Barrel & Grit field manual
Rock tumbling stages and schedule: when to move to the next grit
A rock tumbling schedule is a sequence of inspections, not four automatic timer settings. Learn what each stage must accomplish before the stones advance.
Stage 1: coarse shaping
Run fresh coarse silicon carbide until unwanted pits, cracks and sharp edges are removed. Check about weekly in a rotary tumbler; difficult rough may need several charges.
Stage 2: medium smoothing
Medium grit removes the deep scratches left by shaping. Clean the barrel, lid groove, stones and media before loading, and return visibly defective stones to coarse.
Stage 3: fine or pre-polish
Fine grit prepares an evenly smooth surface. Dry several stones under bright light: scratches, frosted edges or fresh cracks mean the batch is not ready for polish.
Stage 4: final polish
Use a proven final polish that suits the material and keep it isolated from coarse abrasive. A common rotary starting schedule is about seven days, but inspect the finish rather than obeying the date.
Track each barrel
Record the rock type, loaded weight, media, abrasive, start date and inspection result. The free Workshop batch tracker keeps multiple barrels on separate schedules.