35mm bulk cartridges: How long do they last?

AgX · Jun 26, 2010

karthik said:
It is possible that I have been leaving the Paterson tanks sitting in bright light (an overhead bulb) for too long without keeping the lid on, and the light trap isn't perfect, especially with light coming directly from above?

But how could affect a non-lighttight developing tank just the rebates of the film?
(I'm referring to marks like in post #26.)

erikg · Jun 26, 2010

karthik said:
I suspect that at least in my case the fogging happens after I load the film onto the developing reel. I am using a Paterson 2 reel tank. Here are my reasons:

(a) The marks are periodic. So the film is more likely to have been in a rolled state when the fogging happens.

(b) The marks only occur in the innermost (i.e., last frames to have been shot) few frames. But the centers of the reloadable canisters are among its most light-tight parts (the central post has a flange at both ends, making it more likely for the outermost parts to fog, if at all). I originalyl suspected the film-leader retriver - but that would affect _all_ frames, not just the innermost few.

(c) It happens with both camera bodies I have, but not on every roll. So the light leak is neither in the cameras, nor in the loader.

It is possible that I have been leaving the Paterson tanks sitting in bright light (an overhead bulb) for too long without keeping the lid on, and the light trap isn't perfect, especially with light coming directly from above?

If that is happening, you need a new tank. The cap shouldn't be needed to keep the tank light tight. The top of tank and the core fit together so light can't pipe directly inside. I think it is more likely the fogging is happening while the reels are being loaded, maybe from a low level light source that you don't easily notice. Good luck!

As AGX points out above, if it was the tank it would be more wide spread, and much heavier on the top reel in the tank.

srs5694 · Jun 26, 2010

A simple test for a light leak in a tank: Put a snip of film or paper in the tank, leave it in room light for, say, an hour (or maybe longer for paper, which is slower than most film), and then develop it, preferably in some way that doesn't involve the tank you're testing. (I'd therefore favor using paper and developing it in a tray. OTOH, if the tank is leaking only red light, a paper test might give a false negative result.)

fehutchings · Jun 26, 2010

Bulk Load Cassettes

Used a lot of re-loadable cassette back in the 80's (long time ago)... Found that the cheaper ones - metal or plastic - tended to develop light leaks because of deterioration of the fiber material across the "mouth" of the cassette where the film slides in and out of the cassette. The wear usually happened at the edges, hence the light leaks would be in the sprocket area along the edges of the film with some streaking onto the negative. Just to be on the safe side see if you can locate a few "expensive" cartridges where the end caps screw on. These will also have a better quality fiber lip across the mouth of the cassette. Any little bit of grit that gets under the "snap cap" will also cause the light leaks you are experiencing. Pay close attention to reply #3 from 'Monophoto'. What he says pretty well mirrors my own experience.

karthik · Jun 26, 2010

AgX and ericg: You are right - it wouldn't affect only the rebates. But I think it would be a good idea to do a test with a small strip of film.

35mm bulk cartridges: How long do they last?

AgX

erikg

srs5694

fehutchings

karthik

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