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  1. #61
    michaelbsc's Avatar
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    Quote Originally Posted by Photo Engineer
    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
    Ok, so how many pounds, gallons, ml, or grams is reasonable to make in a batch? And how many square inches or square cm will that coat on average?

    And how do you coat? I'm familiar with costing flexible materials using a jet nozzle, buy that's beyond a common darkroom. Something like pouring a collodion?
    Michael Batchelor
    Industrial Informatics, Inc.
    www.industrialinformatics.com

    The camera catches light. The photographer catches life.

  2. #62
    Photo Engineer's Avatar
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    I have made from 5g or 100 ml to 150g or 3000 ml with no problem. These are slower speed. I am still working on the high speed emulsions which can only be made at about the 1/2 liter to 1 liter scale. I coat using my coating blade which has been discussed here over and over. I have 1 for paper, 1 for film and 1 for plates.

    PE

  3. #63
    Mustafa Umut Sarac's Avatar
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    Ron ,

    I found British and American documents from that time range as a list at internet. There are every kind of technology reports on engines to chemicals.
    If I order the copies of Agfa documents , would I be able to see the gelatin formulas or what is the source of Brovira Gelatin preperation technology ?
    Do you know them or Ian knows them ?

    Thank you ,

    Umut

  4. #64
    Mustafa Umut Sarac's Avatar
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    Ron , you posted 2 years ago ,

    Kodak was using the oxidized gelatin in the 40s while Agfa formulas still used 3 - 4 grades of active gelatin. This is not seen in Ian's formulas above, so I did some research...

    Brovira Extra Hard = Gelatine mittelreifend
    Brovira Hard = Gelatine mittelreifend
    Brovira Normal = Gelatine mittelreifend
    Brovira Special = Gelatine kraeftigreifend + Gelatine schwerreifend + Gelatine mittelreifend
    Brovira Weich = Gelatin kraeftigreifend + Gelatine schwerreifend

    A German - English dictionary will tell you that Reifend = Bloom, and you may wish to equate this with Bloom Index used today to classify viscosity and strength in gelatin, but these terms are not related.

    My Brovira formulas also include a spectral sensitizing dye (hier ist unbekannt - unknown at the plant) and an organic stabilzer added to the emulsion just prior to the coating operation.

  5. #65

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    Quote Originally Posted by Mustafa Umut Sarac View Post
    Ron , you posted 2 years ago ,

    Kodak was using the oxidized gelatin in the 40s while Agfa formulas still used 3 - 4 grades of active gelatin. This is not seen in Ian's formulas above, so I did some research...

    Brovira Extra Hard = Gelatine mittelreifend
    Brovira Hard = Gelatine mittelreifend
    Brovira Normal = Gelatine mittelreifend
    Brovira Special = Gelatine kraeftigreifend + Gelatine schwerreifend + Gelatine mittelreifend
    Brovira Weich = Gelatin kraeftigreifend + Gelatine schwerreifend

    A German - English dictionary will tell you that Reifend = Bloom, and you may wish to equate this with Bloom Index used today to classify viscosity and strength in gelatin, but these terms are not related.

    My Brovira formulas also include a spectral sensitizing dye (hier ist unbekannt - unknown at the plant) and an organic stabilzer added to the emulsion just prior to the coating operation.
    "Reifen" is (among other things) to ripen.

  6. #66
    Photo Engineer's Avatar
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    Reifen is indeed ripen which is used as a term with active gelatin which contains the natural sulfur containing amino acids which break down into allyl thiourea when heated with silver halide. This is why all old formulas MUST be converted to be used with modern gelatins or you just do not get the speed nor the contrast!

    PE

  7. #67
    AgX
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    "Reifen" is also used in conjunction with chemical sensitization when using in-active gelatin.

  8. #68

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    Quote Originally Posted by michaelbsc View Post
    Ok, so how many pounds, gallons, ml, or grams is reasonable to make in a batch? And how many square inches or square cm will that coat on average?

    And how do you coat? I'm familiar with costing flexible materials using a jet nozzle, buy that's beyond a common darkroom. Something like pouring a collodion?
    Micheal - you should sign up (and anyone else interested in learning more about this from a hands on viewpoint) for Denise Ross' classes at the Photographers Formulary next June (2011). Denise is an excellent teacher, and she makes the most beautiful handmade silver gelatin papers that I've ever seen. She's giving one class on papers, and one on plates.
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  9. #69

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    I don't think any one person, or even a small group of people will be able to match the level of technology that is in todays commercial color film products. But we as home emulsion makers can still make marvellous papers and B&W film/plate emulsions.

    We just can't compete with the amount of applied science that goes into these things. Which one of us is going to spend the hundreds of thousands of dollars for equipment and get the radiation licenses needed to make and operate a silver content meter to measure the amount of silver that is applied to our film as we run our home make emulsion coater?

    But we can still do great things, as individuals and through groups like this.
    Last edited by Kirk Keyes; 12-11-2010 at 12:38 PM. Click to view previous post history.
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!

  10. #70

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    Here's my contribution to the book club:
    "Photographic Emulsions" by E.J. Wall (1929)
    http://www.keyesphoto.com/KDKtech-E....Emulsions.html

    Again - it's old and needs to be read with a grain of salt (preferably a silver halide...).
    Kirk

    For up from the ashes, up from the ashes, grow the roses of success!



 

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