Discussion in 'Alternative Processes' started by Ray Bidegain, Sep 6, 2004.
Did I miss something about the new 100 tmax having a base that blocks UV?
Yes you did, apparently Kodak has incorporated a UV coating and the film is no longer useful for alt printing.
The fact that the new Tmax 100 has a base coating that blocks UV light to the tune of about log 1.0 has been discussed on several lists. That is more than three stops of density, which means a three stop increase in exposure times for UV sensitive processes. That changes a basic two minute exposure into one of 32 minutes.
Well that explains it.
I ran into trouble the other day helping someone do Van Dyke Brownprints for the first time. His exposures were well beyond what normally should have produced a good print with a negative falling within the recommended density range for VDB. At that point I noticed the 4x5 negative had a textual film code for "TMAX 100" next to the notch code and I realized this must be the new TMAX 100 film. He brought the box in today and sure enough, it was the new flavor of TMX.
I then ran an exposure test using a Nu-Arc 26-1K mercury plate burner. My normal exposure for double-coated VDB on Cranes Kid Finish and an HP5+ negative is around 400 units of exposure. I gave the this test 500 units which took 29 minutes.
For the test I attached a Stouffer wedge to a sheet of new TMAX 100, another to a sheet of old TMAX 400, and another test wedge in direct contact with the paper (i.e., no film in the UV path) in the middle of the test image. The visible FB-F as measured on a transmission densitometer was 0.02 for both films, neither of which had been developed, only fixed and cleared.
My results indicate the new film is blocking 4 steps or ~2 stops exposure at this level of 500 units total exposure. To compensate for this, the 500 unit exposure would need to be extended to 2000 units and that would take nearly 2 hours to expose.
If interested you can view the test image at:
Bye bye TMAX.
On another forum it was reported that the UV coating can be removed by soaking in an alcohol solution, after processing is completed. I have not tried the soak myself but several people report that it works.
am I the only one that finds this totally insane? Does Kodak R&D even use the products they market? I doubt the UV would be an issue on roll film, but for Sheet film, C'mon folks!
Do you recall which alcohol was used? Are we talking methanol, ethanol, or hopefully isopropyl ?
Do you have the link to the thread on the other forum?
Go here for more info:
I just printed my first Pd/Pt prints last weekend using Tmax 100 negatives. The negatives were made using the repackaged Tmax 100 with the new developing times. The film was developed in D-76 using the standard procedure, no tricks. I exposed the negative to the sun for 1.5 minutes after having made a test strip with a maximum time of 18 minutes. The sun was just about directly overhead on a cloudless day. The print looked great to me, but to be sure, I showed it to my neighbor who is an experienced Pt/Pd printer. He said the print was fine, not underexposed. He was surprised by the 1.5 minute exposure time. The 21 step tablet placed next to the negative had 13 distinct steps - sometimes it looks like 12 when the viewing light is different.
I don't know why I'm not having the UV problem described. Would using the sun have anything to do with it? Obviously I'm not disappointed, but it's strange that I'm not having the problem.
The fact that you are exposing with the sun may indeed be the reason the UV base is not having any impact on your exposures. The UV blocking of TMAX-100 is in a fairly narrow range of the UV wavelength while Pt./Pd. is sensitive to light from well outside this range. The sun provides radiations in a very wide band on both sides of the UV filter and this could well explain why it is more efficient in printing Pt./Pd. than the artifical lights we normally use in exposing this process, which emit light in a fairly narrow band of wavelength.
On the other hand, direct sun puts out a lot more radiation than most artifical light sources so the reason for your short exposures could the power of the light source.
If someone has a sample of the "old" and the "new," then I could run a test of the UV transmittance of both and post the results. It would be best to use developed and fixed, but not exposed, film. If that is not possible, then I could work from the typical negs that folks have created during normal use. The test is non-destructive and of course I would exercise all due care, but I would rather not have someone's latter day equivalent of Moonrise! Please PM me if you have examples of both the original and the "UV blocking" film.
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