    The reason for my comment is that I don't see anything listed as either erythorbic acid or isoascorbic acid on TCS's Web site. They do list ascorbic acid, though, in both "tech" and "food/USP" grade. The former is the cheapest I've seen for ascorbic acid.
     
  10. gainer

    gainer Subscriber

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    I have to apologize. I got my erythorbic acid from KIC Group. There is nothing wrong with using ascorbic acid. I have used the Technical grade, which may be a mixture of ascorbic and isoascorbic acids. It has been quite satisfactory.

    www.KICgroup.com specializes in large quantities, but can also furnish lab quantities.
     
  11. srs5694

    srs5694 Member

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    Ah, OK; that clears it up. No problem, and I appreciate the pointer. I've added them to my list of potential suppliers.