Anti-Halation backing on TMAX 100greenspun.com : LUSENET : Large format photography : One Thread
When I develop TMAX 100, or rather, when I fix it, the film sometimes sticks to the side of the processing drum and has a faint blue color in a few spots. I'm guessing this happens because the fixer has trouble getting to the the backing and dissolving away the anti-halation layer. What's odd is that within seconds of placing the negative into the wash, the blue intensifies significantly from an almost unnoticable hue to a reasonably significant shade. I usually end up putting the film back into fixer, where the color disappears almost immediately, only to return (less intensely) when I put the negative in the wash. Can anyone out there tell me why this happens? It's not a critical problem, but it is becoming a pain.
-- Winston Chang (email@example.com), December 01, 2000
I don't know why the color is coming and going. Perhaps your fixer is exhausted?
In any case, try hypo clearing agent, perma-wash, or orbit bath. These will ususally clear an anti-halation dye.
If your using a staining developer (like pyro), however there might be something else going on relative to the staining.
-- Charlie Strack (firstname.lastname@example.org), December 01, 2000.
Unicolor drums have ridges along the walls so that the solutions can get around to the film base side; don't use a smooth-wall drum.
Also, the use of an HCA in a tray before the wash would probably eliminate the problem.
-- John Hicks (email@example.com), December 01, 2000.
Winston, The dye that remains on the film backing is most likely an indication that chemistry did not fully circulate in that area. I have seen the same problem with old Nikor sheet film tanks where the support bands occassionally touch the base of the film. The answer is pretty easy. You need to make a solution of Sodium Sulfite, which is available in powdered form from Kodak and others, and immerse the film in it using a tray. When the stain is gone, you're ready to refix and wash. Now the next question is probably going to be what strength of solution do you need? I honestly don't know. What I've done is to dissolve about a teaspoon of the powder in about a quart of water. It seemed to work slowly enough to indicate I wasn't over doing it, a couple of minutes. Perhaps some others that contribute to this forum and have experience clearing Poloroid PN might have a more scientific answer. I understand that Sodium Sulfite is the stuff they use to do that. Good luck.
-- Robert A. Zeichner (firstname.lastname@example.org), December 02, 2000.
Use 20g sodium sulfite to make a liter of HCA; that's slightly less than a level tablespoon. Strength isn't remotely critical.
-- John Hicks (email@example.com), December 02, 2000.