Read the abrasive, not only the stage number
Silicon carbide is a common grinding abrasive because its hard, angular particles cut the tumbling rough. RockTumbler.com gives examples including 60/90 coarse, 150/220 medium, and 500 fine, followed by a separate polishing compound. These are examples from its process, not a promise that every kit uses the same grades.
Build your own four-column supply record: container name, abrasive material, grade, and assigned step. If a label says only “Step 3,” retain the supplier instructions with it. Ask the supplier what the packet contains before replacing it with a loose powder carrying a different description.
Coarse: choose the shape you are willing to keep
The first question is whether you like the outline and major surface features. Mark a photograph of the edges or pits you want to change, then compare it at inspection. If the stone already has the shape you want but an isolated defect remains, decide whether removing more material is worth the change in size.
Bigger abrasive is not automatically a better shortcut. In a published small-tumbler experiment, RockTumbler.com found 60/90 more effective than the extra-coarse grades it compared. That result applies to its test conditions; it is a good reason to use a supported recipe before experimenting with unusually coarse grit.
Medium and fine: check the whole surface
Use separate photographs for overall shape and surface condition. The first shows whether the stone is becoming the form you want. The second should show whether its finish looks consistent. Examine recesses and the less attractive side as well as the face you naturally notice first.
Write a specific checkpoint such as “inspect the shallow indentation on the gray side.” This is more useful than “looks better.” If a patch still differs from the surrounding surface, keep the observation attached to that stone rather than declaring the entire batch ready from one attractive example.
Polish: finish a prepared surface
A genuine lapidary polishing compound is a distinct supply choice. RockTumbler.com lists aluminum oxide, cerium oxide, tin oxide, and other compounds used for this purpose. Its guidance also stresses that technique can matter as much as which compound an operator prefers.
Before changing the polish, verify that you used the intended product, prepared the stones through the earlier steps, and kept the finishing setup clean. Change one variable in a future comparison and document it. Replacing several materials at once leaves you unable to explain why the result changed.
Questions at the workbench
Can I skip a grit stage?
Use the full supplier-supported sequence while learning. An experienced operator’s shortened recipe may depend on particular rough, abrasives, and equipment. Record a successful baseline before attempting a controlled change.
Does a higher grit number always mean final polish?
No. Read the material and intended use as well as its grade. A container described as fine grinding or pre-polish should not be assumed equivalent to the final polishing compound in another supplier’s recipe.
Sources & further reading
- RockTumbler.com: What is silicon carbide grit?
- RockTumbler.com: Extra-coarse grit experiment
- RockTumbler.com: Choosing a polishing compound
Machine instructions take precedence for its loading, materials, operation, and maintenance. Send a correction.
