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  1. #1
    Photo Engineer's Avatar
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    New Kodak support decreases UV transmission

    I have verified that a new Eastman Kodak support, probably the one with the new antistatic properties mentioned as being used in the new 800 speed color film recently, contains an ingredient which increases the absorption of UV light.

    For those printing with UV light, this means that less UV will go through the film and that will increase exposure times.

    I had dismissed these rumors before until I could verify it myself, and I was able to get this information reliably this week, so I am passing it on to those who use Kodak B&W films for UV exposing. Don't be surprised if your exposure times increase.

    PE

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    If I were to use a film that shows no response to uv light and if it were to cost me, say 1/3 of a stop in film speed, I would consider to be a good trade off.
    Claire (Ms Anne Thrope is in the darkroom)

  3. #3
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    Quote Originally Posted by Claire Senft
    If I were to use a film that shows no response to uv light and if it were to cost me, say 1/3 of a stop in film speed, I would consider to be a good trade off.
    1/3 stop isn't even in the ballpark. It the absorption of UV light is anything like that found in the new 100TMax, any film exhibiting this property will be completely useless for any process where UV light is a significant part of the spectrum. If they began ruining TMY this way, for example, I would immediately switch to Ilford FP4.

    TMX negatives are completely unprintable for me on Azo, no matter what they're developed in.

  4. #4
    Photo Engineer's Avatar
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    My statement only referred to printing speed with UV light, not any camera speed effects.

    PE

  5. #5

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    Quote Originally Posted by Photo Engineer
    I have verified that a new Eastman Kodak support, probably the one with the new antistatic properties mentioned as being used in the new 800 speed color film recently, contains an ingredient which increases the absorption of UV light.

    For those printing with UV light, this means that less UV will go through the film and that will increase exposure times.

    I had dismissed these rumors before until I could verify it myself, and I was able to get this information reliably this week, so I am passing it on to those who use Kodak B&W films for UV exposing. Don't be surprised if your exposure times increase.

    PE
    PE,

    Will Kodak be changing all of its B&W films like this in the future? I would hate to buy a quantity of film only to find out later that it is completely useless for Pt/Pd printing or Azo work.

    Alan

  6. #6
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    Alan;

    I have no idea whatsoever.

    I don't know what products currently contain this new ingredient either.

    PE

  7. #7
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    Seeing is believing...

    Here are a couple tests I ran with van dyke brownprint chemistry, one of the UV-sensitive alternative processes. Printed at the same time you can see how TMX screens the UV compared to TMY and HP5+ films. (Except for the strip labelled "no film", the step wedges were in contact with fixed but undeveloped sheets of film as indicated.) There were rumours floating around that time that an isopropyl alcohol soak would remove the UV agent, but as you can see in the second test, there was no practical effect. After this, test I tried extending the alcohol soak up to an hour, still with no effect.

    The UV coating blocks about 4 or so steps which is equivalent to about 2 stops. That's turning a 20-minute contact print exposure to one requiring an additional hour (80 minutes). No thanks.




    I believe New TMX and New Plus-X (IIRC) were the two films with the new coating initially. Since Kodak made that move, I haven't trusted their products and have not purchased any LF or ULF films from them, instead switching my allegiance to Ilford and Efke.

    Joe

  8. #8

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    Quote Originally Posted by smieglitz
    I believe New TMX and New Plus-X (IIRC) were the two films with the new coating initially. Since Kodak made that move, I haven't trusted their products and have not purchased any LF or ULF films from them, instead switching my allegiance to Ilford and Efke.

    Joe
    So the alcohol soak is not very effective in removing the UV filter?

    Sandy

  9. #9
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    Quote Originally Posted by sanking
    So the alcohol soak is not very effective in removing the UV filter?

    Sandy
    Not effective at all that I could see. I used isopropyl for the recommended time of 5 minutes (I forget if the instructions I had called for diluting it) and when that had no effect I extended the treatment time to an hour using full strength store-bought isopropyl with no difference I could see.

    Joe

  10. #10

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    I suspect the main affect of increased UV absorption in the base will be more reliable scanning and printing. Kodak is already pretty good at that, but improvements are always welcome. Since the sensitive layers are coated on top of the base, camera exposure would be affected little if any. Aromatic groups absorb strongly in the UV, so a change to a base with high aromatic content or (and) a suitable absortive dye in the base would do the trick. BTW, the antistatic properties of the new base are great. The dust just falls off!

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