Is this replenishment scheme going to cause excess development strength?

[hwy17]

The new Kodak 5L kit from Photo Systems does not appear to use a starter solution. The manual calls it a non replenishment kit but Cinestill who is marketing the kit in the USA says you can use it for self replenishment. If the kit is just three part flexicolor developer replenisher then that makes sense, except for the questions raised by the lack of starter.

Cinestill advises a 40ml per roll of 135 replenishment rate.

Here's the replenishment concept:

Mix 1 liter of solution

Take 500ml of solution and process 4 rolls of 135 film in a single rotary batch.

Discard 160ml of used solution.

Return 360ml of used solution to 500ml of fresh solution, leaving an 860ml volume of mixed solution.

Top off 860ml of working solution with 500ml of fresh mixture, creating 1360ml of mixed solution.

Continue this cycle with the main working batch of solution varying in a range of 500ml minimum, 1.5L maximum, discarding 160ml after every 500ml/4x135 processing batch. Main working batch being topped off in 500ml increments.

The math here is hectic and the true replenishment rate would vary inconsistently, but as far as I can tell would always meet or exceed the strength of the prescribed 40ml replenishment rate.

My alternative plan is just to mix 500ml fresh, process 4x135, and discard. Which is more consistent but less efficient. Also if I judge it correctly, an overall stronger solution than the variable strength solution scheme as proposed above.

 

[hwy17]

As for the lack of developer starter in the kit, the justification that I can imagine must be that the processing volumes are low enough that the developer gets "used" enough in the process.

I.e. If a lab were to mix up 40 liters of developer without a starter and then put a roll of film through that, the developer would be too strong and fresh, but if you use 290ml of fresh developer without a starter on a single roll of 135 film in a single roll Paterson tank, the 1 roll / 290ml ratio is still a high enough "usage" of the chemistry that the developer reaches working strength during the process.

It's also possible that the lack of starter is not truly defensible. Or it's also possible that the kit has been communicated incorrectly, and the three part developer included in the is in fact somehow a developer starter and not a developer replenisher and so is not technically suitable for self replenishment.

I have not reached certainty about this, but Cinestill who markets the kit definetely indicates that it does not include a starter component and can be used for self replenishment.

 

[koraks]

Or it's also possible that the kit has been communicated incorrectly, and the three part developer included in the is in fact somehow a developer starter and not a developer replenisher and so is not technically suitable for self replenishment.

This is the case, although to get the terminology correct: the developer is not a 'starter', but just a working strength developer. There's no chemical solution to making a developer that works at the same time as a working strength developer and also as a replenisher. So the self-replenishment story of Cinestill has a hole or two in it somewhere. I expect they assume that people won't notice anyway.

Continue this cycle with the main working batch of solution varying in a range of 500ml minimum, 1.5L maximum, discarding 160ml after every 500ml/4x135 processing batch. Main working batch being topped off in 500ml increments.

It's not entirely clear to me how your main volume shrinks back towards 500ml. You described how you go up in 500ml increments, but not back down.
I'm also not sure what the purpose of this system of 500ml increments is. I would just replenish in 160ml increments. You could get 150ml glass bottles (which will usually hold around 160ml if you top them off entirely) and decant your mixed, working strength developer (aka 'replenisher') into those bottles. A properly formulated C41 developer will store for a long time that way (glass bottle, proper & tightly fitting cap, filled to the brim with no air on top), generally well over a year. So just use a 500ml or 1000ml main volume and take out the 40ml per roll that you've 'used up' and replace with fresh developer.

Given the inherent limitations of this chemistry there will be some process drift, but it's entirely likely that this will go unnoticed and will not be experienced as a problem. Is it a 'proper' way of doing C41 in official terms? Nope. But it will probably work plenty good enough for home/amateur use.

Refer also to this thread in which the replenishment situation of current Kodak FlexiColor C-41/C41 is being discussed: https://www.photrio.com/forum/threads/kodak-color-negative-c41-kit.214105/

 

[hwy17]

There's no chemical solution to making a developer that works at the same time as a working strength developer and also as a replenisher.

This is key to the hole in my own understanding. I have tried to read Flexicolor documentation and failed to firmly grasp it. And in the thread you linked I still feel like I'm ignorant to some basic common assumptions everyone is operating on.

Can you help me shortcut this basic question: What is a flexicolor replenisher strength solution then, is it a solution mixed at a higher strength or is it actually even 40ml of the raw concentrate solutions?

It's not entirely clear to me how your main volume shrinks back towards 500ml. You described how you go up in 500ml increments, but not back down.

The working volume shrinks as 500ml is taken for processing, used, and then 160ml is discarded after use (40ml for each one of 4x 135 rolls processed). So after each batch of processing the volume shrinks by 160ml.

The reason I wanted to replenish in 500ml volumes results from my assumption above that replenishment solution is mixed same as original developer batch strength. I could more confidently mix batches of solution to make 500ml compared to mixing 160ml which would require more precision.

Thank you for your help.

 

[koraks]

What is a flexicolor replenisher strength solution then

In the current version of Flexicolor as made by PhotoSys under the Kodak brand, there is no true replenisher. There is only a working-strength developer.

A proper replenisher has two characteristics that set it apart from a working strength developer:
1: It's more concentrated; i.e. the active ingredients (in particular the CD4 developing agent) are present in higher quantities per liter.
2: It lacks or has a lower concentration of halides (typically bromide and a tiny bit of iodide). The idea here is that the halides are added to the developer during development as they dissolve out of the processed film, or they are added in the form of a starter, which is mostly a solution of bromide (potassium or sodium).

So after each batch of processing the volume shrinks by 160ml.

And the idea of replenishment is that you replace that with 160ml of replenisher. In the case of present-day Flexicolor developer, you could use the developer for that, which means that activity will trend down for the first few sessions until things stabilize at a certain level that's slightly less active than the initial main volume when it's used for the first time.

As to mixing volumes: in my experience it works well to just mix the entire kit at once and then store it properly as I described earlier. Then use whatever you need as you go along. In addition to glass bottles, some people also have good experiences with so-called 'stop-loss bags' or wine bladders. I myself prefer glass, but that's personal; those wine bladders in principle should work fine too. There's even one person who has frozen his mixed working strength developer and this has been working very well for him.

Thank you for your help.

You're welcome!
Try not to overthink things.

How much film do you expect to process on a monthly basis?

 

[hwy17]

In the current version of Flexicolor as made by PhotoSys under the Kodak brand, there is no true replenisher. There is only a working-strength developer.

Ah! That is slightly reassuring if the situation is indeed just complicated. I could not get the replenishment logic to just click like it seemed like it should. I'll keep rereading the referenced thread to try to expand my understanding.

How much film do you expect to process on a monthly basis?

I've got 20 rolls of 35mm ready to process now and then maybe 8 per month. I would definitely welcome any advice about a processing scheme. Using 500ml of fresh solution at a time to process 4 rolls and then discard is still an acceptable option for me and would also save me some mental effort in it's simplicity. That's what I had settled on until I decided to revisit replenishment. This will be my first time processing film at home.

 

[hwy17]

I notice now that the Flexicolor document actually references a separate non-replenishment product here on page 5:

https://business.kodakmoments.com/sites/default/files/wysiwyg/pro/chemistry/z131.pdf

KODAK FLEXICOLOR Chemicals for RotaryTube Processors, Small Tanks, and Unreplenished Sink Lines These chemicals are designed for use in unreplenished batch systems—e.g., small tanks, rotary tubes, and small-volume sink lines. They are ready to use as mixed without adding starter. Note: For higher-volume replenished sink-line systems, it is more practical to use larger chemical sizes. You can prepare tank solutions of developer and bleach by adding the appropriate starters to the replenisher solutions. KODAK FLEXICOLOR Developer Use this developer in unreplenished systems. No starter is needed. • Available in a size to make 1 U.S. gallon.

So if I read this and the instruction manual explicitly and ignore Cinestill's interpretation I can reach one simple conclusion: Don't try to self replenish with this kit.

Those with greater understanding here can probably see a lot more nuance but in my beginners position maybe I should stick to my beginner's plan. Use 500ml to process 4 rolls and discard.

 

[koraks]

Don't try to self replenish with this kit.

Well, you could and as said it'll sort of work, but it's not a "proper" replenishment system.

 

[hwy17]

Well, you could and as said it'll sort of work, but it's not a "proper" replenishment system.

To clarify something do you think the replenishment system I've described works (acceptable results, not perfection) with all solutions mixed at the same working strength? Replenishing 40ml of the same strength solution as the original solution. I just wasn't sure if your above correction about replenisher can't be same strength was about precisely correct processes, or something I should change in my modified process.

As you can tell already I go back and forth on this repeatedly. Like now I imagine 500ml sloshing around in a 1L Jobo rotator is gonna face a lot of air oxidation in the process too.

I think that maybe I will start with the one shot process to gain confidence about it then when I finish my first 5L kit and I can decide how I feel about the next kit and whether I'd enjoy being able to stretch it longer.

Thanks again I appreciate it.

 

[koraks]

If you scan your negatives and don't intend to optically print them in the future, then you have a considerable leeway to begin with and you would probably get perfectly fine results that way. If you are planning on optical printing, it can be frustrating if your negatives are kind of variable in terms of density and color balance. Or put differently - it's generally convenient/nice if your film prints in a more or less predictable way. With scanning, color and contrast adjustments are relatively easy to do anyway, so you'll get fine results even from negatives that are perhaps not super consistent etc.