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Thread: Film emulsions

  1. #11
    Photo Engineer's Avatar
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    Melted gelatin has good laminar flow. That is how current 'slide' coatings are made in production. Viscoscity can be customized by changing concentration or temperature.

    Sensitzing dyes cannot be added to metallic or colloidal silver. This is similar to trying to sensitize a Daugerrotype. Many have tried, and all have failed.

    PE

  2. #12
    r-s
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    Quote Originally Posted by Photo Engineer View Post
    Melted gelatin has good laminar flow. That is how current 'slide' coatings are made in production. Viscoscity can be customized by changing concentration or temperature.
    Well now that gives me some hope! I may spend some quality time with some ABS plastic and pipe cement, and see what I can whip up! (The state of my health is such that I do not forsee a happy outcome to any technique requiring the sort of manual dexterity requisiste in the blade system. Also, the former software engineer in me makes me tend to try to work up self-regulating systems that take care of the "fine tuning" on their own.)

    Quote Originally Posted by Photo Engineer View Post
    Sensitzing dyes cannot be added to metallic or colloidal silver. This is similar to trying to sensitize a Daugerrotype. Many have tried, and all have failed.
    Well, look at how many times it took Edison before he came up with a viable incandescent filament. (And just to be fair and balanced look at how his rival Tesla was unable to persuade anyone of the viability of AC power transmission systems.)

    I'm wondering if perhaps during the creation of the CS, the electric charge in the water might be able to be used to perform something akin to anodization of the dyes (bonding them onto/into the grains as they form)? I know that the size of the silver granules can be regulated via voltage, current, and time duration (the longer you run the process, the more the conductivity of the medium goes up, and the larger the grains become). I believe it's possible to create some fairly large grains, if desired. (Generally the goal is to create the smallest sized grains as possible, with larger grains being an indication of the process having gone awry, but most of the people using that process are not using it for photographic purposes.)
    Last edited by r-s; 11-03-2006 at 10:11 AM. Click to view previous post history. Reason: Clarification.

  3. #13
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    The binding of a sensitzing dye to the surface of a silver filament or deposit of any sort would be disrupted by oxidation and the dye would be removed, and then the silver halide would form in the presence of a very low concentration of dye, if I understand your process properly.

    It would be more useful to form the silver halide and then dye it, even in situ although the speed would be low.

    Remember too, that Edison was not a very nice person, but persistant. It took him years to develop his electric light. And, Tesla was also in favor of using the natural energy of the earth. He claimed to cause earthquakes by vibrating metal bars at the natural frequency of the earth and he said he could broadcast energy waves all over the earth to power equipment or to be used as weapons. Some things work and some don't. Give it a try and see what happens.

    PE

  4. #14
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    Quote Originally Posted by Photo Engineer View Post
    R[... Tesla] said he could broadcast energy waves all over the earth to power equipment [...]
    That actually would work - except the system would be rather inefficient, and in some places the RF voltage would be so high you would draw arcs randomly.

    He was a brilliant man, who had NO people skills, and became the architypical "mad scientist" - later in his life he would have a birthday press conference and say things like "...They said it wouldn't work... but I'll show them! My death ray will transform the world!!!" all wild eyed.

    Transformed our world (Radio, Radio control, AC power, etc.) but died penniless and alone. Sad. If only he had become a photographer!
    B & D
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    Quiquid Latine dictum sit altum viditur

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    Quote Originally Posted by Bromo33333 View Post
    That actually would work - except the system would be rather inefficient, and in some places the RF voltage would be so high you would draw arcs randomly.

    He was a brilliant man, who had NO people skills, and became the architypical "mad scientist" - later in his life he would have a birthday press conference and say things like "...They said it wouldn't work... but I'll show them! My death ray will transform the world!!!" all wild eyed.

    Transformed our world (Radio, Radio control, AC power, etc.) but died penniless and alone. Sad. If only he had become a photographer!
    Yes, very sad. His patented earthquake machine was never made to work by anyone but him, but he said that it brought down a building and caused an earthquake in Denver(?). They recently tried to duplicate some of this work on Mythbusters on the DISC channel.

    They drew some rather nasty cartoons of him in his later life.

    PE

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    Developing 'home made' gelatin emulsions

    Not to change the subject back to the original thread, but would I be correct in assuming the gelatin emulsion made by Phto Engineer would be developed using a normal B&W process, like D-76 -- or would you use a stronger developer like Dektol?
    Also, have you ever tried doing direct silver positive development to produce an ambrotype effect? If so, how did you do it?

  7. #17
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    I have used Dektol 1:3, 1:2 and 1:1 right now, but that is not to say that D76 could not be used. I just keep Dektol around for standard testing and use that by habit.

    I have used other developers to good effect, but right now Dektol 1:3 for 3' looks like a good film develper to me.

    There is no reason that a silver positive could not be made with appropriate processing. I would use D19 or D8 or D11 (a high contrast developer) for the first developer and then a non-rehal bleach, a clear and redevelopment in the light, just as in a conventional process.

    I have no intention of producing a direct reversal emulsion however. This is an emulsion that gives a reversal image directly from a single development step.

    PE

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    '1 have no intention of producing a direct reversal emulsion however. This is an emulsion that gives a reversal image directly from a single development step.'


    Why not? You could bottle it and make a fortune -- like Rockland Colloid did with Liquid Light!

    And just to show my ignorance (as if you couldn't see it already), how does a direct reversal emulsion work?

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    There are several types of reversal emulsion that rely on different mechanisms. This was one area that I didn't get into much as they were pretty much history by the time I enetered emulsion work. They were used in the Kodak instant film primarily.

    The most prominent relied on a core shell emulsion which trapped the negative image internally and used a nucleating agent to 'fog' the surface to yield a positive image. The nucleating agent was (IIRC) a hydrazine derivative called a hydrazide. Since I did my thesis on hydrazides and hydrazones as well as azo chemistry, I followed it pretty well, but have forgotten most of it.

    I have some notes here somewhere if you are really interested, but I have not looked at them for years. If you are interested, I could look them up, but I can't promise how complete they might be. Sorry.

    In any event, I have enough on my plate right now without getting into these rather more complex emulsions. I want to make 3 emulsion types and do them well and do them simply.

    1. Contact emulsions in 3 grades. Pretty much done. They are equal to or better than AZO.

    2. Enlarging emulsions in 3 grades. I have 2 out of 3, working on the next one. These are a cross between Brovira and Kodabromide.

    3. Negative film emulsion with ortho sensitivity and about 25 - 100 speed. I'm getting 40 speed regularly with high fog and low contrast. I'm working on this.

    4. Move on to color??????

    Enough for me do you think?

    PE

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    Time to clone you Ron.
    Robert M. Teague
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    "A man who works with his hands is a laborer; a man who works with his hands and his brain is a craftsman; a man who works with his hands and his brain and his heart is an artist" -- Louis Nizer

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