I have posted pictures here made by Mark Osterman of George Eastman House. He gave me the series as a demo on how to coat glass plates for use of the APUG members wanting to do this. I also recommend the use of a small amount of alcohol (everclear) to assist in even spreading, or the use of a surfactant to help even spreading. Chrome Alum is recommended as a hardener to assist in making the gelatin adhere to the glass.