1500 Grit Silicon Carbide Rock Polishing Grit 20lb - Stage 4 Finish

In this review the 20lb bag of 1500 grit silicon carbide from MJR Tumblers is judged primarily on polishing performance and value for hobbyists and small shop users. The package is aimed at those who need a robust fourth-stage abrasive for shaping and refining lake glass, sea glass, and smaller stones; the biggest reason to buy is the consistent, coarse-but-refining texture that works in both rotary and vibratory setups and holds up well during normal runs. The fact that MJR Tumblers is a Disabled and Veteran Owned Company based in Pecatonica, Illinois, is noted by customers and reinforces the American-made appeal.

Key Features

• Premium quality: The 1500 grit silicon carbide delivers a predictable abrasive action that helps move pieces into the final shaping stage without over-smoothing too early.
• Universal compatibility: Formulated to work with any brand of rock tumbler, so it fits existing kits and barrels without modification.
• Stage-specific grit: Designed for the fourth stage of tumbling to refine surfaces before final polish, giving better control over the final texture.
• Value-sized packaging: The 20lb quantity provides multiple batches worth of material, reducing per-batch cost for frequent tumblers or small shops.
• American owned: Manufactured and sold by an American company in Pecatonica, IL, which appeals to buyers seeking domestically supplied abrasives.

Who It's For

This product is best for hobbyists, lapidary beginners, and small workshop users who run multiple tumbling batches and need a dependable fourth-stage abrasive. It suits those polishing lake glass, sea glass, and a variety of common tumbling stones where a coarse-to-medium polishing step is required before final polish.

It is less suitable for users who expect immediate high-gloss results without a final polishing compound, or for those working exclusively with very soft minerals that require gentler, non-silicon-carbide media. Professionals seeking specialized micron-rated polishing pastes should look elsewhere.

Pros & Cons

Pros

• Good polishing ability for stage 4 shaping, improving surface uniformity before final polish.
• Strong value for money in a 20lb bag that covers many batches.
• Works well in both rotary and vibratory tumblers due to its rough but consistent texture.

Cons

• Some users report limited shine without an additional final polish, so a separate polishing compound may still be needed.
• A few customers noted the grit can break down sooner than expected in very long runs, affecting longevity in some setups.

Specifications

Our Verdict

The 20lb 1500 grit silicon carbide bag is a sensible buy for hobbyists and small shops who need a reliable stage-4 abrasive that balances cutting action and preparation for final polish. It offers strong value and broad compatibility, though those seeking instant mirror shine will still need a separate polishing step. Overall, it is a practical, American-made option for regular tumbling work.

Frequently Asked Questions

Will this work in vibratory tumblers?
Yes, the rough texture of the 1500 silicon carbide is reported to perform well in vibratory as well as rotary tumblers.

Is this grit ready to produce a high gloss finish?
No, this is a stage-4 shaping grit; most users follow with a dedicated polishing compound for final high-gloss results.

How much does 20lb cover?
Coverage varies by batch size and rock volume, but 20lb provides multiple full batches for typical hobbyist tumblers and reduces per-batch cost.