Hello JOHN P.
I've been tumbling my things since 1992 or -93; that is: only
about 3 hours for each tumbling (ho-ho). I use a Lortone barrel
tumbler, a mix of shots and started with expensive burnishing
soaps. An old jeweller learned me the trick to use a fat, rich
liquid soap, about a spoonfull for each tumbling, and topped up
with normal tap water. If I can empty the barrel immediately
after tumbling, I add about a teaspoonfull of ammonium hydroxide
(NH4OH). It works very well for me.
Niels, from springtime Denmark