IMPACT-EVIDENCE MAP
Separate new bruising from old fractures before reworking
| Decision check | Evidence to collect | Bounded outcome |
|---|---|---|
| When did the mark appear? | Match the same edge across starting and stage photographs. | If the timing is unknown, describe the mark without assigning it to the tumbler. |
| Where is damage concentrated? | Map white crescents, chips, and fractures on exposed edges versus one pre-existing weak plane. | Edge concentration sends the load to an impact review; one fracture may require separating that stone. |
| What changed in the load? | Record fill, weight where required, size mixture, removed stones, media identity/history, machine, and setting. | Correct only a supported mismatch; do not invent a universal fill, speed, or media dose. |
| Is material removal acceptable? | Write the desired outline and mark features worth preserving before rework. | Hold keepsakes or specimens when grinding away damage would destroy the feature you value. |
Bruising / chip batch record
Batch, machine, barrel / bowl, and exact instructions: ________________________
Material and size groups: _________________________________________________
Before / after photo filenames: __________________________________________
New marks: □ white edge □ chip □ fracture □ none proven □ unknown timing
Load evidence: fill __________ weight if specified __________ media / history __________
Setting and source: _______________________________________________________
Preserve / rework decision and acceptable shape change: ______________________
One supported correction before next inspection: ____________________________
No entries are stored. Media and settings remain material-, stage-, and machine-specific; this record does not prescribe a universal amount.
Identify what changed and when
Compare photographs from before tumbling and after each stage. Mark the position of new damage on a copy of the image. If you have no earlier photograph, describe the mark without claiming the tumbler created it. The difference matters when you decide whether changing the load is likely to help.
Separate a missing chip from a pale line, a rough indentation, or a natural color boundary. Check several stones. Damage concentrated on exposed edges suggests a different investigation from one stone breaking along an obvious pre-existing fracture.
Hardness does not remove the need for material-specific handling
RockTumbler.com’s obsidian instructions describe impact-related bruising and the use of suitable ceramic material to reduce harsh stone-to-stone contact. Its banded-amethyst example documents edge bruising and cushioning for that exact 1/2–2-inch rough. These are reasons to use material-specific guidance rather than treating every hard-looking stone like durable jasper.
Make a separate plan for fragile or unfamiliar rough. Identify the material, find a relevant process, and keep the first trial small enough to inspect thoughtfully within an appropriate load. Do not add a prized specimen merely because another stone in the batch has a similar color.
Review the complete load before changing time
Compare the actual fill, required weight check, and rock-size mixture with the selected instructions. Note whether the load became smaller after stones were removed or ground down. Record the media identity, condition, and previous stage rather than writing only “added media.”
For adjustable machines, compare the setting with the exact manufacturer’s guidance. The Highland Park RT6.0 manual warns that excessive speed can damage stones; that does not establish a safe universal speed for other machines. Keep the machine’s identity attached to any setting in your records.
Decide whether reworking is worth it
Before another grinding run, write down the outcome you want. Removing visible damage may change the outline or size, and the decision may differ between a keepsake and ordinary practice material. Set aside stones you prefer to preserve in their current form.
If you proceed with a supported rework process, change the suspected problem in the setup and document the change. Compare the same marked edges at the next inspection. If fresh damage continues, pause and seek advice using the batch history rather than extending the run and hoping the finish catches up.
Questions at the workbench
Can polish remove a chipped edge?
A finishing compound should not be treated as a repair for missing material. First decide whether you want to reshape the stone and identify why the damage occurred, then choose a supported process for that material.
Should I add more ceramic media to every batch?
No fixed amount suits every material and stage. Review the complete load and material-specific instructions. Media is a tool for a particular purpose, and its suitability and preparation still matter.
Sources & further reading
- RockTumbler.com: Obsidian and Apache tears tumbling method
- RockTumbler.com: Before-and-after tumbling observations
- RockTumbler.com: Banded amethyst edge bruising and cushioning example
- Highland Park: RT6.0 owner’s manual, hosted by Flatlap
Machine instructions take precedence for its loading, materials, operation, and maintenance. Send a correction.