Jewelry Polishing

I have two queries on jewelry polishing. 1. In a magnetic polisher what grade of stainless pins are used - 304, 316 etc. Do they need to be inherently magnetic or is the magnetism induced by the polisher? 2. In vibratory polishing of jewelry I have been recommended stainless steel 420 but on using these I have found that the media is catching rust. Is this normal or should SS 420 be rust resistant. I had earlier used SS 304 - this was rust resistant. Any information on the above two points would be really helpful. Thanks. Achal.

Archal All stainless steel used in the making of media for magnetic systems starts out as drawn stainless steel wire. During this drawing process, the molecular structure gets re-arranged somewhat and therefore becomes magnetic. That means that almost all grades of stainless can be used to make media. The 300 series is the most common. I am not sure about the 400 series in regards to oxidation, but even the 300 series produces a good amount of dark carbon like residue during the processing of jewelry.