Hand Processing C41 Timing Questions

DH_Studio · Dec 7, 2020

I wanted to see if anyone has some suggestions on how to deal with timing the chemicals for hand processed C41.

1). I'm using an Arista kit and a stainless steel tank that takes two rolls of 120 and having some trouble with timing.

Not sure if I should start the timer for developer and blix as I start pouring the chemicals in - or after. I try to be quick without being sloppy, and it seems like it takes some time to fill that quart tank without spilling all over the place. Maybe 20 seconds or so. It seems like that means the reel on the bottom spends more time submerged than the reel on top, and the same again when it gets poured out.

The instructions call for 4 inversions every 30 seconds. But the inversions also take another 10 seconds or so. So Every 30 seconds as in:

- 4 inversions at 3 minutes, then 2:30, then 2:00, then 1:30 etc.

or

- 4 inversions at 2:30, finishing at about 2:20, then another 4 inversions 30 seconds later at 1:50, finishing at 1:40, and starting the next 4 inversions 30 seconds later at 1:10, etc.

I might be way overthinking this, but I've heard that color is a lot more temperamental than B+W, so trying to be precise. Is that necessary or am I overdoing it?

2). Can anyone share their personal experience with how long they've stored C41 chemistry and what the results have been? I've heard a wide range of wild speculation on a few forums, and people saying things like "With all the time and money invested in shooting your rolls, don't risk it, throw it out and use fresh chemicals all the time" so that take on it is duly noted. But it would be great to hear how long folks have successfully used their developer. I'm not trying to keep it around for months, but a couple of weeks (adding the recommended developing time for each new batch) would be helpful.

I store the chemistry in air tight amber quart bottles (the kombucha kind) in a closed box inside of a cool, dry closed cabinet

Thank you!

Rudeofus · Dec 8, 2020

The times given in the manual are defined as: from the first time the chemistry touches the film until the first time the next chemistry touches the film. The only step with critical timing in C-41 is the color developer step. If this step is specified as 3:15, I usually pour out the chemistry at 3:00, then wait until 3:15 to pour in the next bath. Regardless of what tank you use, 10-15 seconds should be enough for complete pouring out of any process liquid.
Some manuals have "quite interesting" suggestions for agitation, you do not have to follow them to the letter. With inversion tanks it is also quite important, that the tank is upright most of the time, because otherwise the bottom part of the film roll is not submerged in the process liquid. The most important aspect is, that you maintain a consistent and repeatable process. If you have that, any potential issues can be addressed by slight changes to the process. If your processing is all over the place, corrections are impossible.
Color chemistry does not suffer from sudden death. It becomes weaker over time, and frugal photographers extend processing times to make their chems usable for months. So it is entirely up to you: for near perfect results you should use mixed chemistry within 1-2 weeks, anything longer will give less and less reproducible results. If your throughput is low, I recommend you get inert gas and mix concentrate only as needed.

BMbikerider · Dec 8, 2020

Rudeofus said:
The times given in the manual are defined as: from the first time the chemistry touches the film until the first time the next chemistry touches the film. The only step with critical timing in C-41 is the color developer step. If this step is specified as 3:15, I usually pour out the chemistry at 3:00, then wait until 3:15 to pour in the next bath. Regardless of what tank you use, 10-15 seconds should be enough for complete pouring out of any process liquid.

Some manuals have "quite interesting" suggestions for agitation, you do not have to follow them to the letter. With inversion tanks it is also quite important, that the tank is upright most of the time, because otherwise the bottom part of the film roll is not submerged in the process liquid. The most important aspect is, that you maintain a consistent and repeatable process. If you have that, any potential issues can be addressed by slight changes to the process. If your processing is all over the place, corrections are impossible.

Color chemistry does not suffer from sudden death. It becomes weaker over time, and frugal photographers extend processing times to make their chems usable for months. So it is entirely up to you: for near perfect results you should use mixed chemistry within 1-2 weeks, anything longer will give less and less reproducible results. If your throughput is low, I recommend you get inert gas and mix concentrate only as needed.

I have successfully stored mixed and ready for use C41 developer for up to 3 months - yes 3 months and it would have gone on for much longer. The secret is how you store it. I use a JOBO rotary processor and the minimum quantity to be used for a 35mm film is 160cc. I mix the concentrates to give me 500cc and then decant them into a 150cc dark brown glass bottle. (They will usually take 160cc.) These bottles have the plastic insert in the cap which when screwed on are fully air tight. I heat the bottle containing the developer to between 50-60C which drives out most of the free oxygen and when still warm I screw on the top. When the developer cools down the liquid looses volume and forms a partial vacuum inside the bottle. You will know when you have created a good seal because when you unscrew the cap there is an inrush of air. When it goes into the bottle the developer is a light to mid straw colour and when opening the last bottle it is rarely very much darker. I have spoke to Tetenal UK about this and in their words "You are on the right lines"

It sounds a bit of a faf, but it allows me to cut costs by buying a larger kit in the first place. If I am only developing 1x35mm I discard the developer but if I am developing a 120 film or 2 x 35mm films I double the amount for the larger tank and use twice only. It is simply not worth extracting the very last vestiges out of the developer because of the risk of failure increases and film is more costly than developer.

Hand Processing C41 Timing Questions

DH_Studio

Rudeofus

BMbikerider

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