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I'm thinking of switching from Tetenal to Digibase. My problem is, that i can't find any information about the extended processing times for the Digibase 1l Kit with the exception of the initial times - which makes me a little bit unsettled.

For Tetenal I was used to extend times for every 4 rolls reusing the working solution without replenishing:

For example the developing times (30°C)
Roll 1 - 4: 8'0"
Roll 5 - 8: 9'00"
Roll 9 - 12: 10'00"
Roll 13 - 16: 11'00"

Developing with Digibase, can I use the initial times for all Rolls, meaning all rolls are developing in the same time? Doesn't they have to be extended as Tetenal used to extend them? If yes, why that? Doesn't that mean a loss of quality? Why is tetenal then making a division?

If not, where can I find those extended processing times for digibase? I downloaded the instructions but - as already mentioned - besides the initial times i couldn't find any...

Thank you in advance!

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The capacity of the C-41 process as published by Kodak is 60 rolls of 35mm 24 exposure per gallon. This works out to about 12 rolls per liter. In other words, if the solution is fresh and you wish to process 100 rolls at the same time, the volume needed can be calculated as 100 ÷ 12 = 8.3 (8.3 liters).

Under batch processing conditions, if you are not replenishing the solutions, you must compensate for loss of potency by increasing the time in solution or temperature or both. Because I think the C-41 recipe is about the same for all products, it is my belief that you can follow the chart previously used.

Now for the rest of the story: The developer is a selective reducing agent with the ability to identify exposed vs. unexposed silver salt crystals. Upon identifying exposed light sensitive silver salt crystals, it reduces them ignoring the unexposed crystals. The developing action (reduction) splits exposed crystals into their two component parts. The halogen component is dissolved away into the waters of the developer. The silver component, now metallic silver, is embedded into the emulsion. This flake of metallic silver comprises the foundation of the photographic image.

The halogen component of the crystal is bromine and it is present in the fresh unused C-41 developer solution. The halogen component acts as a restrainer in that it assists the developer as to its ability to differentiate between exposed vs. unexposed crystals. As development continues, more and more restrainer will be liberated adding to the bromine count in the developer solution. This added restrainer plus other spent developer components requires that we add time or elevate temperate or both maintain proper developer action.

Best if we add a developer replenisher. This is a special developer formulation used to maintain the developer’s potency indefinitely. A developer replenisher is a modified formula with the restrainer omitted. We meter a replenisher solution into the working developer solution at a specific rate. This rejuvenates the tank formula and proper activity is maintained as more and more rolls are developed.

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  • \$\begingroup\$ Thank you very much Alan for your detailed answer! Now I understand how this "magic" works! Unfortunately Digibase comes with Bleach and Fixer separated, and I only have the Blix - times from Tetenal which I think are not compatible :( \$\endgroup\$
    – j__
    Nov 22, 2016 at 0:14
  • \$\begingroup\$ Both are 6 minutes 30 seconds at 38 degrees Celsius (100 degrees Fahrenheit). \$\endgroup\$
    – Alan Marcus
    Nov 22, 2016 at 1:19
  • \$\begingroup\$ And they never change as I reuse the chemicals without replenishing? Sorry for asking, but in the Tetenal instructions the blixer times increased drastically for every 4 rolls of film, starting from 4 minutes for the first 4 rolls up to 15 minutes for roll 13 - 16 (at 38°C) \$\endgroup\$
    – j__
    Nov 22, 2016 at 1:23
  • \$\begingroup\$ You can replenish the Bleach and Fix with the same fluid used for the tank formula. Add 5ml Bleach and 35ml Fixer for each roll 35mm 24 exp. Additions should maintain the times. However, C-41 is persnickety, the Bleach is Iron EDTA. The iron needs to be oxidized by sparging to maintain its activity. Sparging is aeration via an air-stone like in an aquarium. Keeping the bleach at specification will be difficult unless you run specialized tests. I think this will be beyond your skill set. Best it the bleach is a one-shot dose, changed out each session. \$\endgroup\$
    – Alan Marcus
    Nov 22, 2016 at 5:14
  • \$\begingroup\$ I just want to make sure I understood this correctly. With the digibase kit you don't have to extend developing/bleach/fix times because of the makeup of the chemicals? If the chemicals retain their potency, wouldn't that mean that you could basically use them for way more rolls than recommended? And what am I supposed to do with the bleach? Mix up new bleach for every time I develop? \$\endgroup\$
    – RosaAnd
    Jan 18, 2019 at 20:00

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