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  1. #11
    Photo Engineer's Avatar
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    Ian, you are correct except for the words "self cleaning". After a bad mess due to a poor coating formula, I worked until midnight with the coating crew and a large putty knife cleaning up the machine!

    PE

  2. #12
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    Ron,

    As is often the case, you have raised more questions than you have answered, but I won’t nag .

    I did learn that NaBr is more than a rarely used novelty. I did not know that. I’ve never seen a NaBr emulsion recipe. Obviously, I’m not implying that I am privy to all of the recipes that have ever been made. I’d rather contemplate the number of stars in the sky than try to guess how many variations on AgX have been run through the kettles!

    I do have one observation. I believe you would contribute more to the knowledge that I know you want to share if you could be a little more careful with the shorthand and jargon. Back in the thread, ‘Ammonia or Ammonium salts in emulsion making’, you stated, “And, virtually none of the hundreds of emulsion that I worked with at Kodak used Ammonia in any form.” But, you have posted your Single Run Ammonia Digest recipe on APUG, and today, you are describing the use of ammonium sulfate. I find those juxtapositions confusing and I have a fairly good chemistry background. Just a thought, submitted with the greatest respect.
    www.thelightfarm.com
    Dedicated to Handmade Silver Gelatin Paper, Film, and Dry Plates.

  3. #13
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    Denise, I have examined literally thousands of emulsions over my 15 years in Emulsion Research. Of those, very few used any form of Ammonia, and few used Digestion. You see, if you want a cube (Essential component of Ektar 100) you cannot digest as it rounds the corners and you no longer have cubes.

    If you want a thin t-grain, use of an Ammonia digestion will change thickness or shape. In other words, very often Ammonia keeps you from getting from here to there. Ripening works (no solvent) but digestion is an impediment.

    So, out of these thousands of emulsions, very few used Ammonia in any form. Then too, we had more recent methods of doing a digestion, which is far far beyond the scope of the work we might discuss here.

    And so, as an easy way to make a fast, single run emulsion that is fairly monodispersed, I used the Ammonia digest that is in my book and posted (in part) here on APUG. It is subject to fog but has reached speeds of ISO 40 - 80, and I have made an ortho version of it.

    We do not plan to do that at GEH, as the Ammonia fumes, even in trace amounts, can be detrimental to the rare objects preserved there. We are approaching the speed angle from a different POV.

    As you will find, Ammonia digests of any sort without massive ventilation is quite daunting. However, my current and past comments are not mutually exclusive but merely reflect a broad range of possible emulsion types.

    We had over 200 emulsion makers in our division (and WW). They averaged 1 emulsion per week. This is about 1000 / year and over 15 years is over 10,000. They all did not go into production, but just about every one passed through my hands or the hands of a member of my group at one time or another. I cannot generalize these easily, but can say that the use of any form of Ammonia was a rarity.

    PE

  4. #14
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    Ah... so that was a method of "employee discipline" at EK?

    Quote Originally Posted by Photo Engineer View Post
    Ian, you are correct except for the words "self cleaning". After a bad mess due to a poor coating formula, I worked until midnight with the coating crew and a large putty knife cleaning up the machine!

    PE
    - Ian

  5. #15

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    Ian, get a copy of Bob Shanebrook's book. A fascinating look at the complexity of the coating machinery/process.

  6. #16
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    I've got the book, but it doesn't have a picture of Ron scraping down a coating machine

    Quote Originally Posted by Michael R 1974 View Post
    Ian, get a copy of Bob Shanebrook's book. A fascinating look at the complexity of the coating machinery/process.
    - Ian

  7. #17

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    Ha! Good point...

  8. #18

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    Pondering the R&D, testing, production, and waste that must be involved, it occurs to me that there must have been a spliced areas in the film web that had to be discarded with emusion on them, beginnings and ends of run pieces discarded, along with leftover coating "syrup". And all the fil from laboratory test runs... on and on. I'd have to guess that there was a very high spoilage rate all told. And all this waste with silver, a precious metal, just going to waste. Kodak must have had a whole silver recovery department. I didn't even mention all the punched-out sprocket holes from 35mm film, all with silver emulsion on them. Come to think of it, did you EVER head of one "hanging chad" on a roll of 35mm film? I never did. I'll bet at one time, a 35mm film hole-punching machine must have spit out sprocket-hole confetti by the barrelful as fast as they counld hand-truck it away and bring up another bin. A lot of silver in all that.

  9. #19

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    Quote Originally Posted by Tom1956 View Post
    Kodak must have had a whole silver recovery department.
    They did have a HUGH silvery recover effort. The silver recovery operation at Kodak Park was sold off and is now Rochester Silver Works http://www.rochestersilverworks.com/

  10. #20
    Steve Smith's Avatar
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    Quote Originally Posted by Tom1956 View Post
    I realize computer technology is nothing to sneeze at, or belittle. I concede it does indeed take some fine minds and collaborative efforts in that field. That said, I simply do not have the awe or respect for Apple or Microsoft, et al; as I do for companies like Kodak, DuPont, and the likes of them. Probably never will.
    I work as an electronic engineer (but seem to do more mechanical engineering now) and I am always more impressed with the ingenuity shown in clever mechanical solutions to problems compared with electronic solutions.

    An example of this is the Compur type of shutter. Look inside and you will see a quite complex mechanism which was designed to fit in a small space and was drawn up without the aid of computer modeling or CAD. There was not much margin for error as each part would need tooling to make it so it had to be close to right first time.

    Compare this to an electronic timer controlling a servo to open and close the shutter - a trained monkey could design that!


    Steve.
    "People who say things won't work are a dime a dozen. People who figure out how to make things work are worth a fortune" - Dave Rat.

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