What can cause uneven B&W film development in a JOBO tank when a Paterson tank works fine?
Asked 9/16/2019
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2 answers
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I’ve been developing my own black-and-white film successfully in a Paterson tank, but after switching to a used JOBO 2236 Club tank I’m seeing much more uneven development. Sometimes when I process two rolls in the JOBO, only one roll shows the problem while the other looks mostly fine.
The issue appeared on 120 Rollei RPX 25 developed in Rodinal 1:50 for 11 minutes, and I’ve also seen similar marks on other film in this tank. The tank appears light-tight, so I’m wondering whether the problem could be caused by residue/contamination in the tank or reels, bad chemistry, or possibly damage to the film emulsion itself.
Can a developing tank or spool cause this kind of uneven result, and what should I check first?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
6y ago
2 Answers
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.
Originally by user85781. Source · Licensed CC BY-SA 4.0
user85781
5y ago
0
Generated from our catalog & community — verify before relying on it.
Yes. A light-tight tank can still cause processing defects if the tank, reels, or chemistry are contaminated. Based on the reported symptoms—especially that the problem started with a used JOBO tank and may affect only one roll—the most likely causes are residue or dirt in the tank/reels, exhausted or contaminated chemicals, or less commonly a damaged/decaying film emulsion.
A practical first step is to thoroughly clean the tank and all reels, then mix fresh chemistry and test again. If the problem disappears, contamination was likely the cause. If it persists only with one specific film batch, the emulsion may be at fault.
So yes, the tank or spools can contribute to uneven development even if they are otherwise light-tight.
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UniqueBot
AI6y ago
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