Sunday, January 11, 2015

Daylight Development Tanks - Agfa Rondix 35 & Caffenol

As mentioned in the introduction to the topic, I purchased, 2nd hand, an Agfa Rondix 35 daylight development tank. On the interwebs, it seems that some folks had questions about the performance of the tank when used with Caffenol.
Eager to test the tank, in particular with caffenol, I loaded an ISO200 C41 film into my Canon QL17 and went out shooting.

You might be familiar with the fact that you should over expose by 2 stops when planning use caffenol on a C41 film. That precisely I did, I exposed the film as if it was ISO50.

The Agfa Rondix holds 200ml of fluid only.
So, the following recipe was used today.
  • 200 ml water
  • 2 tsp washing soda
  • 2+ tsp coffee crystals
  • 1/4 tsp ascorbic acid
The temperature of the mix was more than room temperature, however, I did not measure it. Concerning temperature, I developed films between 18C and 26C at the same timing.

Processing with the Rondix requires constant agitation. Still I kept my timing the same (slightly reduced ascorbic acid in the recipe thought).
  • 17 min Rondix type agitation
  • 3 water changes for washing w/ several cycles (wash should pour out clean)
  • 3 min fixing
  • 5 water changes for washing w/ several cycles
  • 1 last wash w/ a drop of dish washing soup, several cycles
The process resulted in really nice negatives.
Washing according to the Ilford method takes less time in a regular (reversible) tank. However, I am confident that the Rondix provides all one needs for developing film in daylight easily.

Observation: My tank was sold to me with the remark that it might be unused. I believe that, since there was no smell to the tank at all. However, that also means that the seal never has seen any moisture. My tank leaked a little bit at said seal, with a little I mean like 5 drops during the entire processing. Still, I should try to find a solution (new seal) to this issue.

As soon as the film is dry, I will provide some scans.
2 more tanks to test, stay tuned!


  1. Hi there. Really interesting post. I will have my first dev ever with an essex35 in caffenol very soon (just waiting royal mail to deliver the tank).
    Just a thought about the overexposure it is the same thing to expose at boxspeed and reduce the dev time accordingly? If yes how much can be shortened? Thanks

    1. Marco, sorry that you had to wait for such a long time.
      The point in developing C41 film with B&W chemicals is that one develops a "silver image". C41 film is built with 3 layers of colour sensitive material in which the silver will only be the catalyst for the C41 processing (the silver will actually be removed by the bleaching step in the process).
      In B&W, we want to keep the silver. Also, the silver is not just a catalyst, it is the pigment. Therefore, you would want to over-expose by 2 stops, when planning to use colour-neg (C41) film in a B&W development process.
      This is entirely independent on what tank or chemicals you will be using.
      Cheers, Dr. J.

  2. Hey, I can't seem to find them, did you ever post the pictures you developed? If so can you link me to them? Thanks :)

    1. Hi Jordan,
      thanks for your multiple posts.
      No, I dit not post any scan, despite the promise.
      It's been over a year by now, I can't recall which film it was... so, I won't be able to answer to your request.
      Anyway, you might just want to develop a roll yourself and see that it works.
      Cheers, Dr. J.