New Kodak support decreases UV transmission

Discussion in 'Alternative Processes' started by Photo Engineer, Jun 3, 2006.

  1. Photo Engineer

    Photo Engineer Subscriber

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    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
     
  2. Claire Senft

    Claire Senft Member

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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.
     
  3. c6h6o3

    c6h6o3 Member

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    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. Photo Engineer

    Photo Engineer Subscriber

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    My statement only referred to printing speed with UV light, not any camera speed effects.

    PE
     
  5. Alan Davenport

    Alan Davenport Member

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    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. Photo Engineer

    Photo Engineer Subscriber

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    Alan;

    I have no idea whatsoever.

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

    PE
     
  7. smieglitz

    smieglitz Subscriber

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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.

    [​IMG]
    [​IMG]

    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. sanking

    sanking Member

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

    Sandy
     
  9. smieglitz

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    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. nworth

    nworth Subscriber

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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!
     
  11. Donald Miller

    Donald Miller Member

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    Said what?

    Have you considered this effect on alternative process printing where long exposures and UV light sources are the norm?
     
  12. clay

    clay Subscriber

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    Okay. I am almost afraid to ask. Has anyone printed platinum using a negative from the just-delivered batch of Kodak TMAX400 ULF film? If they changed bases for this run, I just wasted a lot of money....
     
  13. c6h6o3

    c6h6o3 Member

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    It'll be more reliable, all right...reliably bad. As I said above, TMax 100 negatives are unprintable on Azo. Any film to which they do this will be ruined for many of us. Not an adjustment to our process, not an inconvenience. Ruined!
     
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  15. c6h6o3

    c6h6o3 Member

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    Ron:

    Can you try to find out through your contacts at Kodak? This is really important.

    Thanks for all your informative posts, BTW.

    Jim Shanesy
     
  16. roteague

    roteague Member

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    I suspect quite a number of color films have this as well, but guess that wouldn't affect you guys.
     
  17. sanking

    sanking Member

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    Clay,

    That issue came up last year before production of the film and Michael Kadillak verified with Kodak that the new batch of TMAX-400 would be on the same base that has been used in the past. He mentioned this fact in a thread that appeared on the LF forum sometime late last year.

    Sandy
     
  18. clay

    clay Subscriber

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    I remember the thread, but with the attention to detail that Kodak exhibited in boxing up 10 sheets of 7x17 film in a 16x20/25 sheet box, the whole thing has me a little spooked. I am going to load up some holders and do some test shots to see what we were delivered. It may be a week before I get around to the printing part, but I will let everyone know.

     
  19. Photo Engineer

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    Jim;

    Just getting the information I reported here was a bit of a pain. And, it took way too long from my point of view. I think that EK should shoulder this responsibility and report the changes to the consumer.

    I'll do the best I can, but for the information of those using Azo, I understand their pain, but OTOH, I scan my analog negatives and slides and make LF digital negatives for contact prints. So, I actually never ran into the problem.

    And, for those who think it a 'sin' to print from digital LF negatives, well, I don't have an 8x10 camera. So, that is the only way I can take a 35mm or even a 4x5 negative and make an 8x10 cyanotype or Azo print.

    Otherwise, I make enlargements and UV sensitivity with enlarging paper emulsions is not an issue.

    PE
     
  20. nworth

    nworth Subscriber

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    I don't think it really applies, or at least I don't think it applies yet. For alternative processes, we use very large negatives, which are usually still triacetate based. The new UV opaque bases may make making interpositives and enlarged negatives a bit easier. If you ever do get into alternative printing with film on a base with a short UV cutoff (e.g polynaphthalate or polystyrene), all may not be lost. There is usually still significant transmission from about 380nm through the visible with these plastics, and the alternative processes have very significant sensitivity in the blue, violet, and very near ultraviolet regions. (This is why 360BL lamps are better than BLB lamps.) Exposures will be longer, but probably not excessively so.
     
  21. sanking

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    If the new UV support base is anything like the base of the new TMAX-100 your speculation is entirely wrong. I tested the new TMAX-100 film with various light sources, including BL and BLB tubes, and with a NuArc 261K that produced a lot of radiation in the visible spectrum. In evey case the end result was a loss of printing speed of about three full stops compared to other films.

    Sandy
     
  22. smieglitz

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    It sure applies to new TMAX 100. It has become pretty useless for alternative process printing IMO.

    That's relative. If you are enlarging with an average exposure of 20 seconds, losing 3 stops because of the film base makes your new exposure 2 minutes 40 seconds. That's tolerable. But, if you are contact printing using UV and your exposures average 20 minutes with the new film base you are now looking at 2 hours and 40 minutes for the exposure.

    And, I don't suspect the slight sensitivity of these print emulsions will be impacted much by the blue exposure. They are proportionally less sensitive to blue than to UV IIRC so the visible exposure won't compensate for the loss of the UV exposure.

    Sandy, BTW the VDB test I posted earlier was also done with a Nu-Arc 26-1K but with that process it appears the loss in printing speed was slightly more than 2 stops. With which processes did you test the various exposure sources and find a three-stop loss?

    Joe
     
  23. Donsta

    Donsta Member

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    I haven't printed anything from negatives shot on the new Tmax 400 order - but I have processed a couple of 8x20 negatives (yes, blowing a $9 sheet to test each side of each holder is excessive, but it's all I had) to test a batch of new filmholders and popped them under my 361T densitometer in UV mode - there is NO problem.... It's just the same TMY as it always has been - excellent UV transmission. Don't panic Clay...
     
  24. clay

    clay Subscriber

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    Thanks! That is good enough for me. I use the same densitometer, and I have found it to indicate UV transmission density very accurately.
     
  25. reggie

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    Sandy:

    Will the ULF-28 put out enough UV light to shorten the exposure times?

    -R
     
  26. nworth

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    I haven't tried contact printing the new TMX. The increase in exposure that Sandy notes doesn't make sense to me, but I trust his work. Three stops could, indeed, be bad for alternative processes. Someone noted that TMY has pretty normal transmission in the UV and should print normally. That agrees with my experience. But TMX and TMY are different beasts, and TMX may have changed bases if a new batch was made.

    One question that has arisen is what and where the filter is. If it is separate and on the back, you may find a solvent for it. If it is on the film side, dissolving it may be a problem. If it is the base itself, you're out of luck.

    Aromatic compounds have very high extinction values in the UV, 30000 or more being common. The extent of the problem will depend on what the cutoff wavelength is. Generally the cutoff is pretty sharp, but the slope and spikiness in the spectrum may have a little effect too. I recall that naphthalene derivatives have a praticularly long cutoff. Many even appear yellowish. APS films used a polynaphthalate base. It had many advantages, including staying flat and dust free. Could this base have migrated to LF?