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  1. #61

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    A 100 speed emulsion in those 1920's books are not ISO speed. They are most likely H&D speed. 100 H&D speed is comparable to or slower than today's multigrade paper emulsion used as a negative emulsion. (There is no exact conversion factor to speak of, because they are measured with different conditions.)


    Quote Originally Posted by Donald Qualls
    I'm with Ole on shutters -- simple mechanical devices like these, that don't run continuously, can reasonably be expected to last centuries if cleaned and adjusted periodically. I have three from the late 1920s that are within 1/2 stop at all speeds from 1 to 1/200, and I expect them to be still usable after I'm long gone, unless they're destroyed by environmental insults. FWIW, I also own a mechanical clock from the same era, one that wasn't expensive when new, which does run continuously -- and which I've recently managed to adjust to the point of gaining or losing less than a minute a month, the same accuracy that used to be advertised for quartz watches. Same for glass -- American Civil War era lenses can still make fine images, 140 years later, and there's no reason to believe non-exotic glasses will deteriorate in normal storage and use for millennia; they'll be destroyed by rough cleaning or physically broken first.

    I have an electronic copy of a 1920s book on making emulsions, which includes the (1920s style) chemical names of the sensitizing dyes and very detailed process information. I can't see this as being beyond the ability of the kind of people who used to perform the experiments that got written up in Scientific American's, "Amateur Scientist" features; it's certainly simpler in many ways to make a gelatin-halide emulsion and coat it on glass, acetate, or polyester than it is to, say, extract and amplify DNA from plant cells (as I recall being done in one such article) or build a basement fusion reactor (as has also been done -- no, the rate of fusion is well below break-even, but they're working on it). The modern ISO of the emulsions covered in the book I have would range up to 100, possibly even 400 with the right ripening process (though it would be as grainy as old Royal X or 4275 Recording Film -- might not matter, if it were coated on 8x10 plates).

    What this won't be is cheap. Now, someone like me (with very limited disposable income) can pursue photography fairly seriously, as long as he's patient and mechanically astute, without spending a bunch of money (I probably spent less than $1000 in 2004 including all equipment purchases, film, and processing/chemistry). Once large volume manufacture of film ends, unless we have something akin to Star Trek replicators we'll be forced to spend lots of time and money just to create the medium to record the image. Our hobby will become somewhat akin to fireworks making -- dealing with chemicals that, though reasonably common on an industrial basis, are expensive and hard to get in small quantities, might be hazardous to handle, and will involve enough work for a single use that most won't bother. The difference is, you can still buy fireworks, most places (even if they're illegal) if you're not inclined to make your own. By the time most photographers are making their own materials, you'll only be able to buy them from someone who makes them by hand or in very small volume.

    Look at what Bostick & Sullivan get for carbon printing tissue that's not even presensitized -- and think what that would cost if it incorporated five times as many manufacturing steps, in the dark, and included silver as an ingredient instead of soot. That's what film will cost once it's made in runs of 100 sheets of 8x10.

  2. #62

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    Books published in the U.S. is in public domain if it was published before 1923.

    The emulsion books written by E. J. Wall contain a lot of errors, irrelevant suggestions, misconceptions, etc. and I do not recommend them. I have a copy of 2nd edition but it's pretty bad. It's useful only as a way to search for older literatures for historical study. Same applies to Baker's book.

    If you like to study the emulsion making in 1920s, I suggest to read Carroll's paper in J. Chem. Edu. Carroll was very knowledgeable at that time but that was before he worked for Eastman Kodak Company, so he could disclose much of his knowledge in published paper. Carroll's formula in that paper work reasonably well with some of photographic gelatins available today, but good results probably require some tweaking.



    Quote Originally Posted by Donald Qualls
    The link where I got the book has been gone for some time -- as I recall, it was the U. Mich. library, and they had a project going to digitize a bunch of old, out of print books, that was likely scotched by changes in the copyright laws such that they can't be certain a work published in 1925 is in public domain (and on their level, if they're not certain enough for their legal staff to bet their jobs, it's pulled). It's a very large HTML file with accompanying JPG images (charts and drawings, not photographs for the most part); the title is "PHOTOGRAPHIC EMULSIONS: THEIR PREPARATION AND COATING ON GLASS, CELLULOID AND PAPER, EXPERIMENTALLY AND ON THE LARGE SCALE" by either E. E. Wall or E. S. Wall (the scan is bad, shows as E. 3. Wall -- could also be E. G. Wall, I suppose).

    The basement fusion reactors were of the "fusor" design (on which you can find a number of web pages with a Google search) -- electrostatic confinement, deuterium fuel (though their plasma formation and confinement can be demonstrated without the risk of neutron irradiation using plain hydrogen), and in theory the possibility to extract fusion energy as a direct current between the core and the vacuum chamber shell. The biggest one I've heard of, anywhere, was in the range of a 24" vacuum chamber diameter; they're theorized to have a break even at around one meter confinement core diameter (which would be about a 2 m chamber) -- assuming one can make the direct current extraction work, find a way to trap the fusion neutrons (to avoid killing all organisms within a few hundred meters), keep the 3He cleared from the core and inject fresh deuterium, etc. The equipment is on the same order of cost and difficulty to build as an astronomical mirror aluminizing machine, but potentially lethal to operate...

  3. #63

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    Don't worry, much of emulsion making is described in literature. Certainly enough is written as long as b&w emulsions are concerned. Most recent advancement is written for color photography, but some of those new techniques can be applied to b&w emulsions as well.

    Kodak people may have strong internal barriers in terms of sharing information within them, but Fuji worked on research and development with huge teams, and people changed their role every 5-15 years. So many people know more than one aspect of emulsion chemistry. And Fuji (and ex-Fuji) people still publish their knowledge in scientific journals even in 2005. They are still doing basic science of silver imaging.

    Also, it takes a certain kind of skill to read useful info out of patents. Patents are usually applied as a "network" around each new breakthrough, and different people have different styles. But once you get the art of patent deciphering, you'll get a lot of info from them, especially if you cross-check patents and scientific papers.

    Plus, I'm not that old.


    Quote Originally Posted by Neanderman
    Emulsion making in concept is fairly easy. In practice, however, it is an incredibly complex undertaking.

    First off, you have the gelatin. It has to meet certain standards of purity -- meaning it can't have the wrong impurities, but it needs to have some of the right impurities. (Shortly after Eastman started manufacturing dry plates, he had a large batch fail. Investigation traced it back to the sulfur content of that batch of gelatin. This product failure played a large part in the formation of the Kodak Labs.)

    Once you have the gelatin, you have to very carefully and consistently add the other ingredients (i.e., the silver, the halide(s), the sensitizers, etc). Then you have to let the emulsion age for a period of time.

    Once it has aged, it has to be allowed to solidify. It is then shredded and carefully and thoroughly washed to remove all of the excess and byproduct chemicals.

    Then you get into coating...

    While much of the basic science of emulsion making is quite well documented in the literature, there is a great deal of proprietary, unpublished knowledge involved as well. Kenneth Mees addressed this in the preface to his book "The Theory of Photography" saying that he had to basically ignore that whole aspect of the science because much of his knowledge of it was acquired via his work for Eastman and was therefore nondisclosable.

    I have a great fear that, because so much of this is proprietary, it will be "lost" information should the major manufacturers cease manufacturing film.

  4. #64

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    There are lots of dyes that can be used for pan films. I can make t-grain emulsion, and theoretically, sensitize for panchromatic films. However, I am working in safelight using my own arms, so I can't handle pan emulsions. If you pay to build a facility for me, I can make it for you :-)

    The best I've tried so far is infrared emulsion (in green safelight). But this is still painful to make practically usable plates in very dim light (or the emulsion will fog).

    Quote Originally Posted by Jorge
    Making an orthochromatic film should not be very hard, it is making a fast speed (100 asa and above) panchromatic film with consistency that it is difficult.

    The dyes used to give film panchromatic properties are difficult to obtain and I imagine in small quantities probably very expensive. Sadly I think neither Kodak or Ilford would release their formulations even if they decided to quit making film altogether, so in essence you would have to re invent the wheel.....seems to me we will have to be happy with glass plates, but heck, if it was good enough for G. Eastman, it might just be good enough for us...

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