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  1. #51
    michaelbsc's Avatar
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    Quote Originally Posted by Photo Engineer
    Quote Originally Posted by michaelbsc View Post
    PE, are you serious that I can probably make pan 400ISO sheets at home given the techniques?

    And that I can make a color sheet film as well? At what speed? I assume this is a negative without orange mask?
    Yes, you could probably make an ISO 400 emulsion, but I think that you would find that making glass plates would be better than film.

    The color material would probably be a dye bleach material and would give slides. They would be very grainy and the film would be slow. A coupler based system would be harder to devise due to the need for custom chemistry. The couplers are just not available. A Kodachrome like product would be easier to make in some respects but harder to process.

    PE
    So what part of this was I expecting to be easy?

    MB
    Michael Batchelor
    Industrial Informatics, Inc.
    www.industrialinformatics.com

    The camera catches light. The photographer catches life.

  2. #52

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    Quote Originally Posted by Mustafa Umut Sarac View Post
    Can you copy and write [...]
    dwross,

    I too don't want to sidetrack this thread, but a word of warning: those two highlighted words spelled a bit differently, and page 4 of the scanned book, can get you in serious (and expensive) trouble.

  3. #53
    michaelbsc's Avatar
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    Dry plates I assume? Therefore transportable.
    Michael Batchelor
    Industrial Informatics, Inc.
    www.industrialinformatics.com

    The camera catches light. The photographer catches life.

  4. #54
    Photo Engineer's Avatar
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    Sometime about 1630, Samuel Pepys had a golf ball sized stone removed from his bladder by surgery. He was one of the few people who survived surgery in those days. If you had to have a stone removed, would you choose the surgical method used on him, or a modern method?



    I know, I know, this sounds stupid, but the fact remains that all works published on emulsion making that are dated before about 1940 have a similar relationship regarding both theory and practice to the example in my first paragraph. Even the FIAT and BIOS reports show emulsions that give some very nice products but are quite primitive. You will find that the old reports described in German, use the word "gekippt" which means that the ingredients were "tipped" or "dumped" into the reactor to make an emulsion. Well, one of the great advances that introduced constant and repeatable speeds was the use of pumps!

    Ok, then take this a step at a time. A better mixer gave better uniformity. Subsurface addition of ingredients removed the effects of foam, dual running of salt and silver gave better curve shape. Baker and Wall, and even Carroll knew nothing about these things in 1940! Can you do any or all of these in your darkroom? Of course you can! And that is part of my point here.

    PE

  5. #55
    michaelbsc's Avatar
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    Quote Originally Posted by Photo Engineer
    Sometime about 1630, Samuel Pepys had a golf ball sized stone removed from his bladder by surgery. He was one of the few people who survived surgery in those days. If you had to have a stone removed, would you choose the surgical method used on him, or a modern method?



    I know, I know, this sounds stupid, but the fact remains that all works published on emulsion making that are dated before about 1940 have a similar relationship regarding both theory and practice to the example in my first paragraph. Even the FIAT and BIOS reports show emulsions that give some very nice products but are quite primitive. You will find that the old reports described in German, use the word "gekippt" which means that the ingredients were "tipped" or "dumped" into the reactor to make an emulsion. Well, one of the great advances that introduced constant and repeatable speeds was the use of pumps!

    Ok, then take this a step at a time. A better mixer gave better uniformity. Subsurface addition of ingredients removed the effects of foam, dual running of salt and silver gave better curve shape. Baker and Wall, and even Carroll knew nothing about these things in 1940! Can you do any or all of these in your darkroom? Of course you can! And that is part of my point here.

    PE
    And I know for a fact that I'm not the only process control guy around here.
    Michael Batchelor
    Industrial Informatics, Inc.
    www.industrialinformatics.com

    The camera catches light. The photographer catches life.

  6. #56
    Photo Engineer's Avatar
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    Quote Originally Posted by michaelbsc View Post
    Dry plates I assume? Therefore transportable.
    Absolutely dry plates. Keeping at the present time is about 1 year for the uncoated emulsions and 1 year for the coated materials. I can do better, but there is just so much time to experiment and write.

    PE

  7. #57
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    Quote Originally Posted by michaelbsc View Post
    And I know for a fact that I'm not the only process control guy around here.
    I've found that you don't need full control with feedback loops. You just need a high impedence meter with the right electrodes and a syringe of salt to poke the vAg back into control. You see, salt rate needs to rise over an addition just to keep the salt in balance. The vAg is the measure of salt, and therefore you can just add salt from a syringe dropwise to keep the millivolts constant with your needs.

    No computer is needed.

    PE

  8. #58
    Mustafa Umut Sarac's Avatar
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    Ron ,

    I found your old post archives.

    Here is the Brovira Formulas Link :


  9. #59
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    Quote Originally Posted by Photo Engineer View Post
    I've found that you don't need full control with feedback loops. ...

    PE
    But, a geek like me cannot resist the beauty of a well-tuned analog PID controller
    - Ian

  10. #60
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    The post above on Brovira was not mine. Both Ian Grant and I posted Brovira variants in a thread here about a year or so ago.

    I would add that the formulas above do NOT explicity give the types of active gelatin used. Each grade of early Brovira and Kodabromide used a different type of gelatin tailored for the contrast grade. So the formulas above would either have to use old style gelatin blends or be revised for modern chemical sensitization methods. Also, Brovira did use Rhodium Chloride IIRC.

    PE



 

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