Questions about C41 chemistry and process

[Mikey Antonakakis]

Not sure if I should start a new thread, I’d be happy to if this is too off-topic or too old of a thread. I’m looking to clarify a few small details before I start using the Fuji Hunt C41 kit with Jobo CPE2 with Lift.

Question 1, age of kit:
Purchased almost 2 years ago and didn’t open the box until today, stored at 20C the entire time - developer Part C is still a pale clear yellow-ish color so I assume it’s safe to use?

Question 2, mixing and storage of C41 kit:
I plan to use the kit to make 500mL of working solution at a time, breaking up the Developer Part C into individual 10mL glass bottles topped with argon until used to mix new working solution. All other unused chemicals I will plan to store in their original bottles topped with argon. Working solutions will be made with distilled water (from grocery store) and will be stored in amber glass bottles topped with argon, transferred to the Jobo bottles when using, then back to glass/argon when stored. Any issues I am overlooking here, or any further suggestions?

Questions 3+, about process details:
Fuji kit instructions mention doing a preheat - it’s not clear to me if I should do that as a pre-wash? Or just leave the dry/empty drum spinning in contact with the bath water?

Between process steps when using the lift, I’m a little uncertain about timing:

• Do I start timer as soon as the first of the developer hits the film, or once I finish pouring and all of it hits the film?
• Instructions with the kit mention “includes 10 seconds drain time” - do I begin the lift at the moment the 3:15 timer goes off, or do I look to finish expelling all the developer when the 3:15 timer goes off?
• Should I leave the lift up for some time and bump it a few times at the top of the stroke to try to get the last drops of developer down the tubes? Or immediately drop it when developer stops flowing from the discharge tube?

Question 4, to stop or not to stop?:
I know C41 doesn’t specify use of a stop bath, but to get better control of development timing and/or to minimize contamination of the bleach (at least in part due to any remaining developer in the discharge tube), should I use a stop before bleach? Or just pour the bleach straight in? If I stop any recommendation for chemical, or just use water?

Question 5, rinses:
Our tap water is relatively hard, but I have a filter on my temperature-controlled faucet, any issue with using it for the rinse cycles? (I plan to rinse in the CPE2 to help clear the discharge tubing).

Question 6, stabilizer:
I plan to remove film from reels and use a separate tank for stabilizer. I assume using distilled water, one-shot, would be best? Then just hang to dry, or use squeegie? (Would prefer not to squeegie to avoid scratches). I also have a large air compressor and could blow most of the water off…

Question 7, temperature:
I plan to use both the built-in heater and a CineStill sous vide device to heat and circulate the bath water (with jobo temp set a couple degrees lower than the sous vide). I will use my temperature-controlled filtered water tap to fill the bath at roughly 38C to save heating-up time. Also plan to use a digital thermometer as the final say on bath water temperature. I am thinking it would be a good idea to use water to simulate developer temperature loss during the pour process, to calibrate water bath temperature to in-tank temperature. I would probe the tank with a thermometer at the start and finish of a simulated development cycle, and adjust bath temperature to get in-tank average temp as close to 37.8C as possible?

Question 8, bleach and fix times:
As these processes go to completion, I assume there’s no negative impact of running them for a little extra time, especially towards the end of life of 500mL working solution?

Question 9, number of rolls before mixing new batch of chemicals:
Considering I’ll be using ~250mL of the 500mL working solution, and for the time being running either one 120 roll or two 36exp 35mm rolls at time (1520 tank), any reasonable guidelines for total number of rolls of 400 speed film before I make a new batch of working solution? Should I extend times per the Fuji instructions? (I know the proper answer would be “control strips and densitometer,” but I haven’t managed to source a reasonably-priced densitometer yet…)

 

[mshchem]

Questions
#1 no worries about age
#2 I've split chemistry, worked, not recommended
#3 Technically no prewash. Practically, using a lift, I have always been concerned about the lift cooling the developer, so I have used a prewash. Nowadays I buy larger quantities of the Developer and use a larger tank than the 1520, use larger volumes of solution. By the book no prewash.
#4 I use stop with RA4 printing, never have with C-41 or E6
#5 Tap water to rinse is standard, keep temperature as close to 38°C as practical.
#6 I do the final rinse solution (Stabilizer) on the reel. Use Distilled water to mix your stabilizer, NEVER a squeegee, 1 minute, hang up to dry no heat.
#7 I just set my Jobo at 38°C. I've been trying to simulate, guesstimate, understand actual developer temperature for decades. I have just decided to be consistent.
#8. Extend bleach and fixer, no problem. Especially if you are getting every bit out of the kit.
#9 Follow the recommended times. I use C41 developer 1 shot these days. I've tried pushing the limit when I was using Tetenal E6 kit (now Adox) I wouldn't recommend it. Follow the instructions. Maximum capacity is easier to attain if you use the mixed chemistry in a week or less.

I'm going to bed, I hope I've helped. I think you're going to do great!

 

[koraks]

Not sure if I should start a new thread

Your questions deserve one, IMO. I've split off your post into a new thread.

Insofar as my answers deviate or expand on @mshchem's above:
#2: I personally mix everything and then stored the mixed/working strength developer in glass bottles. Works better that way. The concentrate part C does not contain a preservative. An argon blanket is a mediocre measure to keep air out. The bottle will go bad before the mixed developer will, in general.

#3 w.r.t. timing: I personally always start the timer upon finishing pouring in the developer and stop it as I start to pour it out. So on average is approx. halfway on both steps. It's not as crucial as people sometimes make you think it is, unless you need absolute consistency across multiple batches. In that case a manual process is virtually impossible to dial in perfectly.

#4 I always use a stop. It helps to limit carryover of developer into your bleach, which in a small volume could result in the bleach drifting up in pH, which would cause problems. However, if the bleach is not overused (without replenishment) this will probably not happen. If you re-use your fixer, you really should include one or two wash cycles between bleach and fix as it protects the fixer.

#5 The filter is fine but won't help against drying marks due to hard water. Temperature is non-critical but it's good practice to avoid big temperature transients.

#6 Distilled water is not a stabilizer. If a stabilizer is used, no rinse should be used after it. Modern (Kodak) C41 films do not require a stabilizer. There's a very long thread about 'final rinse/stabilizer' etc. stickied to this forum.

#7 & #8 Agree with above. Don't overthink it.

#9 for the bleach & fixer just do 'whatever' and extend processing times as you see fit. For the developer there's no hard & fast answer because every subsequent roll of developed film will come out differently from the previous one in a re-use system where the developer is not replenished. There's no way around that. Nobody can decide for you at what point the results are no longer acceptable. Most people get 10-20 rolls of C41 from a liter and are fine with it. That is not a guarantee; it says something about how lax quality requirements in the real world often are.

My take on all this has always been: if there's no problem, there's no need to solve it. I.e. give it your best shot and if you're happy with the result, don't worry.