Banding in colour negatives

[JohnsonWisconsin]

Hey all,

We run a rack and tank machine and have noticed lines forming across all film types, but most notably in cheaper emulsions (for example Polaroid One Shot Disposables).

Digitally, it appears in any scanner we use (we've 3 to choose from here). Physically, these lines appear on the emulsion side of the negative.

We've tried using 3 different chemistry types to date — Kodak Flexicolor, Champion Photochemsitry and most recently Fuji CN16.

We filter all of our water, use nitrogen to agitate and have several wash baths all at 37.9 degrees between fixing and wash.

Curious if anyone else has experienced or has knowledge with this issue, thanks.

 

[koraks]

Welcome to Photrio @JohnsonWisconsin !
This must be a very frustrating issue indeed. While I have very little experience with these kinds of processing lines, there are two issues that come to mind, especially given the severely warped snippet of film you show above:
1: Excessive pull force on the film.
2: Excessive heat in the drying unit/gallery.
A combination of the above is also conceivable, although a single cause is more likely.

I'd be tempted to inspect the various rollers in the path (which will take a while...) and see which ones have a striated pattern with the same pitch as the defect you get on your film. This may give a clue where in the path the problem may be occurring.

 

[lamerko]

...
2: Excessive heat in the drying unit/gallery.

Many years ago I got something similar while trying to blow out film with a hair dryer (don't ask why )

 

[Kino]

Certainly looks like a drying/tension issue.

Have you determined the absolute minimum temperature and air volume to dry the film?

Have you inspected the racks to insure all rollers turn freely?

In the last image, the film looks like fried bacon; the base is severely distorted. I would suspect the drying box/chamber needs another look to assure it's not too hot and that rollers are not dragging somewhere...

 

[foc]

What temperature is your dryer operating at?
How long does it take for the film to dry?
Is it hot air blown by a fan in the drying chamber?
If so is the air filtered and has the filter been cleaned?

All details about your film drying would be much appreciated.

 

[Sirius Glass]

Welcome to Photrio. The 35mm film shows signs of heat damage, so I would suspect that something is heating the film too much.