I have been developing my own bw film for some time, so far in a Patterson tank and without problems. Recently, I got a used JOBO-2236 Club tank...I have used it a bit, but I have gotten far more development issues (uneven development etc) with the JOBO tank then I ever got in the Patterson. Strangely, when developing two rolls in the JOBO, often only one roll is affected. Does anyone have a clue what could cause this? Can a tank (which is light-tight) have some other problems? Can the Spools have a problem?

Or does anyone have an idea what could have caused this?

I attached a sample, the photos were taken on a 120 roll of Rollei RPX25 and developed in Rodinal 1:50 for 11 minutes. All my previously shot RPX25 (developed in Paterson) looked great...interestingly, the second roll of RPX25 in the same developing process is more or less fine. The problems on Pancro 400 in my other post are also in this tank...


Unedited Scan: enter image description here Converted pictures: enter image description here enter image description here

  • \$\begingroup\$ Can you describe what is is about the example photos that you find unacceptable? \$\endgroup\$
    – Michael C
    Sep 16, 2019 at 21:19
  • 1
    \$\begingroup\$ @MichaelC On larger surfaces (clouds) you see something like dark points or dots...one could think it was super large grain...but its an ISO 25 film! Especially in the light cloud above the building in picture 1, and in the big cloud in the center in picture 2 \$\endgroup\$ Sep 16, 2019 at 21:51
  • \$\begingroup\$ 'Super large grain' is often reticulation, but these have some kind of linear pattern to them, so, well, no idea at all. \$\endgroup\$
    – user82065
    Sep 17, 2019 at 8:36
  • \$\begingroup\$ Are you 100% sure it is actually the tank and not some dud rolls causing these artefacts? Perhaps some residue is left in the tank. Clean it thoroughly. \$\endgroup\$
    – timvrhn
    Sep 17, 2019 at 15:07
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    \$\begingroup\$ It's difficult to say. The tank seems light tight indeed, I'm actually thinking of chemicals contamination and/or bad rolls. Try developing again in the old tank. If the issue persists, your chemicals are contaminated. If it does not, it may have been some coincidentally bad rolls or your new tank is contaminated with some chemical. \$\endgroup\$
    – timvrhn
    Sep 18, 2019 at 19:04

1 Answer 1


The tank or chems were filthy with residue or the roll had a decaying emulsion. If I saw this in the lab I would immediately clean the equipment and change the chems.


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