Harry Callahan
Member
No; there you have it - I had longitudinal streaks. That's a VERY significant difference. Overall, the geometry of the defects look totally different if you examine them closely and I'm pretty sure that if you were to measure them, they'd also turn out to be quite different. Moreover, the defects in the film I processed were only in high-density areas; here they also affect dmin, suggesting they are of a very different nature.
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I said:
...You had streaks, which could be a coating-defect, but you also had cloud-like spots - and loccdors film is full of them. As he has more on his 120 as you had on your 35mm film, pressure can be a reason...
I am talking about the spots here. You even talked yourself about "insular spots", post #42 :

Fomapan 400 coating defects 35mm factory-confectioned
👍 I'm not going to claim to be the most fastidious of darkroom practitioners. I'll often mix powders up just before use and end up with maybe a bit of some undissolved chemical in the developer. I generally filter the developer through stainless-steel mesh but that doesn't mean much. So I...

Also the picture of the mountain in the snow has very few shadow areas and is lower resolution. I think i can see some lower-density-spots on the mountain on the right, but i cannot be sure.
Also if these lower-density spots are produced by pressure, these longitudinal streaks could be produced by the light seal of the 35mm-cartridge. 120 film does not have to squeeze through such a gap, which could explain why loccdors film does not show streaks but only spots.
But indeed, on loccdors film dmin also is affected which does counter my theory.
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But not impossible; we've seen many examples in recent years of Harman and Kodak film that was fresh and within date and affected by backing paper offset problems. It's a common problem!
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Yes, it`s not impossible - but i am wondering about two things:
Can these lower-density defects be overcome and
Where do they come from at all.
As loccdors 120 does show similar spots, but a lot more of them than your 35mm film, pressure still is a possible reason for them. And you said yourself that Fomapan 400 has a softer topcoat.
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I assume a soft topcoat is easier to compress.
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There is a little sarcasm in this statement... i assume film gelatin is complicated, but the softer a material is the easier it can be compressed usually. Or is softer gelatin harder to compress than harder gelatin?
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No they would not!
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If this is a coating-defect lower density spots and streaks would mean fewer emulsion in these areas. Then these areas couldn`t develop proper density because there isn`t enough emulsion and grain to build up proper density.
As i said, on very big lower-density-spots, under high magnification, a recess in the emulsion should be visible.
Ok, unless there is fewer emulsion but more topcoat on this spot. But to even out, fewer emulsion had to be coated and at the same time more topcoat, at the same spot.
Is this possible?
I cannot do all the empirical evidence nor work myself into professional filmcoating. That`s why i came here, to the experts. But as you mistook my theory for pressure-exposure (several times) i kept insisting, as that`s about all i can do.