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  1. #21

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    Quote Originally Posted by fhovie
    How would you comapre DS1 to PC-TEA?
    I don't use PC-TEA in my practice. Gainer does not specify target pH for this developer. Sandy King measured the pH of PC-TEA, and triethanolamine is a wrong buffering agent for that pH. N-methyldiethanolamine or N,N'-dimethylethanolamine would be a better choice depending on the target pH intended by the formulator.

    DS-1 is a good developer similar to D-76d. Differences: (1) DS-1 produces fine grain image like D-76d, but without mushy grains. (2) DS-1 is less reliable when kept, in light of XTOL failures and lack of any active means of preventing the problems in DS-1. The latter can be fixed, so I could issue a new version of DS-1, but I decided not to pursue that direction because DS-10 produces superior image quality with almost all films except APX100. (and I think Martin Jangowski found a couple more films that don't work well in DS-10.)

    DS-1 can also be comapred to XTOL. Differences: (1) XTOL provides slightly finer grain. (2) XTOL provides slightly higher true speed.

    After all, DS-1 is a good general purpose developer if you don't mind mixing from scratch, but otherwise, there's not much worthy of comments. (Therefore I don't mention it very often.)

  2. #22

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    short answer-....Yes-


    L=(mr)2

    total system angular momentum

  3. #23

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    non sequitur
    Tom Hoskinson
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    Everything is analog - even digital :D

  4. #24
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    Quote Originally Posted by Ryuji
    I don't use PC-TEA in my practice. Gainer does not specify target pH for this developer. Sandy King measured the pH of PC-TEA, and triethanolamine is a wrong buffering agent for that pH. N-methyldiethanolamine or N,N'-dimethylethanolamine would be a better choice depending on the target pH intended by the formulator.
    My original intent in writing the article for Photo Techniques was to devise a split stock developer that might extend the storage life of ascorbic acid developers. Using TEA as solvent was an afterthought that works and provides a single solution developer with long storage life. There are many developers with little buffer capacity. If a target pH and large buffer capacity are considered necessary, the split stock idea with the developing agents in a glycol solution allows the use of any other solution as activator, etc. A plain 10% sulfite solution will give results similar to D-23, for example. Add a borax-boric acid or any other buffered alkali buffer if you want. These second solutions usually keep well and thus need not be incorporated in the glycol solution.

    Another idea is to use propylene glycol as the principal part of the solvent with just enough TEA to "neutralize" the ascorbic acid. I doubt that a pH meter's reading of that solution would accurately tell the pH after water is added, but I think that with 99% TEA a pretty good guess could be made as to how much to add to the first solution. The major impurity in TEA, according to Dow, is diethanolamine. I'm guessing that equimolar amounts of ascorbic acid and TEA would be close enough for government work.

    If I am right in assuming that the major cause of change in pH during development is products of the development reactions, and one-shot use of the working solution is the rule, and each person using a given developer will find time-temperature relationships to suit, then change of pH will be very nearly the same for each use and will not be an issue after the first determination of operating conditions.
    Gadget Gainer

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