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  1. #61
    MattKing's Avatar
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    Some who read over this and a few other related threads might sense a slight bit of tension therein , but that is not necessarily a bad thing.

    I expect that the big entities like Kodak, Agfa et al paid a lot of attention to the more empirical adventurers like Denise. And of course, Denise relies heavily on the efforts of Kodak and others when she experiments outside the more mainstream and current processes.

    It seems to me that PE and Denise have slightly different goals - their interests overlap a lot, but not in all ways.

    Together they might make a really good foundation for a university faculty - just enough different to ensure exploration and rigour, but sufficiently similar to ensure a productive learning environment.

    I make no comment, however, about how the department meetings might go .

    I wonder what the communications were like when that product we know as Kodachrome was being first worked on by those two musicians.
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

  2. #62
    MDR
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    Quote Originally Posted by MattKing View Post
    Some who read over this and a few other related threads might sense a slight bit of tension therein , but that is not necessarily a bad thing.

    I expect that the big entities like Kodak, Agfa et al paid a lot of attention to the more empirical adventurers like Denise. And of course, Denise relies heavily on the efforts of Kodak and others when she experiments outside the more mainstream and current processes.

    It seems to me that PE and Denise have slightly different goals - their interests overlap a lot, but not in all ways.

    Together they might make a really good foundation for a university faculty - just enough different to ensure exploration and rigour, but sufficiently similar to ensure a productive learning environment.

    I make no comment, however, about how the department meetings might go .

    I wonder what the communications were like when that product we know as Kodachrome was being first worked on by those two musicians.
    +1
    at least it wouldn't be boring and I would consider getting another uni degree with those two as profs :-)

  3. #63
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    That would be a ridiculous amount of fun . The "I'd do that for free" kind of fun.
    www.thelightfarm.com
    Dedicated to Handmade Silver Gelatin Paper, Film, and Dry Plates.

  4. #64
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    So would I.

    I think that the faculty meetings would be more fun than the classes!

    PE

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    This whole discussion has been an exciting learning experience. Where else do people battle about the best cations for halide salts? I never knew that potassium improved the quality of glass; and it never occurred to me that as the silver salts precipitated it would lead to a rise of ph in the solution. Of course horse urine is still being harvested for biological chemicals used in medicine and veterinary practice; I don't know if they collect phosphorus as a by-product. Certainly it is not an efficient method to secure the element. That happens to touch upon an area within my knowledge. But to second-guess PE about emulsions would be like telling Stradivarius how to make a violin. I hope he gets around to writing his book of color emulsions.

  6. #66
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    Well, I have to clarify one thing:

    NaBr + AgNO3 -> AgBr and NaNO3. Two mildly acidic reagents give one neutral reagent and one mildly acidic one, so the pH will move slightly up (less acid by a small amount).

    NH4Br + AgNO3 -> AgBr + NH4NO3 which represents a bit more acid as NH4 is a weak base compared to Na and so the pH will move slightly down. More acid by a slight amount.

    And gelatin acts as a buffer so the change depends on the amount and type of gelatin as well.

    Sincd NH4 ion is less effective as a complexing agent or Silver solvent as pH goes down (more acidic), its effect in the latter case will go down.

    PE

  7. #67

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    Hi to you all, I´ve been away on a long vacation and am more or less startled to find a discussion like this. I am not that experienced in emulsion making, but I know quite a lot professionally about handling conflict. So if need be.... I am enjoying emulsion making not overly burdened by loads of knowledge. I can find the Information I want on the site of the Lightfarm. And I am thankful for that. But if I want to know more or something else I`ll ask it here on the forum, as I have done before or anywhere else on the Internet. That is what the internet is for, not more or less. Problem is this kind of discussions make me shy away from this most informative place. After long years of crisis Intervention and conflict nanagement now in my old age I would like to be able to read the loads of information without extra hassle. Henk

  8. #68
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    Quote Originally Posted by Ian Grant View Post
    ...

    Another thing that's now conveniently forgotten was Kodak couldn't make consistent emulsions up until the the introduction of T grain films, a technology from Kodak Ltd in Harrow.

    ...

    Ian
    Are you claiming that Kodak emulsions up until the start of T-grain emulsions (80's) was inconsistent? If so, in what way "inconsistent"? variable results? unreliable?
    I know that some EK emulsions prior to that time were chosen for scientific/medical imaging for the very reason that they were so much more reliable than the other "big names".
    - Ian

  9. #69

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    The latest post by PE brings us back to the discussion of potassium vs. sodium, does the K+ cation form as strong a base as Na+?

  10. #70
    Ian Grant's Avatar
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    Quote Originally Posted by Hexavalent View Post
    Are you claiming that Kodak emulsions up until the start of T-grain emulsions (80's) was inconsistent? If so, in what way "inconsistent"? variable results? unreliable?
    I know that some EK emulsions prior to that time were chosen for scientific/medical imaging for the very reason that they were so much more reliable than the other "big names".
    That statement of mine does need qualifying slightly but it's not wrong

    First when I started photography seriously in the late 1960's Tri-X varied depending on the plant it was made in, data-sheets from Kodak for their developers would give different recommended for EI (then nominal ASA) and development times these would vary depending on whether the emulsion was made in the US, Canada or the UK. So in this case Kodak didn't have the controls they later had to produce the Tri-X e emulsion with exactly the same characteristics in different plants.

    At the same time Fujichrome Professional (E4) was very consistent batch to batch in terms of speed & colour balance while Kodak Ektachrome professional films came with a recommended EI (nominal ASA) and suggested correction filtration which varied batch to batch. So in the case of Ektachrome it wasn't totally consistent batch to batch.

    Ian

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