First, a disclaimer: I’m not a jeweler, but I do use a vibratory
tumbler to polish some decorative brass rings. So, this may not
apply to your case, but here’s what I’ve learned:
I get good results with a two step process: plastic media, then
As far as I know, the abrasive particles are distributed throughout
the plastic media, so you can use it indefinitely, but since it will
wear down to a smaller size you will need to add some fresh media
periodically to keep the volume up. Also, unless your tumbler
incorporates a through-flow of water, you need to rinse the gunk off
the media after every use (or perhaps even midway through the first
Hopefully your parts and media are “rolling” nicely when the tumbler
is operating–if you don’t have that top-to-bottom circulation then
it won’t work right. Sometimes the wrong mixture of water and soap
can cause a foamy gunk to adhere to everything–for this reason I
often wonder if dry tumbling might not be better for the first step.
The plastic media I use is a relatively fine grit, to allow going
straight to polishing in the second step.
After the first step I rinse and dry the pieces–I do that by hand,
but I would imagine an ultrasonic cleaner would be great for
You should have two barrels/bowls, one for coarse and one for fine
media to avoid contamination.
My second step after the plastic media is to tumble with dry media:
walnut shell fragments (available very cheaply as pet bedding) with
some dry aluminum oxide polish (not paste).
I run the tumbler for about 24 hours for each step.