I use ZAM on a felt wheel - never had any scratches-
Hello Rudolf, I polish after flash firing first with wet cerium oxide and a soft felt wheel on the polishing machine. Then I tumble the workpiece for about an hour with small stainless steel balls, conus and bolts of different dimensions and a teaspoon of curd soap shreds. The gloss is after that in my opinion perfect.
The advantage of tumbling is, that the silver surface get a bit harden.
Edmund