New TMAX 100, UV & VDB

Back in March there was a list discussion regarding a change in the film
base of TMAX 100 with the result that the film now blocks a significant
portion of an ultraviolet exposure. This renders the film undesirable
for printing alternative processes such as Pt/Pd as reported by Sandy
King and several other list members. Today I am able to add some data
regarding the Van Dyke Brownprint process.

I ran into trouble yesterday helping a student do a Van Dyke Brownprint
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:
http://my.net-link.net/~jsmigiel/images/iechnical/VDB_TMAX.jpg

Bye bye TMAX.

Joe
Received on Fri Oct 15 17:14:58 2004