Answering a few questions here:
1. Yes it is a potato ricer. I thought I had mentioned that. Sorry. At Kodak we used heavy duty versions.
2. The posted URL shows the coating of a solvent. Silver halide in gelatin cannot be coated so triivally I assure you. It is much more viscouse. Also it takes several hours to dry. You should not use a hair dryer! It will blow the wet gelatin around and create puddles.
3. In hand coating emulsion does run across the back. This is seen if you look at the posted photos carefully. This is how you know you have an authentic hand made plate. The defects like that prove it.
4. Mark is a world reknown authority on this method! Do not confuse it with wet or dry plate collodion which are totally different. Mark does those too.