How long does it take for each grit cycle to polish stones effectively?
Suggested tumble times are as follows: Grit #1: 3–5 days, Grit #2: 6–8 days, Grit #3: 6–8 days, Grit #4: 7–10 days. Longer cycles generally yield better results (Page 3)
From the official National Geographic Rock Tumbler Kit Instructions manual, page 3
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