II also have a concern that it might wear out the mechanics of my Hasselblad film backs prematurely as there is a fair amount of abrasion going on.
ICould this abrasive paper also be where 'static' charge marks are making there way onto the film, or are they actual scratches...??
Rolling two bands on one axle is always causing a kind of friction between them due to the slight but present difference of winding speed.
I bring this up not to question your conclusions but merely because these type of issues make me nuts as there often remains some doubt, driving me to keep trying to make something work. Maybe I think, it is just something I'm doing...
--erik
In the old days we had emulsion numbers on batches of pro film and it sure would be nice to compare emulsion numbers. From what I see here I'd have to say these are mechanical scratches and not chemical/water problems. I'd say the rollers on the film slitter at the plant could use a good cleaning.
This is a complete guess on my part, and I am
sure someone like PE would have a better idea
of the cause, but I am thinking the problem has
something to do with how the emulsion dries on
the substrate, and maybe with flaws of some sort
in the substrate, that causes these checks to open
up as the film dries after coating. If it was from
the cutting, one would expect a more predictable
pattern. And the imperfection appears across
emulsions as well as formats -- I am seeing it in
35mm Foma 200, while the OP sees it in 120 Foma
100. The coating and drying are the processes
common to both films.
I hate to blow your explanation but it's not the backing paper.
I shoot Foma 200 in 35mm and I find the same artifacts. I am
attaching a raw scan from a roll I just shot through a Tenax II
in which you can see the same artifacts. Obviously, 35mm film
does not have backing paper.
Back to the drawing board.
PS: If you want to see the final image, you can find it at
Dead Link Removed
Now I'm really paranoid because I roll my own and we all know the cassettes are never pristine when you reuse them.
Other possibilities:
1) have you tried to use a hardening fixer?
2) in 35mm friction of the emulsion on the light trap, with dust grits embedded (not probable);
3) I would exclude the particles in the tap water because these scratches would otherwise have a random pattern;
4) the simplest explanation is: poor manufacture from Foma. Look no more.
I would agree with the first statements that involve the presence particles in tap water that would complex with dissolved silver and would make this marks. That would also explain why Sasnders observed such marks with 35 mm films: foma emulsion are sensitive to such complexes.
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