Can you help with this ? "crackles" or "marble" on 16mm Fomapan R 100

[chris67]

Hello, this is my very first post, I hope everything will be ok !
I'm collecting old movie cameras, and I'm experimenting a way to cheaply test them all.
So I developed small portions of 16mm Fomapan R 100, here are the details :
(I am beginning with a 1938 Kodak Eight movie camera , exposing 1/30sec f8.)
all liquid temp is 16°C
- bleach with hydrogen peroxyde 12%, and citric acid 20g per liter, 20mn
- washing 5 mn, developing with HC110 B solution, 20mn
- fixing for 5mn, washing 5mn.
The result is a slightly yellowed negative, slightly under developed (or under exposed ?)
My problem is the "marble", or "crackles" that is appearing, I really don't know where it is coming from.
Maybe you can help ?
Thanks a lot !

 

[chris67]

View attachment 307174

 

[Europan]

Too little agitation, probably in every bath. Bleaching acts concentrated in spots.

Change to a workflow in the dark with open tubs wherein you can move your spiral around. You will be able to cut bath times by 50 percent. I have processed motion-picture films of all sorts professionally and commercially for many years. Best practice I happily share with everybody. Bath temperature should be 20 degrees Celsius minimum.

 

[Europan]

Réticulation de la couche photographique. Tu développes trop longuement. Bien agiter, raccourcir le temps dans un bain

 

[MattKing]

Two threads combined into one.

 

[chris67]

Thanks a lot for your anwer ! You must be right, I had very little agitation during all the baths, because when developing regular 24x36 films I am agiting once every 30 seconds. I have no spirals, as I designed my own very tiny developing tank, see the picture. What do you think of the process I'm using, is the timing correct ? Thank you again.

 

[chris67]

Two threads combined into one.

Yes, I am very sorry, I could not figure how to delete the first thread.

 

[MattKing]

Yes, I am very sorry, I could not figure how to delete the first thread.

That is okay. Welcome to Photrio, and I hope that you find what you need, and are interested in participating here.

 

[chris67]

Réticulation de la couche photographique. Tu développes trop longuement. Bien agiter, raccourcir le temps dans un bain

J'ai vu dans les forums que le fomapan reversible doit être développé plus longtemps, d'ou mon temps de 20mn. Mais c'est déja un peu sousex, si je reduis le temps de moitié par exemple, je risque une sousexposition encore pire, non ?

 

[AgX]

My problem is the "marble", or "crackles" that is appearing, I really don't know where it is coming from.

View attachment 307174

That structure is called "reticulation", it is due to extreme shrinking and then rupturing of the emulsion.
It is nowadays lesser seen than in the past.

It is typically due to strong temperature changes during processing. But strong ph changes may be of influence too.

Foma emulsions are known to be of lesser strength.

 

[AgX]

I'm collecting old movie cameras, and I'm experimenting a way to cheaply test them all.

So I developed small portions of 16mm Fomapan R 100, here are the details :
(I am beginning with a 1938 Kodak Eight movie camera , exposing 1/30sec f8.)
all liquid temp is 16°C
- bleach with hydrogen peroxyde 12%, and citric acid 20g per liter, 20mn
- washing 5 mn, developing with HC110 B solution, 20mn
- fixing for 5mn, washing 5mn.

For just testing them a standard processing to a negative shoukd be sufficient, I assume.

 

[chris67]

That structure is called "reticulation", it is due to extreme shrinking and then rupturing of the emulsion.
It is nowadays lesser seen than in the past.

It is typically due to strong temperature changes during processing. But strong ph changes may be of influence too.

Foma emulsions are known to be of lesser strength.

Thank you AgX for your reply. Yes I was rather light about testing the temperature. I will do my best and do some testing again with more accurate temp measuring, thank you again.

For just testing them a standard processing to a negative shoukd be sufficient, I assume.

Well, due to the anti-halo layer part of the reversal Fomopan, I have read that the result will be very very dark, and unable to scan, that's why I bleached first to remove the antihalo layer.

 

[flavio81]

For just testing them a standard processing to a negative shoukd be sufficient, I assume.

Fomapan R100 can't be developed as a negative.

 

[Bronson Dugnutt]

Foma's R100 stocks are relatively more durable when compared to the Fomapan variants, but still isn't immune to emulsion softening & reticulation, even when using Foma's official permanganate-based reversal kit.

If you haven't already, search these forums for 'peroxide bleach' and you can find examples of others using the same or similar formula for B&W reversal and the challenges they encountered.

Indeed, the silver based anti-halation layer makes direct development to a negative produce less-than-ideal results.

 

[AgX]

Well, due to the anti-halo layer part of the reversal Fomopan, I have read that the result will be very very dark, and unable to scan, that's why I bleached first to remove the antihalo layer.

Fomapan R100 can't be developed as a negative.

I overlooked this fact.

However for testing the mechanics of a camera (frame steadiness etc.) it should still work from what Bronson just showed.

(Well, it was just about saving hassle, sooner or later at full-length processing the reversal process has to be handled anyway...)

 

[chris67]

Foma's R100 stocks are relatively more durable when compared to the Fomapan variants, but still isn't immune to emulsion softening & reticulation, even when using Foma's official permanganate-based reversal kit.

If you haven't already, search these forums for 'peroxide bleach' and you can find examples of others using the same or similar formula for B&W reversal and the challenges they encountered.

Indeed, the silver based anti-halation layer makes direct development to a negative produce less-than-ideal results.

View attachment 307180

Thank you Bronson for your informationand your picture, it is very useful.

 

[Europan]

Buy yourself a proper spiral reel and some plastic tubs. Fomapan R 100 can be processed within an hour, dry to dry.

 

[AgX]

Well, I find that tank not uninteresting...


A tiny tank for test-processing a short film strip in a less than normal bath-volume. Maybe heightened for 35mm.

Worth a thread on its own.

 

[chris67]

Well, I find that tank not uninteresting...


A tiny tank for test-processing a short film strip in a less than normal bath-volume. Maybe heightened for 35mm.

Worth a thread on its own.

Thank you ! I designed it to develop a 10cm slice from a 2x8mm film reel, it only takes 50 ml of liquid to develop a film. It is very lightproof, and waterproof, but not designed to reverse tank.

 

[AgX]

Well, you could redesign the funnel so that it takes a lab rubber-stop. Or give it a thread to accept a beverage or lab screw-on cap.

 

[chris67]

Well, you could redesign the funnel so that it takes a lab rubber-stop. Or give it a thread to accept a beverage or lab screw-on cap.

Yes sure !

 

[AgX]

It might be an outcome for experimenting with rare or expensive processing baths.

BUT there is a commercial alternative: use a 1x 35mm tank (in your case with a 16mm reel and just push-in a 10cm strip, rotate instead of invert and use the minimal volume to wet that strip.

 

[snusmumriken]

It is reticulation, but as AgX says it generally results from sudden temperature changes. I have never before heard it suggested that it has anything to do with agitation. pH shock sounds plausible though.

Very cold wash water has caused it for me in the past. I avoid it by keeping a bucket of water at room temperature. I fill the tank with this after the fixer, then gradually displace it using tap water through a hose fed to the bottom of the tank. This minimises any temperature shock.

 

[Sirius Glass]

Reticulation as others mentioned can cause the crackling problem. Keep the chemical temperatures the same or close to the same temperature. Sitting the bottles in a water tub to stabilize the temperature may help.

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