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25 r.p.m. Jobo processing and film development inconsistencies

Tom Kershaw

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I have recently experimented with using the 25 r.p.m rotation speed setting on the Jobo in an attempt to deal with potential oxidization issues when running at 50 r.p.m for Pyrocat-HD development. However, approximately 2 of 8 or so rolls show development inconsistencies that do not occur when the process is run at 50 r.p.m and I note from a 2008 posting on APUG that 'Lee L' had issues when running at 25 r.p.m.

Any other experiences of developer inconsistencies when processing at 25 r.p.m?

Tom
 
I use abc pyro plus at the film speed setting. No issues with 8 x 10 sheet film.
Pat
 
What problem did you have at 50? Uneven development from premature exhaustion? If so, I'd increase the amount of deveoper in the tank.
 
See the article here: http://www.jobo.com/jobo_service_analog/jq/jq9403.htm#Issue3
on B&W processing with the Jobo.


My problems were with a CPE-2, 2500 series tanks and reels, 25 RPM, and no pre-soak. My problems were standing waves that introduced prominent flow patterns of varying development density on 4x5, 120, and 35mm film. 25 RPM and no pre-soak were standard Jobo recommendations when I had the problem in 1982-83.
I've only done one test run (on Pan-F + Rodinal) in the last few years using the later Jobo recommendations, pre-soak and higher rotation speed (~65 RPM on the CPE2), and the negatives looked very good and even. I have gone to agitation as a control for contrast/film speed, so the Jobo no longer fits my standard B&W film development routine.

Lee
 
Tom Kershaw said:
Lee,

Thanks for the link. The Jobo works due to convenience and usual consistency, however I am aware of the benefits of less automated film development techniques.

Tom
Click to expand...

Sorry, I wasn't suggesting that you change. Just stating the reason that I haven't had occasion to follow up on testing more thoroughly, and can only offer a sample of size 1, which we both know isn't really 'proof' of anything.

Lee
 
Tom,

Let me suggest that you pour the developer in while the tank is spinning at maximum RPM and after 30 to 60 seconds reduce rotation speed to 25rpm's. This may solve your problem.
 
Gary,

I use the ATL-2300 which automatically pumps the solution into the tank. The Jobo Quarterly article from 1994 linked to above suggests that a fast rotation speed (i.e. 75 r.p.m) shouldn't negatively impact on image quality; however, I suspect Jobo didn't take staining developers into consideration.

Tom
 
Tom,

I have developed films for 20+ years using 1500 series Jobo drum in a custom processor at 30 rpm. Never had any trouble. In the last few years I dropped the rotation speed to 8 rpm because I want to limit the solvent action of sodium sulfite in developer and fixer and fast oxidation of some developers. Again, no inconsistencies whatsoever. I really do not understand the need to go anything faster than 30 rpm.

Ciao.

Mantinieri

http://www.mantinieri.com
 
Mantinieri said:
Tom,
I have developed films for 20+ years using 1500 series Jobo drum in a custom processor at 30 rpm.

Mantinieri

http://www.mantinieri.com
Click to expand...

My recollection is that reports of problems with uneven development were tied to the 2500 series drums and reels. Jobo redesigned the original 2509 reels, which were replaced by a 2509N model reel for this reason. In my case, the slower speed resulted in uneven development across the width of the film, and included standing wave patterns that matched the radial spokes on the 2500 series reels on 35mm and 120 film. I also found flow patterns in 4x5 sheet film on the original 2509 reels at the slower speed on a CPE2 that made them unusable.

I don't recall any reports of problems with the 1500 series tanks and reels.

Lee
 
A quick and easy fix is to run a nitrogen gas feed through the the jobo lift, up to the opening of the drum. Quarter inch hose feeding 250cc of gas will give you fog-free stained negs.
 
Nitrogen ?

Quick and easy ? sure, once you've got yourself a supply - doesn't that mean either purchasing or hiring a tank ?

As for Pyro in a Jobo - better results on occasion after trying everything suggested in previous threads on the topic (aside from nitrogen) - but 'on occasion' = useless

I've given up, gone back to tray and convinced myself it's both meditative and character building
 
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