In the context of holography there has been some research on polarization issues related to gelatin. Under certain
Originally Posted by AgX
circumstances one might get fairly large differences between p and s-polarization.
Having said that, refractive index remains the key parameter regarding internal reflections. The degree of internal reflection may also depend on wavelength...
The reason for this I only can speculate on. It could be mechanical tension. Though I expect this would not be established in case of wet/wet coating of similar gelatine solutions.
Maybe processing (development-fixing) involves significant refractive index changes. Has there ever been research on this subject?
However, even in this case there would be an interface. In the form of a layer of wetting substances.
I guess the wetting substances (being essentially hydrophilic) would get fully absorbed by the gelatin-water layer to be coated on top of it.