Gelatin supplies 2 important functions in emulsion making. Gelatin functions as a peptizing agent and as a vehicle.
As a peptizer, it prevents silver halide from falling to the bottom of your beaker in one lump or a few large lumps. Instead, gelatin suspends the crystals in a creamy mixture.
As a vehicle, it supplies a viscous "melt" that can be coated and hardened and which remains intact through the processing procedure. It must be transparent and colorless.
If you select a material for emulsion making it must do all of the above. At EK we never found a single polymer that could do all of the above. We found two families of polymers that supplied the features of a peptizing agent and as a vehicle individually. That is about it.
Bill has had some success with the Silanes. I hope this is of use to all of us.
Yes, but in terms of image aesthetics is it really necessary. Salt prints, Van Dyke and Platinum don't need it.