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View Full Version : Damned streaks with C-41 on Jobo expert tank



SamReeves
9-Nov-2009, 19:56
Somehow the color film gods are pissing on my party with development streaks. I'm processing Kodak 4x5 Portra 160VC on a Jobo CPP-2. I am using a lift, I am using a Expert 3010 tank, and I'm over-filling by 20% to be on the safe side. I'm processing with an old motor at rotation speed 4 as recomended by Jobo, 5:00 warm up, and 3:15 development time at 100F. I've leveled off the tank twice, and despite all of it…the streaks just keep on coming. I'm at a loss for what's happening to my film.

Suggestions please?

largeformat apt
9-Nov-2009, 20:31
G'day,
See if you can go slower.
Pat

Robert Ley
10-Nov-2009, 15:39
I'm with Pat. I usually run my C-41 at between 3 and F. It is strange that you should get streaks at a setting of 4. Can you scan a neg and show us an example? Also, what kind of chemistry are you using?

Robert

Stephen Willard
11-Nov-2009, 08:17
If your drum is not level then you will get uneven development and streaks even if you use 20% more chemistry. It is not good enough to level the processor. You must level the drum in the processor with water in the drum to properly weight it. The cover must be on the drum such that there is very little wobble as the drum rotates in the processor before you can level the drum.

Through repeated tries, reinstall the cover on the drum until the drum rotates smoothly without wobble. Use a Sharpie permanent maker to trace/mark the position of the cover on the drum. Each time you install the cover on the drum make sure that the cover is aligned with the marker trace lines on the drum. This will insure the drum will rotate smoothly without wobble. Only after the cover on the drum is fitted properly can you level the drum in the processor.

The level must be placed directly on the drum surface and not on any of the drum ribs or cover. To do this I have found a small steel level that I put small round magnets of equal thickness on the ends of the level. I can then slide these magnets along the edge of the level so that I adjust their position so that they set directly on the drum surface. This configuration elevates the level so that it does not come in contact with the cover or ribs of the drum.

Please note, each drum type such 3010, 30005, or 3006 all level differently and require different shims. I have made shims for each of these types of drums so when I switch drum types I also switch to the corresponding shims.

Hope this helps...

SamReeves
11-Nov-2009, 13:12
Got it. Thanks guys.

I'm using Tetenal's C-41 5L kit. Which has done pretty well for me in the past, but maybe the developer is a little old. I haven't used it since the summer.

I'll also do a rotation test to see how many I'm getting at speed 4 as opposed to speed 3.