braxus
From what you describe, it was motion picture film. That said, Seattle Film Works also sold regular C-41 color film under their brand. The trick is knowing how to tell the difference. Heres how. Pull the leader out and in a small spot on the emulsion side, scrape the emulsion off. I used my pocket knife. It is easy to do. Hold it up to the light, if were you scraped is clear or slightly pink, it is C-41 and can be safely processed C-41. If it is black or dark it is motion picture film. You are seeing the special anti-halation ramjet coating. Try it first on known C-41 unprocessed leaders so you know what to look for. We used this trick for many years and were able to process many rolls and look like heros too our customers. Then too, we knew which rolls to avoid. Remember, the customer is all ways right, but often doesn't know what they are talking about and sometimes will lie to you.
Michael