After pickling gold & silver you end up with a white fire scale on the metal. In the past I would tumble with 2 type of abrasive plastic pyramids & Steel shot in 3 steps, and it took about 6 hours. I figured out if I got a steel or brass wheel for my Dremal or Flex Shaft. Taped a little white diamond prepolish on it while spinning & work your piece like your polishing, it usually takes less than a minute, then polish as usual. It doesn’t get into deep holes & crevasses, but does a far superior job (in my opinion) than the tumble barnisher & MUCH quicker. It doesn’t do as good a job on gold as bombing, but that’s dangerous.