Ok, let us use an example of Plant X (UNNAMED BUT REAL) making film. They use a trough or dip coater at speeds of about 10 - 100 ft /min. IDK how many troughs they have in the coating train. They use open air festoon drying! This is about 1920 style production. This real facility is in operation only when the weather is acceptable for manufacturing film, as they have no air conditioning or drying capability. So, it can't be too hot, cold or wet!
I have posted an example of their film here previously which I am reposting here. This is a sample of film from a trough coater. It is typical of the result which gives a sinusoidal pattern to the coating. In addition, festoon drying introduces a defect at the point where the header racks are positioned at the ceiling. Therefore if you have a 40 ft ceiling, then the longest roll of film is either 40 ft (if you use bottom racks) or 80 ft if you use gravity to hold the festoon in place (not a good idea but possible). This limits you to making amateur roll films and prohibits motion picture film production due to length restrictions. Well, the sinusoidal density patterns will give you a nauseating headache on screen projections too.
This is probably why some old motion pictures show light/dark variations in a regular pattern.
Scuff marks or cinch marks will be random over the surface of the film and cannot be detected easily without a sophisticated system. In fact, I would be surprised if the bulk of them can even be detected. This is worse with coarse grain, low gelatin coatings as the grains actually stick up as bumps on the surface of the coating and cinching causes streaks and foggy spots.
To continue, the new hardeners are so toxic and so quick acting that they cannot be used in a trough coater, as the fumes would harm the lead coater, and the trough would set up within a few seconds of being filled.
So, I've enumerated possible problems and actual problems at one potential supplier of film your film if Kodak, Ilford or Fuji goes under.
Now, to fix these there would need to be a huge capital investment that would add drying cabinets, hepa filters, undercut roller transport, multiple extrusion or a single slide hopper front end, containment and handling of a new hardener and that would bring the facility up to producing a modern film, or at least reduce the defects inherent in their current production. Of course this also would require an upgrade in the pumping system and the film transport system to eliminate that pattern in the attached scan.
The engineers at Plant X are amazing people to make what they do with the equipment they have, so I stand in awe at their ability, but I do have to show you the flaws as suggested by HRST. You guys are buying this film. You guys complain on-line about defects constantly.
Kodak, Ilford and Fuji are committed to quality products. That is all I can add. Now, as for color, multiply everything by about 10x just for starters (but it is more like 100 - 1000x probably).
PE