Another way I neglected to mention for the Newton ring stuff is of course wet-mounting the negative, but I just didn't want to go there. I have no interest in doing anything like that.

I'm a notoriously paranoid perfectionist always thinking about ways to make things better, and tend to occasionally get sidetracked from actual photography into these experimental/technical rat holes. I think this particular one is over for me. Although I'll continue to be interested in any glass coating someone finds that prevents Newton rings, for now I'm done with this particular bit of insanity.

I don't think you have any explaining to do. Tice, Ansel etc - no coated carrier glass.