Re: SP445 film holder marks on negatives ( how to do this intentionally )
How about you put the film in the holder with the emulsion facing the holder, then very briefly flash the arrangement to leave a barely visible exposure of the holder on the film. It would probably be most effective if you flash the set-up with light ;-)
Then turn the film around before you develop it so it will get proper development.
Re: SP445 film holder marks on negatives ( how to do this intentionally )
Thanks for this tip. Would never have thought.