Quote Originally Posted by sandermarijn View Post
That's very interesting new input! If I understand correctly, you mention two possible causes for the marks, both with a root cause in something called 'pressure fog': 1. too much friction during the rolling up of the exposed film, 2. too much friction between film and guiding rolls.
Do I figure correctly that you did not find a solution? Me personally I don't see how I could prevent either cause.

Yes Philippe, it's a bit shitty to loose film. But if the problem is eventually solved then I will mind quite a bit less.

I don't entirely understand how you mean the plastic rails come into play. I do use plastic rails (Paterson), so I am quite interested in your thoughts. Can you elaborate?
It’s quit simple, when the film is in use and left for a few days in the camera, one of the rolls is still pressing the film against the edge of the camera’s frame, then a mark might occur.
This happens, in an other way although, particularly in the Linhof Technica 617. There, a thin steel roll is pressing the film against the rubber cylinder (connected to the frame counter).
But, again, this is very seldom and, as I said, the most of the cameras are NOT to blame, because it does not happen with other brands of film!
And, not only when the film is passive. When the film is transported, it ‚slides’ via the transporting system, over the guiders, the pressure plate, the camera frame and finally comes in to friction with the backing paper when rolled up.
In a certain sense, it occurs the other way around too, when unrolling the film for processing, then, even the fingernails can scratch the emulsion, what happened to me.

The reels, I used to work with, are the JOBO 2500 ones. They have something like really ‚wide lips’ at the beginning, and, believe me, they do scratch Foma film; again, other brands of film are not showing this issue!

It is the lack of a good protective layer on the emulsion that is causing the problem, and, IMHO, the rather rough and stiff backing paper as used in conjunction with Foma roll-films.
What I did not tell, and apologise me fort this forgetting, is that my experiences are solely with 120 roll film.