First you need to remove surface imperfections. Deep or heavy
scratches need to be removed by hand. Then you would use an
abrasive media - little plastic pyramids or cones, with a liquid
descaler - more than a soap, it contains surfacants, and is the
right ph for the media - in a vibratory tumbler. My preference is
for a flow-thru system to keep the junk out of the tumbler. If you
choose to use a closed system, you need to check and possibly
replace the liquid every couple of hours.
Removing surface imperfections can take several steps, using
decreasingly abrasive media, especially if you are cleaning
castings. For my fabricated work, I can make do with a single step.
Then to make the pieces shiny, you need a burnishing step. That is
usually done with stainless steel in a rotary tumbler, with a
burnishing liquid, again more than soap. Alternately, you can
burnish or polish with ceramic beads in a vibratory tumbler. Or if
you have lots of time, you can put your smoothed work in a mixture
of wood chips or shell bits, that have been charged with some kind
of polishing compound - chrome oxide or simichrome or rouge in a dry
system vibratory tumbler.
So to answer your questions - I use both kinds of tumblers, and
seldom hand polish at all. I finish my work in the tumblers, then
set stones as a last step.
I wrote a little book on the processes called “Tumble Finishing for
handmade jewelry”, available from Rio Grande or Frei and Borel. It
gives you details on what works and why and a cookbook chart on
where to start with media, times, etc. It might be useful to answer
your questions in more detail.
Judy Hoch, G.G. @Judy_Hoch www.marstal.com