Quote Originally Posted by Photo Engineer View Post
...,but two layers often act as if they have a huge partially reflective mirror between them.

PE,

Assuming that any reflection issues inbetween layers are due to surface tension, I further assume that coating those layers simultaneously in contrast to coating them in several runs would yield different effects. Actually, I expect simultaneously coated layers of identical gelatines (or rather RI) not to show any interface reflection at all.