Quote Originally Posted by Cheryl Jacobs
OK, looks like I need to give a bit more information....

The film is 220. It was processed in a small tank, just the one roll by itself. It was loaded onto a plastic reel (the kind with the ball bearings) and I didn't notice any catches in the film as it wound. Seemed fine. I'm 100% certain there was enough developer in the tank, because I measure very carefully and know exactly how much fits into it.
Oh ... well, in that case ... It might have been tribo- or sono- luminescese, or, or .... uh ... did lightning happen to strike the tank? .... or ... or...

I'm reduced to only one thing left ... the "safety valve" for all processing problems ... Must've been defective film ... Yeh, that's it ...

Back to reality: Damned if I know.

When you speak of "horizontal" banding, do you mean "at right angles to the long edge of the complete roll"?