Getting more rolls out of C-41 chemistry / aka. Have you tried the Adox/Tetenal/Rollei/Bellini C-41 kit?

There are many C-41 development kits, but their capacity claims follow a consistent pattern:

• Kodak: 8 rolls of 135 / Liter.
• Arista: 8 rolls of 135 / Liter + a note that you might get more but YMMV.
• Unicolor: 8 rolls of 135 / Liter + a note that you might get more but YMMV.
• Bellini: 12 Rolls of 135 / Liter + progressively longer dev times after the 3rd roll.
• Adox: 16 Rolls of 135 / Liter + progressively longer dev times after the 4th roll.
• Rollei: 16 Rolls of 135 / Liter + progressively longer dev times after the 4th roll.
• Tenetal: Defunct, but reborn as Adox.

C-41 his highly standardized, and a look at the MSDS of these kits shows how similar they are. Of course they all use CD4, and other ingredients vary in ways that look entirely equivalent (as you'd expect).

Clearly, there is nothing special about Bellini/Adox/Rollei/Tenetal chemistry. They just made a different guess than PSI (who makes Kodak/Arista/Unicolor) about how people will use the kits and/or how much color shift users will tolerate. For reference, here are the times for 1 L of developer:

(Edit: Fixed the table formatting)

.	3 min 15 s	3 min 30 s	3 min 45 s	4 min
Kodak	Rolls 1-8	.	.	.
Arista/Unicolor	.	Rolls 1-8	.	.
Bellini	Rolls 1-3	Rolls 4-6	Rolls 7-9	Rolls 10-12
Adox/Tenetal/Rollei	Rolls 1-4	Rolls 5-8	Rolls 9-12	Rolls 13-16

Note: This is for rolls of 36 exp 135 film, or 120 film. All developed at 38°C.

My Question: Have you tried any of the kits that say to process more rolls by extending the dev time? How did it go? How do you feel about the color shift?

All C-41 developer has same capacity, some companies state that you can increase the number of rolls per unit if you are willing to accept degradation in quality.

One other thing you're going to really need to extend Blix times as the fixer portion is really going to be exhausted.

The first rolls & sheets of C41 film I processed myself, I ran through a liter of Rollei chemistry. I stretched that liter until things started to look really iffy even to my untrained eye. In hindsight, I had blown over half the film I had processed to smithereens by doing so. Some of those negatives were in principle exposed just fine, but cannot be printed. At the time, I felt they scanned just fine (I now disagree with myself on that, too), so I thought everything was going great and capacity numbers were grossly understated.

The gist of the story is that the failure is a creeping one. You'll only realize it when it's far too late.

dcy said:

My Question: Have you tried any of the kits that say to process more rolls by extending the dev time? How did it go? How do you feel about the color shift?

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I'm pretty sure I've always used kits that stated to extend the dev time and blix time.

Most recently (last couple of years) Tetenal and Ilford - before that was Agfa.

I haven't noticed any colour shifts that can't be attributed simply to shooting fixed colour balance film in varying light conditions without CC filters in front of the lens when required.
I always stick to the box instructions and toss after 16 rolls per litre and always at C41 process temperature.

dcy said:

My Question: Have you tried any of the kits that say to process more rolls by extending the dev time? How did it go? How do you feel about the color shift?

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There was already a similar topic here on the forum and you even participated in it.

Two months ago, I argued that, regardless of the kit manufacturer's claims, you shouldn't exceed 8-10 rolls of film per liter of developer and use the developer within 7-10 days.
Now, after two months, I believe the maximum number of rolls shouldn't exceed 8 (really, not a single roll more!).
There's no point in skimping on chemicals if you want consistent results. Of course, many of us scan film and process it digitally. Also, many of us like different kinds of color shifts because they feel the artistic spirit.

Exactly as @koraks wrote, excessively extending the amount of developed film per liter, even with the development time correction, will have consequences not only in the form of color shifts but also underdevelopment in shadows, sometimes increased grain, etc.
Even if you scan your film, do not skimp on chemicals.
You'll realize this when it's too late.

Spektrum said:

There was already a similar topic here on the forum and you even participated in it.

Kodak Gold 200 & Adox C41 kit - help with troubleshooting heavy colour casts

Just another note to add that I've further refined my development workflow with the ADOX C41 kit by controlling temperature even earlier, at the pre-soak stage. I'm now doing a longer pre-soak, using 1L of water kept in the sous vide bath running at 39 Celsius. Sampling the temperature of the...

www.photrio.com

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Depends on what one means by "similar". Looking back at that thread:

(1) The discussion I that thread was not about whether increasing the dev time is a good way to get more rolls out of a kit.

(2) My entry into the conversation was to about blix.

I do not remember whether I read your comment about how many rolls you can get out of a kit. But if I did read it, I do not think I would have necessarily made the connection to my question here about increasing the development time.

Spektrum said:

Exactly as @koraks wrote, excessively extending the amount of developed film per liter, even with the development time correction, will have consequences not only in the form of color shifts but also underdevelopment in shadows, sometimes increased grain, etc.
Even if you scan your film, do not skimp on chemicals.
You'll realize this when it's too late.

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My take-away from @koraks ' comment and the one from @gbroadbridge was that trying to eye-ball the color is a recipe for failure, and I should instead pick a number of rolls I will process with each liter and stick to it, even if a color shift is not apparent.

Agreed with Koraks. I used to do 30 films in a 1 liter C-41 kit. Then I realized I was pushing it and did 20. Now, I'd probably do about 15 or 16 at the max.

When you calculate the cost of chemicals per roll of film and make that into a percentage of your total photography cost, it's small and doesn't make sense to skimp. Years ago when it was easy to find film for $1 or $2 a roll, it might have been okay for someone learning and taking their "worst first 10,000" pictures.

The biggest chalenge is that it is very difficult to judge a color negative film. C-41 chemistry is always going to deliver something, even when you pass the acceptable thereshold, but most probably you are not going to notice it on the film.

The instructions for reuse only makes some sense if you are doing manual inversions, for rotary processing things are not so clear. With 1 liter I can process in my Jobo up to eigth 35 mm or ten 120 rolls, way above the limit of 3-4 rolls per batch described. In the case of 120 format (my usual case), the advantage of reusing Bellini chemistry is very little (12 Vs 10 rolls). With Adox/Tetenal I can process substancially more rolls (16 Vs 10) but demanding much more time to develop (four batches instead of one). Same thing happens with 600 ml (six 120 rolls) or 250 ml (two 120 rolls). End of the story: I don't reuse with rotary processing. I buy minilab chemistry instead, that can be much more cheaper than amateur kits, and my current development cost is around €1 per roll.

loccdor said:

Agreed with Koraks. I used to do 30 films in a 1 liter C-41 kit. Then I realized I was pushing it and did 20. Now, I'd probably do about 15 or 16 at the max.

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Thanks! That 15-16 / L is still a lot more than the mere 8 recommended by Kodak, and closer to the Adox/Rollei recommendation.

loccdor said:

When you calculate the cost of chemicals per roll of film and make that into a percentage of your total photography cost, it's small and doesn't make sense to skimp...

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So far I have been shipping my film to a lab, which costs as much as the film. I recently ordered the Kodak 2.5 L kit. If I process 8 rolls / L, that will cut my development cost my more than half, but it'll still be 42% of the price of Kodak Gold. If I can reach your 15-16 rolls / L max, or just 12 rolls / L but switch to Kodak's 5 L kit, my development cost would become 21% the cost of the film. I think that is a good target to aspire to.