why TEA in DS-14

Discussion in 'B&W: Film, Paper, Chemistry' started by MSchuler, Feb 19, 2008.

  1. MSchuler

    MSchuler Subscriber

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    I'm considering trying DS-14, as I have a Nova processor and like the idea of a developer that can be replenished. However, I'm wondering what the purpose of TEA in this formula is. Is it doing something that other more regular developer components can't?
     
  2. Snapshot

    Snapshot Member

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    It's my understanding that it is used as a chelating agent, which can extend the shelf life of the stock solution. In addition, TEA can be used as a buffering agent.
     
  3. Tom Hoskinson

    Tom Hoskinson Member

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    TEA is not a chelating agent, it is a viscous liquid alkali that can be used as a buffering agent. The (iron) chelating reagent in DS-14 is Salycilic Acid.
     
  4. Snapshot

    Snapshot Member

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    To quote from the Silvergrain website...

    At that time, my preferred chelating agent was triethanolamine and diethanolamine. These are more effective than those above, and they can be used as a buffering agent, but their efficacy in stabilizing developers was unpredictable depending on the formula, until much later time.

    Here is where the quote can be found....

    http://wiki.silvergrain.org/wiki/Ascorbate_Developers

    It seems that Ryuji thought it had useful chelating properties.
     
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  5. Lowell Huff

    Lowell Huff Inactive

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    Triethanolamine is an accelerator
     
  6. Snapshot

    Snapshot Member

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    At 5ml per litre of DS-14 solution, TEA isn't much of an accelerator.
     
  7. Tom Hoskinson

    Tom Hoskinson Member

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    Suzuki on Salicylate:

    http://wiki.silvergrain.org/wiki/Ascorbate_Developers
    “In the summer of 2003, I found a relatively recent research that salicylic acid is an effective iron chelator, and this form of iron is inactive as the oxidation catalyst. I compounded a few ascorbate developers incorporating salicylic acid, and observed how long the solutions lasted. The result was very promising.”


    TEA 99% (a tertiary amine used to react with acidic compounds to form salts) – a weak base that can be used as a pH adjustor.

    http://www.sciencelab.com/xMSDS-Triethanolamine-9927306

    TEA Physical state and appearance: Liquid. (Clear viscous liquid.)
    Odor: Ammoniacal. (Slight.)
    Taste: Not available.
    Molecular Weight: 149.19 g/mole
    Color: Colorless to light yellow.
    pH (1% soln/water): 10 [Basic.]


    Haist on Triethanolamine (pages 248-250 of Modern Photographic Processing, Volume 1).

    “Triethanolamine was suggested in 1937 by Maurice Ney for fine-grain development. Triethanolamine is weakly alkaline, does not attack gelatin or film base and is odorless and non-irritating (unlike acetone). The developer containing it was said not to lose its alkalinity…”
     
  8. Snapshot

    Snapshot Member

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    Throw all the data sheets and Haist quotes you want as I'm not arguing that TEA isn't used as an accelerator (nor am I'm arguing salicylic acid isn't being used as a chelator). However, I am under the belief that Ryuji included TEA in DS-14 to act as a chelating agent. Salicylic acid is included as an iron chelating agent but it doesn't preclude other agents being added, unless there is some law that I am unaware of that precludes such.

    The question that was posed is why TEA included in DS-14, a Ryuji formulation. I'm very doubtful it was intended an alkali accelerator as 5ml not enough to provide this action. That is why there is 30 grams of carbonate. It very possible TEA has been included as a buffering agent. However, with DS-14 having a pH 10.4 I'm a little doubful of this. Regardless, Ryuji has clearly stated that he used TEA as a chelating agent. Anyway, unless someone knows his mind this isn't going to get settled.
     
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  9. Ian Grant

    Ian Grant Subscriber

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    Take what Ruyuji writes with pinch of salt. There are many errors on his Silvergrain website, and even when others point him to the correct original (primary) sources he still perpetuates his mistakes.

    Ian
     
  10. Snapshot

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    Fair enough. I'm not trying to redefine what the role of TEA plays in photographic chemistry, just trying to answer the OP question. Heck, I use TEA as an accelerator in some developer formulas.
     
  11. Tom Hoskinson

    Tom Hoskinson Member

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    Why don't you PM Ryuji and ask him?
     
  12. Snapshot

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    D'oh, why didn't I think of that?
     
  13. Ryuji

    Ryuji Member

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    No need. Somehow the wind pushed me this way.

    I know what's in my mind, and I tell you that the main purpose of TEA in DS-14 is iron and copper chelator. It is true that I use TEA for some other purposes (e.g., alkaline buffer, radical scavenger, solvent and what not) in other developers, but as you correctly pointed out before, these roles are largely irrelevant in DS-14, with possible exception of radical scavenger. Salicylic acid is also intended as an iron chelator (and again, also a radical scavenger), but the effect of both used together is superior. If only one is used, I would have to use a lot more. Since these agents do not directly contribute to developing reaction, these agents are eventually carried over to stop or somehow discarded. So, it is my best intention to minimize the chemical waste and save some pennies. The quantities of TEA and salicylic acid are rather small, but you'll see improved keeping properties. I keep my DS-14 and Tektol developers in my slot processors for months. One key factor I found to influence the shelf life (without complete airtight closure) is ambient temperature. DS-14 gets oxidized faster in open trays in a hot darkroom (in a closed, full glass or PET bottles, this is irrelevant).

    I've tried many chelators and radical scavengers, and these are two of my early hits. Now I know some better ones but they've become my favorite chemical tricks and I still use them a lot when they can do the job.

    I might also add that, in photographic chemistry (both emulsion making and processing chemicals), it is not uncommon to see one agent used in different places for distinct functions. It is also not uncommon to see one agent playing multiple roles in one solution. Sulfite in developer is a prime example.
     
  14. Snapshot

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    Thanks for clarifying, Ryuji.
     
  15. gainer

    gainer Subscriber

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    Perhaps the TEA along with the salycilic acid should be considered as a more-or-less neutral chelating agent in the phenidone-ascorbic acid-carbonate developer. I would not expect Ryuji to take the "let's put a little XYZ in there and see what happens" attitude. Having a working PAC combination, a theory about the effect of that particular valence of iron on the ascorbate, and a theory about the effect of a salicylate on the iron, I would expect him to use a neutral solution of salicylate of some sort to test the theory and determine the required amount if it works. OTOH, what was it someone once said about the difficulty Occidentals have understanding the Oriental mind?

    I have noticed that some of us try to treat the effect of each ingredient separately without considering various possible combinations. If we added ammonium salicylate, we might look at it from a different perspective than adding ammonium hydroxide and salicylic acid separately. Try thinking of the TEA as an organic analog of ammonia. Perhaps methyl salicylate would work as a replacement for both TEA and salicylic acid. If so, the developer might have an enticing odor of Wintergreen.
     
  16. Ryuji

    Ryuji Member

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    I do try a lot of things for screening. But I then have an array of large vials with one base developer and one additive in a vial... with one blank control. Then I adjust the pH of each vial with NaOH or sulfuric acid. ... and test them all. The thing is that you kinda have to select the range of additives wisely, because there are so many compounds and my array can hold max of only 24 at a time. Salicylic acid and triethanolamine were not randomly selected for inclusion, tho.

    Ammonium salts in developers are not recommended. It'll smell like ammonia in an alkaline solution. It has a very strong solvent effect and can deteriorate granularity and also can cause dichroic fog with some emulsions. It is definitely not recommended in print developers.
     
  17. Ryuji

    Ryuji Member

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    Ammonium salts at alkaline pH is a strong silver halide solvent, and it was once used popularly in making of high speed iodobromide emulsions (this is called a ripener, to enlarge grain sizes to gain speed). It is rather convenient because the solvent effect can be turned on or off by adjusting the pH. However, at the higher pH where the effect is used, the emulsion also gets different effects (which can be useful in some cases, but in others it leads to elevated fog and not very desirable) and also the vapor of ammonia is objectionable, so it got replaced with a number of alternatives in modern practice. (I personally do not use ammonia in my emulsion making but can make ISO 1000 emulsions.)

    Triethanolamine has only a weak solvent effect, on the other hand. It is more easier agent to use in developers, as the risk of dichroic fog is pretty low.

    (Although modern films have the top coating layer incorporating compounds that prevent dichroic fog from most reasonable developers...)
     
  18. dancqu

    dancqu Member

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    So Skip the TEA and Salicylic Acid?

    Use distilled water for same results? Dan
     
  19. Ryuji

    Ryuji Member

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    No. I've said many times that the impurities come with other chemical stocks, not just water.

    How many reports of sudden XTOL death using distilled water?

    Got the point?
     
  20. Paul Verizzo

    Paul Verizzo Member

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    Radical Scavengers?

    Is this something the police wished they had in the sixties? Especially at the Chicago Democratic convention? :rolleyes:

    Or, just what radicals are in developers?

    Thanks,
     
  21. Ryuji

    Ryuji Member

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    Paul, the real answer is long, but will give you a short one:

    http://en.wikipedia.org/wiki/Radical_(chemistry)

    I don't know if this is what you wanted to hear, but free radicals occur in many places in photography. One place is development reaction, and the lifetime and fate of radicals of the electron transfer agent has a lot to do with the superadditivity of developing agents. Radical reactions are also important in aerial oxidation of developers.