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 would reverse the film loading to compensate.
Fomapan 400 coating defects 35mm factory-confectioned
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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 would reverse the film loading to compensate.
Interlayer drying marks are highly likely then. You don't see them on the surface necessarily under oblique light - they affect layers below the supercoat and are caused by too hot a dryer for your RH % causing the top layer to dry faster. Some films are much more susceptible to them than others. There is information about the how & why, deep in the old documentation for Photo Flo and a few other places in Kodak et al's old technical data for labs/ graphic arts. They are exceedingly annoying, but if you catch them fast enough you can usually get rid of them by a quick re-soak in wetting aid - if not, they're there forever. If you used a staining developer, some of them have known problems with Foma films (runaway dye formation in one case). The only really significant fault other than the inherent sharpness/ granularity/ image content transmission/ latitude limitations of the material that I've encountered with Fomapan 400 was the Anti-Halation backing leaving messy speckles after processing that they disclosed a few years ago.
If it was a coating defect other than sub-mm bubbles, it would be much longer than 'a few 35mm frames' (more like metres) because of the speed of the machine relative to the bead/ curtain reforming and not be a very thin straight line (Foma aren't using an ancient doctor blade dip-coater as far as I know).
I assumed that the streaks can be seen on the emulsion side of the film - but as it cannot this makes me have another idea:
If the emulsion has same thickness, it can mean that development was uneven as there are lower density areas.
What if the quality of the gelatin was not even, resulting in some of the gelatin needing more time to soak and swell during development. This then could explain why the emulsion side looks pristine, but the existence of lower density areas.
As the base moves quick through the coater, a drop of "slower-swell" gelatin is turned into a streak for the most and does result in reduced developing time.
Do you pre-soak the film?
Or maybe the silver wasn`t sensitized even - if that is possible. If some of the silver grains had lower sensitivity this also should result in lower density areas - and due to the coating speed a blob of less-sensitized silver turns into a streak.
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Or the silver grains were not evenly distributed in the gelatin. So rather a "mixing defect" than a coating defect.
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Photographic emulsion is around 10um thick. A coating defect consisting of a partially missing bit of image layer (out of several coating layers) will be all but invisible when looking at the actual emulsion side of the film, as is the case here. It's not like you get to see a hole in the layer with the base shining through or something.
A 'melted' gelatin is basically long molecules in a watery solution. Even if you take a fairly non-homogeneous gelatin and 'melt' (=dissolve) it, it'll homogenize. Non-dissolved bits (like bone, skin etc.) are exceedingly rare to encounter in even low-end technical grade gelatins, let alone food-grade or even photographic-grade gels. Even if they were to be present and somehow make it through the filtering that Foma must also use in their emulsification processes, they would show up as relatively big lumps that literally stick out of the emulsion. I don't see how an uneven swelling at this scale and of this pattern could be tracked down to a gelatin quality issue.
That's not possible. There's no 'silver' in an unprocessed film. They start with silver nitrate, which is a soluble compound, and grow insoluble crystals of AgBr, AgCl and AgI. These are inherently photosensitive. Even if they somehow managed to get the stoichiometry wrong (which would be a bit like a chef cooking a 50lb steak by accident), any free Ag+ ions would bind somewhere along the road to Cl- that's inevitably present at some stage (e.g. in the gelatin in trace amounts), and the unintended crystal distribution would not end up in very specific spots on the film, because the emulsification happens in kettles, so will be homogeneous. If the latter fails, you may see density variations from one square foot of the film to another, not from one millimeter to the next.
See above.
The size of the defect implies that whatever the cause is, it's closely associated with the coating process. A hose sucking in a tiny bit of air (venturi effect) could be an explanation, as would a partially blocked feed line to the coater causing gaps in the laminar flow from one of the slits, fouling of the coating head itself, etc. I know from Foma 200 coating defects that fouling does occur as I've encountered actual debris/particulate matter in rolls of Foma 200 120 format, so the notion that they sometimes have cleanliness problems isn't far-fetched.
Not applicable here; this strip of film was hung to dry in the same room I process all my film in. Temperature around 18C at most. Another roll of film (different brand) hung right next to it and dried fine, as do all rolls of film.
I cannot discount a drying problem at Foma's plant, but I'd be surprised that their drying lane specifically would be so inhomogeneous as to cause this kind of problem. So no, I don't think this is a likely cause at all.
Runaway dye formation would have been visible AND it's doubtful it would show up in such an isolated way; neither is present here, plus I've processed truckloads of all kinds of fomapan film in Pyrocat, as have hordes of other photographers, with no problem whatsoever. So again a far-fetched, unlikely idea.
This particular roll was affected on its entire length. The other example I posted occurred at the end of a roll and for all I know can very well extend past its end, but I don't happen to have the roll that was cut right next to it (can you imagine that). On the bulk roll I mentioned before, the coating defect started at maybe 1/3 of the roll and extended several meters and AFAIK right to the end of the roll (and likely beyond). Also, sub-mm bubbles seem like a perfectly likely cause; see earlier comment above.
It walks like a duck, quacks like a duck, so guess what - it's a coating defect, which we know for a fact Foma runs into from time to time. I don't get the endless chicaning to try and shift attention in other directions. The fact that most of the time you get film with no major problems is well known to me and many other people, but it doesn't discount the possibility of sometimes running into a problem with Foma's films, as is the case here.
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If it walks like a duck....
I have to agree that while I am very favourable towards Foma, this does look like a coating issue. I guess the only way to find out for sure would be to contact them and I understand why Koraks doesn't see the need to do so. For all the good luck I and others have had with Foma film in all it's guises, I guess there's still the odd bad batch that gets through even after they tightened QC some years ago.
Looking back I once had a 50 foot roll of 35mm Fomapan 200 which just got stuck in the bulk loader with about 1/3 left and I couldn't persuade it to unroll any further. I eventually removed it, and it seemed fine once I'd ruined it in the light. Weird but weird things occasionally happen.
I have to agree that while I am very favourable towards Foma, this does look like a coating issue. I guess the only way to find out for sure would be to contact them and I understand why Koraks doesn't see the need to do so. For all the good luck I and others have had with Foma film in all it's guises, I guess there's still the odd bad batch that gets through even after they tightened QC some years ago.
Looking back I once had a 50 foot roll of 35mm Fomapan 200 which just got stuck in the bulk loader with about 1/3 left and I couldn't persuade it to unroll any further. I eventually removed it, and it seemed fine once I'd ruined it in the light. Weird but weird things occasionally happen.
Don't get me wrong, I've shot hundreds upon hundreds of rolls and sheets of Fomapan, with great pleasure, and continue to do so. The vast majority of sheets and rolls were perfectly fine, contained no defects at all or at least none that I ever noticed. I just wanted to share this freak occurrence, which happens in my experience to be a little less of a freak in Foma's practice than when using Harman or Kodak films. Big deal; you pay considerably less and what goes around, comes around. No free lunch and all that.
On what scientific base do you say that?
Haven't you checked the transport path on the camera?
Any debris?
What the canister felt condition is?
What about the pressure plate condition?
Unless you submit the roll to Foma and wait for their reply, it's just pure speculation.
You posted here. Were people supposed to politely read your original post and say nothing? Probably everyone here has had damaged frames of film and relates your scratched photo with their own experience. Most people tend to blame something other than the manufacturer first, so you should expect some theories. And this is a discussion forum, after all, not a lecture hall.
I've had similar defects and base my speculation about iffy Foma QC based on this:
- No other film in existence has provided a variety of "fun defects" for me. Foma products have. Lines, pinholes, some "pepper grain"... Fomapan 200 and R 100 - went through numerous cassettes and Bulk rolls. R 100 in my case is the worst offender - beginning with erroneous reversal bleach times by Foma itself, ruining all my 10 films purchased directly from their webstore.
- No other film in my use has been affected by film transport and my handling of it in-camera. Transport problems would produce scratches on every fucking film and would look very well defined and with sharp edges. Alas - this defect looks completely different and other films via same camera, same gear, same projector, same handling - pristine!
- My gear doesn't touch the image area of the film whatsoever, so it's impossible for it to produce such uniform lines, crossing multiple frames at the same spot.
- I don't use squeegee - so there's really nothing at my end that could produce said streaking.
So all that remains given these facts - something's up at the production end and/or packaging - tight felt gate issues for example. But that'd make film noticeably hard to pull out, but it always have handled normally, felt normal - up to the image inspection time.
But - given the price - acceptable and it might be an action of splitting hairs to complain about this to Foma, making them investigate a freak issue - inspection costs money and time.
And I too have a low tolerance towards baseless speculation when defect is very well captured for all to see, speaking for itself. It steals energy and time to refute what's obvious.
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I stand by what I've said: without an in-depth analysis by a Foma engineer it's impossible to come to know the real cause of those scratches.
The refusal to send the offending film to Foma is incomprehensible.
It's about one's evaluation of time. And about picking one's fights.
I don't want to engage with manufacturer that offers cheapest film and has very low profit margin on their products, don't want to prepare samples and pay for shipping, waste my time on that. I want to shoot some film not pretend to be an investigator. And there's another quality cheap option - Kentmere! It produces no "fun defects" whatsoever, is very flexible, has neat latitude and its rated ISO is true.
See my arguments above - there's literally nothing at my end that could produce such lines, therefore it indicates manufacturing problems. No engineers needed to see that.
What can I say Ivo...
Since Foma hasn't give me any problem whatsoever, I will continue to use their products.
As you said, it's a matter of personal preference and evaluation of one's own time...
The negatives are my niece's holiday photos. And apart from it not being my call to make on what to do with this film, I'm not going to send them to Foma only to get confirmation of something I already know.
Also, the defects are not scratches. Scratches are sharply delineated, virtually always penetrate all image layers and are visible on the emulsion layer. None of these characteristics are the case here.
They're also not the cause of an overly tight fitting felt trap in the cassette as this would create plus density pressure marks and/or scratches (mostly the latter). Again, neither applies here.
And for the record, none of this is an attempt to take a pi$$ on the manufacturer, so anyone who is happy shooting their foma film (including me, coincidentally) and suffers from cognitive dissonance now, you can untwist your panties now. It's all cool, just an intermittent QA problem, which many people know this manufacturer sometimes struggles with.
Sorry, you have the cognitive dissonance because you seem not to understand that you can't replace a Foma engineer...
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Sheesh. Tough crowd.
As I said, it's not my film and I'm not going to bother, and I only post it here so others may use it as a point of reference. If you want to vehemently disbelieve my assessment that this is a coating defect, hey, whatever; it's a free world up there in your scalp. We've got people believing the earth is flat and that using a microwave will poison your food with radiation. I've seen weirder stuff.
But speaking of the Foma engineers. A few years ago when I ran into the well-known coating defects on Foma 200 120, I sent samples to Foma. A couple of weeks later, I got a friendly email confirming that the problem was on their side. I also received some replacement rolls in the mail a few weeks after that. Which suffered from the same defects, but hey, the gesture was nice and I appreciated the fact that they were willing to confirm what I had already figured out by a process of systematic exclusion.
So I recommended the same to a friend who had been shooting Foma 200 120 as well around the same time, who ran into the same emulsion defects. He sent his samples to Foma, and also got a polite email. The difference is that he was informed that his camera was the problem (the notorious "tight transport" excuse that several others also got around that time). Same film, same manufacturer, same problem - not the same explanation.
Even if I were to send film to Foma, how would we ever be able to make sense of the answer? They might confirm a coating defect. They might argue it's user error. We'd still be none the wiser. So what then? Send samples out to get SEM imaging done? Invoke the United Nations on the case?
Btw, here's a closer-up view of the problem, scanned at 6300dpi with a Flextight scanner, then viewed at 50% magnification:
Note the geometry of the minus-density patches, which lacks the sharp edges you'd expect of water spot damage, scratches etc. It's a very gradual. Here's a 100% crop of a representative smear:
It's literally just lower density; that's all.
Note that apart from longitudinal smears, there are also insular spots:
(25% magnificiation)
Here's what the emulsion side looks like with light shining at an angle across it:
Closer up:
Note absence of any signs of emulsion damage, scratches etc. Just pristine, clean emulsion surface. At certain angles, you can see the density variations, although they're of course quite subtle:
The insular spots imply that this cannot be a transport problem, as that would only leave longitudinal marks. Further hints are the lack of superficial damage to the emulsion and the lack of sharp definition to the features.
Moisture damage also seems unlikely due to the lack of edges to where the water droplets would have supposed to have been, and the lack of conditions that would be conducive to this damage in the first place.
Processing/development errors are ruled out by the longitudinal nature of most of the defects, which suggest a factor in which longitudinal motion plays a role, while the film was processed with manual inversion agitation. Errors during film spooling etc. are excluded by the lack of superficial damage.
Drying damage along the lines of excessive heat etc. is excluded by the lack of any change in film geometry (too hot drying conditions tend to leave visible bumps on the film) and the lack of a corresponding superficial feature on the emulsion side that coincides with the density anomalies.
Pressure mark damage due to cassette assembly problems are ruled out by the lack of pressure marks (which result in plus-density anomalies, not minus-density) and the absence of any signs of scratching of the emulsion or backside of the film.
The likely explanation of the marks is a relatively lower silver halide density in the affected areas. Since nothing has physically removed anything from the emulsion prior to film processing, and processing itself being excluded due to reasons mentioned above, the only logical explanation is that the silver was never deposited in the first place. I.e., a manufacturing defect.
Note the geometry of the minus-density patches, which lacks the sharp edges you'd expect of water spot damage, scratches etc. It's a very gradual. Here's a 100% crop of a representative smear:
It's literally just lower density; that's all.
Note that apart from longitudinal smears, there are also insular spots:
(25% magnificiation)
Here's what the emulsion side looks like with light shining at an angle across it:
Closer up:
Note absence of any signs of emulsion damage, scratches etc. Just pristine, clean emulsion surface. At certain angles, you can see the density variations, although they're of course quite subtle:
The insular spots imply that this cannot be a transport problem, as that would only leave longitudinal marks. Further hints are the lack of superficial damage to the emulsion and the lack of sharp definition to the features.
Moisture damage also seems unlikely due to the lack of edges to where the water droplets would have supposed to have been, and the lack of conditions that would be conducive to this damage in the first place.
Processing/development errors are ruled out by the longitudinal nature of most of the defects, which suggest a factor in which longitudinal motion plays a role, while the film was processed with manual inversion agitation. Errors during film spooling etc. are excluded by the lack of superficial damage.
Drying damage along the lines of excessive heat etc. is excluded by the lack of any change in film geometry (too hot drying conditions tend to leave visible bumps on the film) and the lack of a corresponding superficial feature on the emulsion side that coincides with the density anomalies.
Pressure mark damage due to cassette assembly problems are ruled out by the lack of pressure marks (which result in plus-density anomalies, not minus-density) and the absence of any signs of scratching of the emulsion or backside of the film.
The likely explanation of the marks is a relatively lower silver halide density in the affected areas. Since nothing has physically removed anything from the emulsion prior to film processing, and processing itself being excluded due to reasons mentioned above, the only logical explanation is that the silver was never deposited in the first place. I.e., a manufacturing defect.
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Very similar experiences here: Foma has been mostly very honest and humble in their behaviour and concerning assessments of their products. They have been always present at Photokina in Cologne, which has been the biggest and most important photo fair in the world before they cancelled it in the pandemic.
At the talks on their booth at Photokina they have been very honest and open minded, explaining that
- they don't operate at the same technology level as Kodak, Fujifilm, Harman
- their films are therefore more simple, single-layer coatings
- they want to offer significant lower prices than the big companies
- they see these "budget products" for beginners, students, budget restricted photographers, lower-income markets (emerging markets) as their target markets and "market niches"
- they cannot and don't want to compete with the premium / highest quality products like T-Max and Delta films, Acros or Ilford's Multigrade V papers.
By the way, that strategy seems to be very successful for Foma: Due to two of my reatil sources Foma is meanwhile number two in BW sales behind Harman / Ilford Photo, and Kodak has fallen behind on rank three with a big distance.
Have 'they' told you this? Odd.
If true, there seems to be a certain disconnect between them and their real customer base then, because their market includes also loads of non-budget restricted photographers in higher-income markets who use their products because it has certain rendering qualities, regardless of price. Are you German, Niko? If you're on facebook, take a look at what Dirk Hampel often shows in the German film photography groups, using Foma's medium format film range and some Hasselblad kit. His work blows away stuff many 'pros' do with Tmax.
These customers, Niko, will keep buying Foma in batches of tens or hundreds of rolls per month even if it costs 70% more, provided QC is improved and they don't have to throw away entire batches. However if QC keeps being problematic and Foma doesn't act, they will eventually move away.
As for the beginners & budget restricted - it sounds like a really odd business strategy that of selling quirky, temperamental, sometimes flawed (though often beautiful) film to beginners. Imagine a beginner or a budget-restricted stumbling on the flaws shown above and torturing themselves because it's unclear where the issue lies. They might give up the hobby altogether and go back to digital. Shame. As much as I love Foma film, I personally would never recommend Foma products to beginners. They take a lot of fine tuning to really see what they're capable of. I would recommend them to seasoned professionals who want a 'different brush'.
I think - personally - Foma needs to review their entire product line, iron out the issues, fix Foma 200 in 120 once and for all (I miss it so much!) and pass the mark up on to the customers.
Coating faults would generally be pretty sharp edged - like pinholes and streaks or a comet and a tail - and it does not look like poor melt mixing (or just a plain poor melt - I have some Efke from the end of Fotokemika's manufacturing era that very clearly shows their plant was on its last legs) or surfactant issues (the bands would be considerably wider and clearly defined - and I think you'd generally see major coating issues in physical relief - the supercoat would 'fall' into the holes, especially if it is coated purely as a single emulsion layer (maybe - going over ISO 200 with conventional 3D crystal emulsions seems to cause a major rise in emulsion turbidity etc - as opposed to controlled crystal growth epitaxial ones like Ilford Delta) + supercoat).
Foma films are less heavily hardened than others, the 400 has a thicker emulsion - this adds together to make it much more susceptible to stress marking anywhere from post-coating roll-up, to slitting, to any of the many stages involved in confectioning, especially if the hardener takes a few weeks to hit maximum durability - and if the roll was slit early, that could be a cause. Another aspect of this may be developer related - in some circumstances (cf. the 220 Shanghai thread) some developers seem to strongly intensify any manufacturing stress marks - where mainstream ones (used for manufacturing QC) don't - that was why I mentioned Pyrocat - it has been known to cause strange and atypical faults with Foma emulsions.
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I understand about the other points, but i still have ideas about the gelatin:
Yes, the emulsion is very thin - and i don`t think of holes the layer - but if the emulsion on the lower density areas was a bit thinner than the rest, it still may be visible to the eye.
A vinyl record, with microgroove, does contain groove modulations being down to 1um (some say its even smaller) - and that`s why a microgroove does shine in rainbow-colors if the light is hitting it at a certain angle.
If now the emulsion of the film was not even in height but had small sags, just one or two um, these still could be visible by reflecting the light in a different color - like the small modulations of a microgroove.
Also if no effect can be seen on the developed emulsion, maybe a different effect could occur - elastic deformation. Some part of the manufacturing machine - or photocamera - may have compressed the gelatin to some extend, so when developing started this part of the emulsion took longer to soak developer and therefore did produce lower density areas.
By soaking developer the elastic deformation was canceled, leaving no visible streaks on the developed negative.
I am that focused on the gelatin because you mentioned at the beginning that you have not found (a lot of ) others to have this kind of effect on their film. Because if you did pre-soak the film, compressed gelatin could reform, properly soak developer and by that from even density.
If other users pre-soak their Fomas, they may not run into problems like these.
@Lachlan Young I have no way to determine from my perspective at what stage in manufacturing (up to and including confectioning) the defect must have been caused. I also understand that choice of developer may have a slight impact on how strongly it manifests itself, although that would be a contributing factor of lesser relevance. Similarly, if the entire roll would have been filled with low-key scenes of shrubs or something else with lots of fuzzy texture, the defect wouldn't have shown up. The fact though is that the defect is there, and that no other logical explanation fits the symptoms than a manufacturing-related fault.
I really can't see a 3um thickness difference - it's on this order of magnitude we're talking. You'd be able to see if it it was sharply featured, but as you can see, this isn't. In practice, you really can't see the kind of small valley that we're talking about here. If I use my imagination and hold the emulsion to the light in just the right angle, I think I miiiiiighht just see a variation in the surface, dipping slightly where the stripes are, but really, it might just as well be the effect of the optical density just as well. I've tried to capture it on the shots I've shown above and as you can see, it's basically invisible.
It would either have had to deform the base along with the emulsion, which would show up as a very nasty set of bumps along the whole length of the roll, or the emulsion would have had to locally spall off the base to accommodate for the dimensional changes. Neither is evidently the case. I'm sorry, I don't see much merit to the hypothesis of a deformation that was there at the start of development and then magically disappeared. It doesn't make sense from a physical or a chemical perspective. And once more - pressure marks tend to result in plus density. You try it yourself; take an unexposed bit of film (in the dark) and scratch your nail across the surface. Works with paper, too. Then develop it. You'll get density. Only if you scratch hard enough to physically remove the emulsion, you can get minus density this way - but that also leaves physical density.
Fact is that I don't know what aspect of the manufacturing process caused this, only that it must have happened before the film was ever loaded into the camera, and that no other factor related to logistics, storage, xrays etc. etc. fits the damage pattern.
Problems like these are often intermittent; you get a bad patch on a master roll and that bad patch distributes across a number of confectioned rolls. They then get spread out over the world if the QA department doesn't catch them. I happened to get this particular roll of film in my hands; I bet many of the other affected rolls from the same batch ended up in potentially infinite storage, were happily embraced by a crowd thrilled with these 'vintage artefacts', led to some photographers cursing the lab they used believing it was their fault, and yet some more may have been processed by novice darkroom workers assuming they must have done something wrong and decide to keep an extra close eye on developer temperature next time (or do a magic rain dance or whatever), etc. Most the problem it is likely unnoticed, ignored or misinterpreted - and even if it's noticed and properly identified, not much of it will be documented in a publicly accessible place. That's all I wanted to do really; put it out there. Given that they're not my negatives and the film was purchased some 2 years ago, I don't see much sense in bugging Foma about it now; what good does it do them to know they had a QA issue 2-2.5 years ago? I bet they have them every week and they probably catch the vast majority of them.
I really can't see a 3um thickness difference - it's on this order of magnitude we're talking. You'd be able to see if it it was sharply featured, but as you can see, this isn't. In practice, you really can't see the kind of small valley that we're talking about here. If I use my imagination and hold the emulsion to the light in just the right angle, I think I miiiiiighht just see a variation in the surface, dipping slightly where the stripes are, but really, it might just as well be the effect of the optical density just as well. I've tried to capture it on the shots I've shown above and as you can see, it's basically invisible.
It would either have had to deform the base along with the emulsion, which would show up as a very nasty set of bumps along the whole length of the roll, or the emulsion would have had to locally spall off the base to accommodate for the dimensional changes. Neither is evidently the case. I'm sorry, I don't see much merit to the hypothesis of a deformation that was there at the start of development and then magically disappeared. It doesn't make sense from a physical or a chemical perspective. And once more - pressure marks tend to result in plus density. You try it yourself; take an unexposed bit of film (in the dark) and scratch your nail across the surface. Works with paper, too. Then develop it. You'll get density. Only if you scratch hard enough to physically remove the emulsion, you can get minus density this way - but that also leaves physical density.
Fact is that I don't know what aspect of the manufacturing process caused this, only that it must have happened before the film was ever loaded into the camera, and that no other factor related to logistics, storage, xrays etc. etc. fits the damage pattern.
Problems like these are often intermittent; you get a bad patch on a master roll and that bad patch distributes across a number of confectioned rolls. They then get spread out over the world if the QA department doesn't catch them. I happened to get this particular roll of film in my hands; I bet many of the other affected rolls from the same batch ended up in potentially infinite storage, were happily embraced by a crowd thrilled with these 'vintage artefacts', led to some photographers cursing the lab they used believing it was their fault, and yet some more may have been processed by novice darkroom workers assuming they must have done something wrong and decide to keep an extra close eye on developer temperature next time (or do a magic rain dance or whatever), etc. Most the problem it is likely unnoticed, ignored or misinterpreted - and even if it's noticed and properly identified, not much of it will be documented in a publicly accessible place. That's all I wanted to do really; put it out there. Given that they're not my negatives and the film was purchased some 2 years ago, I don't see much sense in bugging Foma about it now; what good does it do them to know they had a QA issue 2-2.5 years ago? I bet they have them every week and they probably catch the vast majority of them.
Of course you cannot see 3um with the naked eye - i but it may be possible to observe the diffraction (? not sure about the term right now) a 3um groove can create to light-color, like the groove of a vinyl record.
I am aware of pressure-exposure and i don`t consider this to be the case here - as it would increase density on the negative. No, i am thinking of a compression of the emulsion which was present till development.
Not a bad compression, no peel off of the emulsion, just a slight compression. Not every emulsion is prone to pressure-exposure to the same extend. A slight compression not producing pressure-exposure should be possible.
I was thinking of this memory-effect. There are spoons you can bend like mad, but if you put them into a cup of hot coffee, they will spring back to ordinary spoon-form. What's the name of this effect again... memory-deformation... elastic-memory-deformation... i cannot recall right now.
With gelatin i can imagine the same to be possible:
You compress it slightly by a few um - without producing pressure-exposure - the gelatin will remain compressed at this spot, but will soak with developer and swell (respectively dry) back to an even surface.
But because the compressed part took longer to soak developer, lower density formed.
I also don`t see sense in contacting Foma, unless you have to know what (manufacturing-)problem caused this effect.
It`s just a theory anyway.
Btw, can a developer dissolve fats?
Btw, can a developer dissolve fats?
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