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  1. #11
    dwross's Avatar
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    Quote Originally Posted by Hologram View Post
    I actually did make some AgX emulsions I coated on PET film – very few on TAC also (It turned out to be difficult to get small quantities of TAC). One problem in the area I am interested in, holography, is that the usual PET (as well as a great many plastic) films are optically active, birefringent. They change linear to random polarization. This leads to severe “cosmetic“ defects on the holograms. Hence, PET film definitely is not my first choice. My assumption though was that for photographic applications this will not be of an issue.
    I'm sorry I've somehow missed the posts about your emulsions. I love reading about other people's efforts and I try to keep my eyes open for the opportunity. Are you going to try on the Melenex, or does it interfere with holograms, too? What's TAC?

    Your comment reminded me of a 'just-for-fun' I recently saw.
    http://blogoscoped.com/files/stripes.html

  2. #12

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    Quote Originally Posted by dwross;713579 [/QUOTE
    Are you going to try on the Melenex, or does it interfere with holograms, too? What's TAC?
    I understand Melinex, Cronar, Mylar etc. are all about the same stuff, polyethyleneterephtalate, PET.
    Due to the ”cosmetic” issue I cannot use them for regular work.

    Quote Originally Posted by dwross;713579 [/QUOTE
    What's TAC?
    TAC is cellulose triacetate, the most common (photographic) film base material.

  3. #13
    dwross's Avatar
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    Thanks for posting the definitions, including PET. I had meant to ask about that, too, but I was time-sharing my brain with cooking for Thanksgiving. Fortunately, I don't think I added silver nitrate to the pumpkin pie!

    I'm 'old school' science writer. Even with Google and Wikipedia at our fingertips ready to answer questions, I like to see a Three Letter Acronym (TLA) spelled out at the beginning of a new communication. APUG can be a great place for education if we avoid in-group talk.

    Quote Originally Posted by Hologram View Post
    I understand Melinex, Cronar, Mylar etc. are all about the same stuff, polyethyleneterephtalate, PET.
    Due to the ”cosmetic” issue I cannot use them for regular work.
    About your emulsions: Can you make any meaningful progress on your explorations with the materials readily available to you? This is a question I'm trying to hammer out for myself. How much can we learn - now - so that we are ready to leap forward when a crucial material or piece of the data puzzle comes our way?

    Denise

  4. #14

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    Quote Originally Posted by dwross View Post
    Thanks for posting the definitions, including PET. I had meant to ask about that, too, but I was time-sharing my brain with cooking for Thanksgiving. Fortunately, I don't think I added silver nitrate to the pumpkin pie!

    I'm 'old school' science writer. Even with Google and Wikipedia at our fingertips ready to answer questions, I like to see a Three Letter Acronym (TLA) spelled out at the beginning of a new communication. APUG can be a great place for education if we avoid in-group talk.
    I wholeheartedly agree.



    Quote Originally Posted by dwross View Post
    About your emulsions: Can you make any meaningful progress on your explorations with the materials readily available to you? This is a question I'm trying to hammer out for myself. How much can we learn - now - so that we are ready to leap forward when a crucial material or piece of the data puzzle comes our way?
    I guess it's safe to say that progress can be made with the materials I've access to – as long as these materials remain available. Here in Europe, buying photo chemicals becomes more and more difficult.

    It turned out to be rather tricky to get consistent emulsion batches. This may be particularly true for the small quantities I am dealing with (100ml of emulsion only).
    Coating layers of uniform thickness may be another challenge sometimes – given I've to concentrate my emulsions through a freezing/thawing cycle in order to increase gelatin/AgX concentration. This occasionally causes somewhat unpredictable results.

    My emulsions are very simple. They involve no dopants etc. The only “sophisticated” part consists in adding a small quantity of KJ. And then, prior to use, I apply a 1% ascorbate pH6 (reduction) sensitization bath.

  5. #15

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    Perhaps I am just uninformed here, but I wonder...who makes the subbed base stock for the worlds film makers such as Ilford, Kodak, Foma, Filmotec, Gevaert, etc? Couldn't there possibly be found another vendor for small quantity, since it is still made in large quantity for commercial film production? I wonder if a small quantity of subbed base could be purchased from a company such as Ilford?

  6. #16

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    Quote Originally Posted by Hologram View Post
    The only “sophisticated” part consists in adding a small quantity of KJ.
    Before anyone asks, "KJ" is potassium iodide in German.

  7. #17
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    Quote Originally Posted by Kirk Keyes View Post
    Before anyone asks, "KJ" is potassium iodide in German.
    Ahhh yes, I remember a heated argument with an APUG member who insisted that a particular formula had no iodide. The formula clearly had KJ addition in it. Oh well.

    As for making support, Kodak and Fuji (last I heard) made their own support on huge casting wheels. Another manufacturer was Dupont and another was ICI in London. So, there are few manufacturers and there are many many types of support and subbing that can be placed on them.

    The particular Melenex supplied by the Formulary uses a subbing that is tailored to work with dyes and emulsions. Many other subbed Melenex supports absorb stains and dyes and are therefore useless with some photographic processes.

    PE

  8. #18
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    I found some of the patents for Melenex a while ago, and it appears that the subbing compound is added during the manufacture of the polyester film base itself, and not afterwards.

    When I looked at other patents regarding subbing polyester after the manufacture, there was one in particular that mentioned that their subbing compound passed the dry and wet adhesion tests very well. However, the test emulsion they used contained congo red dye, and had stained the subbing compound.

    My question is...if we are coating a basic B&W emulsion, would we have to be concerned with staining? If sensitizing dyes are added to the emulsion, would they stain enough to cause difficulites, if at all? If we do not have to be as concerned with staining, as with dye transfer, can we use a similar method of subbing polyester?

    Bob M.
    Last edited by rmazzullo; 12-01-2008 at 03:12 PM. Click to view previous post history. Reason: corrected typo.

  9. #19
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    If a subbed film can be stained by dyes, then there is a chance that sensitizing dyes can get into the support and stain it. So, the answer is that it depends....

    PE

  10. #20
    AgX
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    Quote Originally Posted by PHOTOTONE View Post
    Perhaps I am just uninformed here, but I wonder...who makes the subbed base stock for the worlds film makers such as Ilford, Kodak, Foma, Filmotec, Gevaert, etc? Couldn't there possibly be found another vendor for small quantity, since it is still made in large quantity for commercial film production? I wonder if a small quantity of subbed base could be purchased from a company such as Ilford?
    There are at least two manufacturers of photo-grade film base in Europe:

    -) Agfa : PET

    -) Opco (an Agfa spin-off) : TAC

    Though both sell masterrolls only…


    Agfa of course get their PET base from themselves (they don’t coat on TAC).

    IlfordPhoto and Filmotec get their TAC from Opco.

    Ferrania might be casting TAC for their own use.
    Last edited by AgX; 12-01-2008 at 05:11 PM. Click to view previous post history.

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