On C41 shelf life

Berri · Nov 29, 2018

I know, there are other threads on this topic, and I did look at them, but at the end some say one thing while others say the opposite.

I already use C41 in a Paterson tank with great success, but now I am moving on and bought myself a rotary tube processor Jobo CPP2 with the lift mechanism.

The C41 kit I usually buy is made by bellini and comes with a developer monobath, and it is only sold in 1L kit which make it a bit to expensive to use as I will be doing one shot with my Jobo (250mL two rolls at time or 600 mL 5 rolls at time)
I am considering buying a larger kit (5L) made by Compare, the Digibase which comes with developer split in three parts.

Now, my question is, does it have a longer shelf life when mixed or in concentrate form?

How long do you think I could keep the concentrate once opened?

Thank you!

thuggins · Nov 29, 2018

Berri said:
I know, there are other threads on this topic, and I did look at them, but at the end some say one thing while others say the opposite.

I'm sure you'll have the same problem here as folks seem driven to repeat what the heard once or what they believe should happen. That being said, I have no experience with C-41 (I have very negative feelings about it). But I have done a lot of E-6 in the Tetenal kit, so these comments are offered with full transparency.

Tetenal says you get 6 rolls per mix. I process 10 and never had an issue. Ten rolls takes about five weeks. The last batch I used was about 2 months old by roll 10. It was a bit disappointing (not real sharp). I suspect this was the camera as roll 9 done the day before was beautiful. I think 2 months and 10 rolls would be a practical limit for a mix.

On the first kit I had one of the blix components (BLX 2?) had begun to precipitate out what I assume is some sulfur compound by the time I got to mixing the last batch. So the concentrate had been opened about 6 months. Pretty much everyone will jump on this and say the kit is no good, not so in my experience. The kit mixed up fine and the film all processed properly. A year later the film still looked good. Since then I have been decanting the concentrate into 100 ml bottles and had no further issues.

Photo Engineer · Nov 29, 2018

A C41 liquid kit with a 1 part developer (I assume that is what you mean by monobath) is just not stable. I tried for quite a while to do this while working at EK. The alkaline conditions make it nearly impossible to get good shelf life.

PE

Berri · Nov 29, 2018

Photo Engineer said:
A C41 liquid kit with a 1 part developer (I assume that is what you mean by monobath) is just not stable. I tried for quite a while to do this while working at EK. The alkaline conditions make it nearly impossible to get good shelf life.

PE

Thank you for your replay,
Yes I mean one part developer and I am aware of its poor stability, that is why I decided to shift over to Compard C41 which is three parts. How long do you think it will keep after being opened? I can store the concentrate in a fridge if this can help or add protective gas.

Berri · Nov 29, 2018

thuggins said:
I'm sure you'll have the same problem here as folks seem driven to repeat what the heard once or what they believe should happen. That being said, I have no experience with C-41 (I have very negative feelings about it). But I have done a lot of E-6 in the Tetenal kit, so these comments are offered with full transparency.

Tetenal says you get 6 rolls per mix. I process 10 and never had an issue. Ten rolls takes about five weeks. The last batch I used was about 2 months old by roll 10. It was a bit disappointing (not real sharp). I suspect this was the camera as roll 9 done the day before was beautiful. I think 2 months and 10 rolls would be a practical limit for a mix.

On the first kit I had one of the blix components (BLX 2?) had begun to precipitate out what I assume is some sulfur compound by the time I got to mixing the last batch. So the concentrate had been opened about 6 months. Pretty much everyone will jump on this and say the kit is no good, not so in my experience. The kit mixed up fine and the film all processed properly. A year later the film still looked good. Since then I have been decanting the concentrate into 100 ml bottles and had no further issues.

So, based on your experience, would you consider possible to keed the half full concentrate for at least six months?

twelvetone12 · Nov 29, 2018

I have a Tetenal E6 kit that has been open for over 6 months and I still have 1/3 of the concentrate left. Works still very well, but I use it for non critical work (and hope to finish it soon). It is stored in the darkroom which is quite cool.

Photo Engineer · Nov 29, 2018

Berri said:
Thank you for your replay,
Yes I mean one part developer and I am aware of its poor stability, that is why I decided to shift over to Compard C41 which is three parts. How long do you think it will keep after being opened? I can store the concentrate in a fridge if this can help or add protective gas.

In my experience, a three part kit could keep for about 6 months or so with an inert gas blanket over it. It is noted by turning dark brown or black when it goes bad. Keeping varies. Refrigeration does not help much in this case.

PE

Berri · Nov 29, 2018

Photo Engineer said:
In my experience, a three part kit could keep for about 6 months or so with an inert gas blanket over it. It is noted by turning dark brown or black when it goes bad. Keeping varies. Refrigeration does not help much in this case.

PE

That is great! Six months is enough for me, I will buy the 2.5L kit which will allow me to process 20 films one shot

halfaman · Nov 30, 2018

I have used many times and use currently the Rollei/Compard Digibase kit in 5 liters and 2,5 liters form, I can say to you that the shelf life of the CD concentrates is excellent. You can have them open for 4-5 months easily without any kind of inert atmosphere and results are still consistent (CD-4 is in part C). Really good stuff.

Berri · Nov 30, 2018

halfaman said:
I have used many times and use currently the Rollei/Compard Digibase kit in 5 liters and 2,5 liters form, I can say to you that the shelf life of the CD concentrates is excellent. You can have them open for 4-5 months easily without any kind of inert atmosphere and results are still consistent (CD-4 is in part C). Really good stuff.

Great news! At the rate of about two rolls per week or more the two liters kit should last me about three months, so I am happy with it!

halfaman · Dec 1, 2018

There is one negative thing: Process intructions are not very good. For example, there are no washes indicated at all and times for bleach and fix are a bit confusing.

Just follow the standard C-41 steps.

Berri · Dec 1, 2018

halfaman said:
There is one negative thing: Process intructions are not very good. For example, there are no washes indicated at all and times for bleach and fix are a bit confusing.

Just follow the standard C-41 steps.

I use a acetic acid stop bath between developer and bleacher, than straight into fixer, wash and stabilizer.

Photo Engineer · Dec 1, 2018

Berri, this process will shorten the life of the fix!

If you don't care, then there is no problem.

PE

halfaman · Dec 2, 2018

What I do in the Jobo is as follow:

CD + Stop (3% acetic acid) + wash (2x30 seconds) + Bleach + wash (3x30 seconds) + Fixer + wash (7x30 seconds) + Stabilizer (inmersion in a separate beaker). I use standard 6:30 time for bleach and fixer, even Compard suggest lower times at 38º C (4 and 5 minutes respectively). But I don't trust the datasheet very much as I said.

Perhaps you can avoid the wash between the bleach and fixer if you are using the working solutions as one-shot, but I prefer to be in the safe side and do the whole process. Also the time you save skipping the wash is neglible.

Berri · Dec 2, 2018

Photo Engineer said:
Berri, this process will shorten the life of the fix!

If you don't care, then there is no problem.

PE

Thank you for your replay,
Exactly, as I said before I will be using a Jobo and I will do one shot, so there is no point in washing after bleach. As a matter of fact that is Wath Kodak suggests in the z131 publication, the only change I introduce is the stop bath to avoid streaks.

On C41 shelf life

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