Select Stones by Hardness Compatibility
30 minutesChoose agate, jasper, quartz, or petrified wood of similar Mohs hardness; reject fractured or porous stones.
Beginner3-4 weeks
Rock Tumbling Project
Complete guide for rock tumbling project — step-by-step workflow, tools, checklist, and expert tips to get started.
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Workflow
Run Stage 1 Coarse Grind (60/90 grit)
7-10 daysFill barrel ⅔ full with stones, add grit per manufacturer ratio, cover with water; tumble 7–10 days checking daily seal.
Progress Through Medium, Fine, and Polish
3 weeksRinse stones and barrel thoroughly between stages; run 220 grit (7 days), 600 grit (7 days), polish compound (7 days).
Inspect, Sort, and Store Polished Stones
1 hourExamine under bright light for remaining scratches; re-run failed stones in fresh batch; store polished stones dry in divided tray.
Tools Used
- Time Duration CalculatorPrimary
Track tumbling duration for each grit stage to prevent over-tumbling that rounds stones to ovals.
- Mineral Hardness IdentifierPrimary
Verify all stones in batch share compatible Mohs hardness before loading barrel to prevent soft stone destruction.
- Rock Porosity CalculatorSupporting
Estimate stone porosity to predict grit retention in fractured specimens and adjust stage duration.
- Mohs to Vickers Hardness ConverterReference
Convert hardness values when mixing commercial grit recommendations with mineral hardness data.
Checklist
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Preparation
Technique
Quality
Maintenance
Reference Materials
Four-Stage Tumbling ScheduleTable
Standard grit progression for agate and jasper (rotary tumbler).
| Stage | Grit | Duration | Fill Level |
|---|---|---|---|
| 1 — Coarse | 60/90 silicon carbide | 7–10 days | ⅔ barrel + water |
| 2 — Medium | 220 silicon carbide | 7 days | Rinse completely |
| 3 — Fine | 600 silicon carbide | 7 days | Rinse completely |
| 4 — Polish | TXP or cerium oxide | 7 days | Add burnishing if dull |
Barrel Load RatioFormula
Optimal load = ⅔ barrel volume in stones + 1 tbsp grit per lb stones + water to just cover.
Cross-ContaminationStandard
One leftover coarse grit crystal in polish stage ruins batch — dedicated rinse bucket and barrel inspection between every stage.
Hardness Match
One soft stone in hard batch becomes mud — sort ruthlessly before loading.
Clean Between Stages
Obsessive rinsing between grits separates success from scratched polish.
Slurry Mess
Open barrel only in sink — silicon carbide slurry stains permanently.
Safety Notes
- Tumbler barrels leak abrasive slurry — operate on waterproof surface away from food prep areas.
- Silica dust from dried slurry is hazardous — wet cleanup only, never sweep dry grit.