Vertical streaks on C41 negatives

Hello all, I'm back ...again...with more frustrating issues. I'm getting these vertical streaks on my negatives and it seems to only really be happening on 120 film. I've taken my developed negatives to a local lab that uses a Noritsu scanner to see if It's my scanning method or my developing process. The scans came back with the same results so I'm certain it's a developing issue. My entire process is as follows:

Current medium format camera:

Yashica D with Yashikor 3.5 lenses. Mint condition.

Film used all having same streaking issues:

Ektar 100, Portra 400, Fujipro 400H

Film is NOT expired and stored in my mini fridge. Warmed up before loading camera.

Chemicals:

Unicolor C41 powder kit.

Mixed with distilled water at 110 degrees F. Temperature brought down and maintained at 102F for processing.

Tank:

Paterson tank and reels. Used for about 4 months. Cleaned very well after each use. In great condition, never have a problem loading reels.

Develop Process / Agitation methods:

Chemicals are stored in cleaned out plastic soda bottles away from light and in my mini fridge. I place the chemicals in a water bath with the temp maintained at 102 degrees by a sous-vide machine. I've tried a pre-soak in the past, and now do not pre-soak. Either way results have been the same. I pour in the developer and lightly stick agitate for the first 10 seconds, followed by 4 GENTLE inversions every 30 seconds there after for 3.5 minutes. In the past I've done all stick method agitations, and still see same results. After developer, I pour in blix, same agitations as developer but for 6.5 minutes. Follow this up with a rinse for about 3.5 minutes in ~100F tap waterer. I then follow this up with a 45 second room temp stabilizer and distilled water mix . Negatives are pulled and a one time gentle squeegee using two damp clean fingers. Hang dry in shower.

Scanning method:

Fuji XT2 with Canon FD 50mm 3.5 macro lens. Bright light table which I diffused and I raise the film slightly off the table to make sure I don't get any of the pixels from said light table. Convert negatives inside LR using Negative Lab Pro. I make sure to block out any excess light which my come over the top of the negative. I used to have problems with this but have gotten better.

Here is an example shot on Kodak Ektar 100 rated at 50. I dropped the exposure way down in post to exaggerate the streaks so you can see them easier. The second image is correct exposure in post so you can see it more faintly.

Correct exposure:

Here is an example shot on Fujipro 400H developed by myself and scanned at local lab using Noritsu scanner. The streaks are more faint in this shot for some reason, but still noticeable if you look closely.

Similar shot, different frame on the same roll, developed AND scanned by myself. Streaks still apparent but faint.

Three suggestions:

Ditch the Unicolor chemistry and use a decent brand like Tetenal. More expensive, yes, but cheaper than wasting film.

Get an accurate thermometer or calibrate the one you have. Cheap digital ones might give the impression of accuracy, by reading to a decimal fraction of a degree, but most of them are out by a degree or two.

Get a rotary processor and tank. A Jobo CPE-2 for example. Hand inversion processing isn't controllable enough for consistent results.

Also ensure that your Blix or bleach and fix are fresh. Those streaks are typical of under-bleached C-41. Or of scanning film before it's properly dried.

Chemicals are stored in cleaned out plastic soda bottles away from light and in my mini fridge.

Could be part of the problem. You should never store chemicals at low temperatures close to freezing. It can cause precipitation of some of the ingredients, which may not remix properly, even with a vigorous shaking.

Developing chemicals merely need storing in a dark place and well-sealed against oxidation (air). Your old pop bottles might not be properly airtight. Most cheap plastics are porous to gases.

Also ensure that your Blix or bleach and fix are fresh. Those streaks are typical of under-bleached C-41.

I concur that this seems likely. Especially since you mentioned "blix." Pro processing of C-41 generally uses separate bleach and fix because they're much more economical (in volume) and reliable. (Blix works fine for paper, just not so much for film, which needs much greater "strength.")

One of the standard tests for poor bleaching or fixing is to rebleach and refix, or in your case, reblix. Ideally you would do the test with known-good blix. But lacking this you can still probably test with what you have, given that it seems to have largely worked.

The best way to do the test is to find a junk frame that shows the problem. You cut this negative in half, then reblix one half. Wash and dry it, then view both halves together over a light table. If there is any change at all, this means that the original blix was inadequate. (In normal processing the bleach and fix steps are "complete" such that further bleach/fix has no further effect.)

The combined bleach and fix component tend tend to be mutually destructive over time, so probably best to use fairly soon (whatever that means) after mixing. Whereas separate bleach and fix can last a long time.

As a note, if you find that your film has been inadequately blixed, it can be redone (including rewash, etc.). Best of luck with it.

Three suggestions:

Ditch the Unicolor chemistry and use a decent brand like Tetenal. More expensive, yes, but cheaper than wasting film..

Thanks for the response and advice. I’ve been told before to try Tetenal but have been holding off because of price. But yah now I’m just wasting film so I’ll give it a shot. I’ll post back with some hopefully good results sometime soon.

I concur that this seems likely. Especially since you mentioned "blix." .. As a note, if you find that your film has been inadequately blixed, it can be redone (including rewash, etc.). Best of luck with it.

Thanks for the tips, Bill. I’ll give this a shot!

Chiming in on this, I've had similar results with Unicolor. I've tried Tetenal with great results. Cinestills liquid kit isn't bad either... but try Tetenal first.

Will do. Glad to hear more positive feedback for Tetenal.