Quote Originally Posted by Dr Croubie View Post
thought the answer was that the circles and numbers were coming off the backing paper
[...]
Or maybe It's just a QC problem, a bad batch? For people who have had the problem and then haven't, was it all film bought at once?
I have had good and bad luck with the Shanghai film, but I like it when it is good.

What decided the backing paper print-through came from was poor ink on the paper affecting the emulsion. This assumes your "red window" isn't an issue, which was on an old Brownie I have. Black gaffer tape fixes that.

Obviously this isn't ever a problem with the sheet film.

The decision that it was the ink interacting with the emulsion - and I could be completely wrong - made me realize just how complex a boutique film plant would be to produce small runs of high quality film. The number of things that have to be "right" to make a first rate film is mind-numbing. OTOH it is completely possible to pour your own plates in your own darkroom.