What Stones Can I Tumble?
I avoid tumbling turquoise and pearls. Pearls can have their nacre damaged, and turquoise, being porous, might absorb liquid. I always tumble the chain before adding these stones.
Amber has worked fine for me, but I only tumbled it for about 20 minutes.
Glass and Swarovski crystals have also been safe. Harder stones like quartz and chalcedony seem to handle tumbling well.
If I'm unsure, I tumble one bead first as a test threaded onto scrap wire to prevent tiny steel balls from getting stuck inside.
How Long?
I usually tumble small batches to suit my workflow.
I check pieces after 30 40 minutes and add more time if needed. The total tumbling time depends on both the material and the volume you're working with.
How Do I Store It?
After tumbling, I rinse the barrel and the stainless steel shot.
Then I cover the shot with filtered water about an inch above the shot and keep it stored in the barrel, upright, with the lid tightened.
I don't dry the shot, and I've had no problems using the same batch for over 2 years.