Help with C-41 streaking on negatives

Hello!

I work at a community college in a photo lab as a paraprofessional. I’ve been going to this school for about 2 years before working here and there has been an ongoing problem with developing C-41 film. Students have complained several times about streaking, weird chemical artifacts, etc on their negatives. I’ve also experienced these issues a couple of times myself. We use Fujifilm chemistry (I’ll list the exact chemistry at the end), The Jobo CPE3 Lift and Jobo tanks/reels.

After doing some research and finding some threads that suggested I just recently tried telling students to add a prewet at dev temp (100 degrees Fahrenheit) I thought this to resolve the issue but then another student complained about streaking. Does anyone have any expertise or helpful hints to share (or anywhere else I could inquire about this)

I also included images of students negatives and scans to help identify issues.

Fujifilm chemicals we use:

Fujifilm NEG N1-S Developer Starter

Fujifilm CN-16 MV Developer Replenisher

Fujifilm CN-16L N2-R Bleach Replenisher

Neg RA N3-R Fixer & Replenisher

Neg N4-R Rinse Plus & Replenisher

When you take pictures of a monitor with a phone it's creating additional aberrations that make it hard to isolate the developing problem.

loccdor said:

When you take pictures of a monitor with a phone it's creating additional aberrations that make it hard to isolate the developing problem.

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Good point, I will try to get ahold of some of the affected negatives and scan them.

Gabe said:

Good point, I will try to get ahold of some of the affected negatives and scan them.

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No - use another source for the backlighting.
Taped to a window with a featureless and out of focus background works.

MattKing said:

No - use another source for the backlighting.
Taped to a window with a featureless and out of focus background works.

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Okay sounds good, hopefully I can get ahold of some of the negatives tomorrow. I will post pictures when I do.

This resource may help as well: https://www.photrio.com/forum/resou...nsparencies-for-troubleshooting-purposes.461/

Window light is great, no AC light tables.

First thing, won't hurt anything, is extend fixing times, double check the fixer.

I've use/used every Jobo machine over the years. Never had a problem with streaking. I'm in my own darkroom, chemicals always fresh, no contamination. Doesn't mean I don't screw up, but I can usually see what I've done wrong.

A couple years ago I blanked out adding starter when mixing (working) tank solution of RA-4 developer, I must have wasted 8 hours before I realized.... oh crap!!!!

Best Regards Mike

Gabe said:

Does anyone have any expertise or helpful hints to share (or anywhere else I could inquire about this)

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Do you use a stop bath? If not, start doing so. Acetic acid is OK. 0.5%-1% concentration is OK for single use.
If the streaking persists, I'd try a run where you don't use the Jobo lift for filling & draining the developer. There's two possible issues related to the lift:
1: Contamination of the tubing. This can result in the kind of streaking you're seeing here.
2: Too slow fill & drain times. Manual filling & draining can be done more quickly.

It always helps in cases like these if you describe in detail your process. There's many ways to do this and it's the subtle variations that often bring about problems - as well as solutions.

PS: the pre-soak is a good idea. I always use one with a Jobo processor and film formats larger than 135. On those formats, I have often seen surge marks; they're totally different than the problem you're showing here, but also annoying/unacceptable, and for me at least, the pre-soak helps to avoid it for the most part.