Identifying film coating faults vs. handling / process problems.

[Tim V]

Hi all,

I'm wondering if there is any online resource here or elsewhere with pictures on how to determine if a fault seen in a processed sheet of film is a coating vs. a processing fault.

I ask this because I've been trialling a new brand of film and am seeing things I've never seen with Ilford or Kodak. Some things like pinholes, but also things that look like scratches in the emulsion – I'm fastidious and in over 1000 sheets of 8x10" film I've never seen it quite like this before – and things I might describe as pitting, plus subtle – but visible at certain print densities – banding in the skies.

I process in a Jobo using an expert drum, if that makes a difference.

Thanks,

Tim

[Bob Salomon]

Have you contacted the film maker? If there is a problem they can’t fix it without hearing about it. But if film coating was a problem there would be hundreds, if not thousands, of users contacting them.

[Sal Santamaura]

My late grandfather once shared the wisdom with me that "you're not wealthy enough to afford cheap stuff." :)

Why struggle with such issues when Kodak and HARMAN still offer top quality products?

[Pere Casals]

Hi all,

I'm wondering if there is any online resource here or elsewhere with pictures on how to determine if a fault seen in a processed sheet of film is a coating vs. a processing fault.

I ask this because I've been trialling a new brand of film and am seeing things I've never seen with Ilford or Kodak. Some things like pinholes, but also things that look like scratches in the emulsion – I'm fastidious and in over 1000 sheets of 8x10" film I've never seen it quite like this before – and things I might describe as pitting, plus subtle – but visible at certain print densities – banding in the skies.

I process in a Jobo using an expert drum, if that makes a difference.

Thanks,

Tim


You may provide detailed information: film, developer, stop bath type and high res crops of the pitfall.

¿do you make a final rinse with distilled water? ¿filter? ¿have water borne particles?


One possible cause for pins are carbonic bubbles generated when some films soaked with some developers are placed into an acid stop bath... carbonate reacts making carbonic bubbles inside emulsion.

Try distilled water for final rinse, and try plain water stop bath, if problem continues post hires crops of the pins.


It can also be air bubbles in developer/film, See here (http://www.afterness.com/darkroom/film_developing_problems.html) the "pinholes" link. Tap water may contain air that is released when water losses pressure...

[jp]

You may need to sacrifice a few sheets to examine in daylight fresh out of the box.
Once I had had some scratched up 8x10 fresh out the box, not from one of the major two manufacturers. I stopped using it.

Other people have had great film but processing decisions cause pinholes, etc...
Subtle banding could very likely be developing choices.

[Sal Santamaura]

...Subtle banding could very likely be developing choices.Or, more likely, standing waves in the emulsion during coating by the manufacturer.

[Drew Wiley]

It's extremely unlikely that either of these two major manufacturers would have the same problem. It's probably related to your drum technique.

[Bob Salomon]

It's extremely unlikely that either of these two major manufacturers would have the same problem. It's probably related to your drum technique.

He hasn’t specified which manufacturer’s film he used.

[Drew Wiley]

Thanks Bob. I re-read it, and it seems you're right. I have had the problem he describes with Forte/Arista 200 sheets, even tray developed. But that's the only case.

[Tim V]

I purposely didn’t name the manufacturer because I want to know what I’m seeing first on my negatives before pointing the finger. I will say that it’s not from one of the big two though. As I said also, I’ve never seen these things with Ilford but that’s not to say it’s not my developer or something.

Any resources to reference? I’ll post samples soon...

[Tim V]

PS: I’m using PMK in the Jobo with the Bergger Roto Additive. Water stop and rinse. Ilford Hypam fix. Water is filtered to extremely fine grade. Rinse is in filtered water.

My guess for banding is that it would be extremely unlikely to be the drum I’m using as the bands seem the same on all sheets - if I lined them up they’d continue through at exact spacing and height. They’re very faint, but visible if I print dark.

[Pere Casals]

I purposely didn’t name the manufacturer because I want to know what I’m seeing first on my negatives before pointing the finger.

You don't point the finger. You say you have a problem with a particular film/processing, if you provide data (the crops) others may help you if they had the same.



Any resources to reference?

This pdf is about pitfalls in processing, not in emulsion defects, it's about technical imaging (NDT), but it solved me some problems I had:

ndt-ImageGuide-201403.pdf

search that doc with google

[Tim V]

Thanks Pere, I'll check it out!

I'll post some crops when back at the studio, hopefully tomorrow.

[Sal Santamaura]

...Any resources to reference? I’ll post samples soon...Ask your question and post those samples at PHOTRIO. Direct them specifically to Ron Mowery ("Photo Engineer"). He's retired from Kodak Research Lab, spent many years working on coating of various films and will provide authoritative information when answering. He's done so before.

[Tim V]

After analysis of the scans and negatives under the loop I can say that it’s simply badly scratched emulation, but not due in any way to processing or my handling - I’m simply far too careful and in a great quantity of other brand film processed in exactly the same way I’ve never seen scratches like this before - maybe the odd scratch, but I’m talking quite intense, localised areas of scratching in many areas of same negative. Too bad, I like the tonality if the film.

Like many others have already said, perhaps my experiment simply tells me that it’s not worth straying from “the big two”...

[Pere Casals]

but not due in any way to processing or my handling - I’m simply far too careful and in a great quantity of other brand film processed in exactly the same way I’ve never seen scratches like this before

You cannot be sure about that... Perhaps your processing has been careful enough for (say) TMX/D100, but for example if your fim is (perhaps rebranded) beautiful Shanghai GP3 then you may consider using a hardener and you should not touch the emulsion when wet, using Film Squeeze may destroy some (old tech) films. I've not used GP3 recently, but it was really easy to scratch.

I never had a problem with ilford/kodak but for GP3 I had to change my procedures, it consisted in using a final distilled water rinse to not have to squeeze much the film.

...so you may do that, don't squeeze a test sheet, if scratches disapear then buy some Double-Distilled (bidistilled) water and make a final rinse with it, you may reuse the bidistilled bath, but in that case do it like with double fixing bath, have separated first and a second baths, and after some 30 reuses dump the first bath use the second bath as first bath, and refill the second bath with bidistilled. If using photoflo then use only a fraction of the normal dose.

Reusage of Bidistilled may be cost effective, because it's more expensive.

[Tim V]

Apologies, I forgot to say I inspected an unexposed sheet in the light. I could see subtle marks on it.

I guess I was just really hoping it was a handling fault because the film is really nice, save for these issues which apart from the subtle banding seem random but frequent enough to be too risky in my book.

I’m not keen on naming the manufacturer as it’s possible I’ve simply been unlucky and in any event I’ll raise it with them directly - in my experience that is a more positive way to do it and will more likely lead to product improvement.

[Bob Salomon]

Apologies, I forgot to say I inspected an unexposed sheet in the light. I could see subtle marks on it.

I guess I was just really hoping it was a handling fault because the film is really nice, save for these issues which apart from the subtle banding seem random but frequent enough to be too risky in my book.

I’m not keen on naming the manufacturer as it’s possible I’ve simply been unlucky and in any event I’ll raise it with them directly - in my experience that is a more positive way to do it and will more likely lead to product improvement.

No, what you are really saying is that if it is a film problem, you will let unsuspecting browsers here run into the same problem since they won’t know what you found!

[jp]

PMK can streak under some conditions, so that sky/highlight unevenness could be tested with another developer. But if you're finding damage to the film prior to it going into film holders, time to stop using it.