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  1. #21
    Photo Engineer's Avatar
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    What did you actually measure in the developer Mark?

    Also, note what it says above about water uptake. DEA and TEA are very hygroscopic.

    You should also note that Density is not additive. You cannot be assured that you can take 1 gram of each of 2 compounds and get the density half way between when you mix them. It does often work though. But, you have to use mole ratios not weights IIRC.

    PE

  2. #22

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    Quote Originally Posted by Photo Engineer View Post
    What did you actually measure in the developer Mark?
    Also, note what it says above about water uptake. DEA and TEA are very hygroscopic.
    You should also note that Density is not additive. You cannot be assured that you can take 1 gram of each of 2 compounds and get the density half way between when you mix them. It does often work though. But, you have to use mole ratios not weights IIRC.
    PE
    I mixed Instant Mytol before I had the pH-meter, so I measured the pH of the working solution with pH-strips. Close to 9. And results were much denser than XTOL, consistent with a too-high pH. I mixed the stuff when I got the TEA from PhotoFormulary, so water hopefully hadn't gotten in at that point.

    But I'm mostly wondering why my 4% solution of TEA has pH=10.8 when 10.1 was expected. I figure there's too much DEA in it.

    Mark Overton

  3. #23
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    Ron, was Jay's idea of heating the tea in the oven sufficient to get rid of the water? Could we make this source usable?

  4. #24
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    Heating TEA in a microwave or regular oven is NOT a good idea. It is very hard to drive the water out. But, having water present is not bad per se. The problem can come from the DEA which is different in solvent effects and pH. Once you standardize on that, there is no big prblem. So, that is why I use TEA with 15% DEA in it. I have standardized on it and it works. Not everyone should or could do that, but as I say, it works for me!

    PE

  5. #25

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    Just to add to what PE said; you should never heat chemicals in a microwave oven or regular oven that is also used for food. Heating TEa or glycols above 100 C can cause them to "bump" as steam is released. This can cause spatters. TEa is flammable and heating it can cause a fire if there is an open flame.

    Standardizing on a mix of TEa and DEA is OK but makes your formula non-portable to others. Technical grade TEA contains a variable amount of DEA and even some MEA and so its properties are variable from sample to sample. TEa of 99% purity is readily available but always read the MSDS before purchase.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  6. #26
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    Quote Originally Posted by Gerald C Koch View Post
    Just to add to what PE said; you should never heat chemicals in a microwave oven or regular oven that is also used for food.
    This is exactly my problem with all these TEA based recipes. While it's convenient to have a solvent which prevents your developer from oxidation, works as a silver solvent and has high pH in aqueous solution all at once, the recipes recommend preparation of stock solution at temperatures beyond 100°C, which means people with no access to a chem laboratory (i.e. most home brewers) will inevitably do this in their kitchen at some point in time.

    I understand the fascination a simple and long lasting stock developer solution has on many home brewers here, but I wish these recipes didn't involve heating of toxic and possibly carcinogenic substances.
    Trying to be the best of whatever I am, even if what I am is no good.

  7. #27
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    Muahaha! I have my own "secret" method! It is totally safe and everything dissolves.

    Actually, there is a safe method that uses nothing higher than 40 deg C (100 F) and a water bath. I may describe it someday.

    PE

  8. #28

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    I have mentioned on several threads that Dimezone, Phenidone, and ascorbic acid will dissolve in glycols or TEA at room temperature if one is patient. What I recommended was putting the developing agents and glycol in a bottle and gently shaking it periodically until the solids dissolve. The bottle can be gently warmed, say to 50 C, during this process to speed solution. If one uses a mixture of glycol and TEA then the TEA should be added after the solids dissolve and the solution has cooled. I have used a 1:1 mixture of glycol and TEA in the final concentrate.
    Last edited by Gerald C Koch; 01-31-2012 at 01:09 PM. Click to view previous post history.
    A rock pile ceases to be a rock pile the moment a single man contemplates it, bearing within him the image of a cathedral.

    ~Antoine de Saint-Exupery

  9. #29
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    See how simple it is? Jerry got one method right off. There are several others that are almost identical!

    Oh, I like mine stirred, not shaken!

    PE

  10. #30
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    I take your point that one could mix PC-TEA or the like at elevated room temperature by adding a little bit of patience to the mixing procedure - but that is not what most instructions posted online state. I have argued in another thread that home brewing is a field one can easily enter - it does neither require a PhD in chemistry nor 5 digit amount of money to get started. It takes only one silly mistake to be disabled for life, though. Given this I suggest we consider this thread again when we post recipes, especially recipes aimed at casual users like those which create long lasting stock solutions.

    Sorry for my OT rant.
    Trying to be the best of whatever I am, even if what I am is no good.

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