Recently I had read something (on here?) about ultrasonic cleaning of cases. After looking around at several ultrasonic cleaners, I thought of using my tumbler. Ultrasonic cleaning is just vibrations, right? So I would have to leave it in longer, no biggy. Anyway.... here are my results. 1 cup of white vinegar to 1/2 quart of water. "tumbled" for about an hour, rinsed, dried and cut open for inspection. The one on the left is tumbled in walnut media.