Another Tetenal C41 thread....

I am now the proud owner of a 2.5L kit and i've a few questions about how best to use it.
I'm not planning to mix the full 2.5L in one go as it will likely go bad before i can use it to capacity. I understand if i purge the air from the concentrates and keep them cold will stay good for quite a while.

If i mix up say 1L of the kit, using my Jobo CPE2 with a 1520 drum assuming i develop 2 films at once, am i best to keep re-using the same shot of chemicals till they are exhausted, or add them back the 1L mix and re use from that?

How to i compensate the time for used developer and blix? The instructions say to increase the time by 15 seconds every 4 rolls of film (assuming i'm pouring back into the 1L mix but can easily be calculated back for any volume). Is this regardless of doing 1 or 2 films at once.
The instruction for the blix are a little more confusing though and don't follow the same pattern. From what i've read online it's quite possible i'll get a lot more film out of the kit than the kit says, but it doesn't give any times for blix beyond 16 rolls. Any advice here?
How does the ISO effect the times, higher ISO films deplete it faster, so surely the times should also be similarly be effected?? Same again if pushing a roll of film...

I know i know, lots of questions from a newbie. This is my first time doing C41 and really don't want to ruin any film or expensive chemicals!

Ta muchly

Another thought i just had....

My 1520 drum needs 240ml (lets call it 250ml for round numbers) regardless of whether i'm doing 1 or 2 rolls at a time when rotary processing.
Most of what i have read online says to mix up 1L, pour the needed 250ml into the drum and return it when done. But using it this way would mean after doing 4 rolls of film the full litre is now diluted with partially depleted chemicals and thus the developing time should be extended by 15 second.
BUT.... Assuming you're doing a batch of film, if each shot of chemicals is used once then kept in a separate bottle and taking the next shot from the fresh mix this would allow you to process 8 rolls of film before any extra time is required.

Would this surely not be a more efficient way to use the chemicals to the fullest and get the most consistent results as you would be using more of it before they came into contact with film and became partially depleted.
It would also possibly reduce oxidising?

I suggest you do the following:

1. Mix 500ml
2. Use 250ml each time then pour back into the bottle with the rest of the solution
   
3. Increase development time as follows:
   1. 1-2 films (either simultaneously or consecutively): 3' 15"
   2. 3-4 films: 3' 30"
   3. 5-6 films: 3' 45"
4. Discard and mix a fresh 500ml batch for the next 6 rolls
5. Adjust bleach fix times according to the table in the instructions

As a starting point, I think this should work quite well. For consistent results, I would try and process two rolls of film at a time rather than one.
No doubt you will receive other recommendations as well. You will soon arrive at a procedure that works best for you.

Redfox61 said:

I suggest you do the following:

1. Mix 500ml
2. Use 250ml each time then pour back into the bottle with the rest of the solution
   
3. Increase development time as follows:
   1. 1-2 films (either simultaneously or consecutively): 3' 15"
   2. 3-4 films: 3' 30"
   3. 5-6 films: 3' 45"
4. Discard and mix a fresh 500ml batch for the next 6 rolls
5. Adjust bleach fix times according to the table in the instructions

As a starting point, I think this should work quite well. For consistent results, I would try and process two rolls of film at a time rather than one.
No doubt you will receive other recommendations as well. You will soon arrive at a procedure that works best for you.

Click to expand...

This would only yield 30 rolls though which is at the bottom end of the expected capacity of the kit?

Yes. You could probably run 7-8 films through each 500ml, extending the development time to 4 minutes. In that case I would definitely process two rolls at a time rather than one, to minimize oxidation of the developer in the tank.

Or perhaps just follow your initial plan: mix 1l and process 2 rolls at a time as far as you can, using 250ml each time and pouring it back with the rest. Follow the development times recommended in the table. If you want to, you can make finer adjustments for "in-between" numbers of films, using the the development times recommended. You could extrapolate from those times in order to make finer adjustments, especially if on occasion you process a roll by itself. But I really don't think that's necessary.

TattyJJ said:

The instruction for the blix are a little more confusing though and don't follow the same pattern. From what i've read online it's quite possible i'll get a lot more film out of the kit than the kit says, but it doesn't give any times for blix beyond 16 rolls. Any advice here?

Click to expand...

You can't blame the instructions for not covering topics you "found on the internet". Yes, people have reused the color developer much more than suggested by the instructions, and at least with scanning they could get acceptable results. BLIX, however, is mean, because you can't immediately see whether it worked completely or not, only a few years later you will get stains that can't be removed. Therefore people are reluctant to play games with BLIX. One way to extend the life of your BLIX kit would be to (there was a url link here which no longer exists), but even in this case you shouldn't overuse the fixer.

Haven't used a Jobo rotary drum since the 1980s, hand process only nowadays, but here's my twopenn'orth.

From a 2.5 litre kit I mix 1 litre's working solution. That's sufficient for 3 x 35mm films, or 2 x 120. Only process when you've accumulated the required number of films for economy, I find usage exhausts the chemistry almost as much as amount of film, so I wait until I have three exposed 35mm films. I throw away the 1 litre of chemistry at 25 films (fewer if there's been a long interval between films), and mix up another batch. In the past I've extended processing times slightly with age, but the system isn't an exact one (or why would 1 film need the same time as 4, and five require a 15 second step?). If you see any variation in base colour or density that isn't accounted for by exposure, extend the time or change the chemistry. Keep the mixed chemistry in concertina bottles with liquid up to the cap.

I mixed up a second 1 litre batch from a 2.5 litre kit today, and the concentrate has been in a part empty bottle for the last year in a dark, cool place (not refrigerated). The chemicals showed no discoloration, and the films had no processing issues. Previously I've used 5 litre Tetenal kits, but even at my prodigious film use 20-25 films per litre meant up to 125 films from a pack! Economical if you have Garry Winogrand's work rate, but too much volume for most of us.

After consumer pressure Tetenal have re-released their 1 litre kits, meaning the juggling act with the 2.5 litre solutions is unnecessary.

I buy 1L kit and use it for 14/16 rolls mixing 0.5L at times and processing 1 120 film or 2 135. It Last a long time stored in brown glass bottle (please don't use beer bottles!) tightly stoppered and topped with inert gas.