10lb MJR Tumblers 400/600 Grit Aluminum Oxide - Third Stage Polish

In this review of the 10lb MJR Tumblers 400/600 grit aluminum oxide, the bottom line is simple: this bag is intended for hobbyists and small-shop users who need a dedicated third-stage shaping and pre-polish abrasive that works across brands. The reviewer found it useful as a refill for the stage 3 shaping step, delivering consistent abrasive action and predictable particle size for preparing stones before final polish. For those who want an American-made product from a disabled and veteran owned company, this grit is a straightforward, no-frills option.

Key Features

• Premium Quality 400/600 Grit: Provides a reliable abrasive for the third stage that helps shape facets and smooth surface scratches before final polishing.
• Compatible with Any Tumbler: Works with most rotary and vibratory tumblers, so users can replace stage 3 media without changing equipment.
• Large 10 lb Quantity: A sizable bag reduces the need for frequent repurchases for hobbyists and small workshops.
• Aluminum Oxide Abrasive: The chemical and physical toughness of aluminum oxide gives consistent wear characteristics across different types of stones.
• American Owned and Operated: Manufactured and sold by a disabled and veteran owned company in Pecatonica, IL, appealing to buyers who prioritize domestic sourcing.

Who It's For

This product is aimed at rock tumbling hobbyists, lapidary beginners and intermediate users who need a dependable third-stage shaping grit that is compatible with a variety of machines. If you maintain a regular tumbling workflow and prefer buying in bulk to save time and avoid frequent restocking, the 10 lb bag suits that use case well.

Those who should look elsewhere are professionals needing ultra-fine or industrially graded specialized abrasives beyond 400/600, or users who expect every batch to produce a high-gloss final polish without a separate polishing compound. This grit is for shaping and pre-polish rather than final shine.

Pros & Cons

Pros

• Consistent abrasive action that helps remove larger scratches and shape stones before polishing.
• Compatible with a wide range of tumblers, eliminating compatibility concerns between brands.
• Good value for a 10 lb supply for hobbyists who tumble regularly.
• Supports an American disabled and veteran owned company.

Cons

• Some users report variable final shine, so it may not replace a separate final polish step for glossy finishes.
• Not intended as a final polishing grit; an additional polish stage is often required for high-gloss results.

Specifications

Our Verdict

The 10 lb MJR Tumblers 400/600 grit aluminum oxide is a practical, American-made option for hobbyists and small workshops who need a reliable stage 3 shaping abrasive. It offers consistent performance and good bulk value, but users seeking a mirror-like finish should plan a separate final polishing step. Overall, it is a solid buy for its intended role and domestic provenance.

Frequently Asked Questions

Is this grit suitable for all tumblers?
Yes, it is formulated to be compatible with most rotary and vibratory tumblers from different brands.

Do I need an extra polish after using this grit?
Yes, this 400/600 grit is intended for shaping and pre-polish; a separate polish compound is recommended for high-gloss results.

Who makes this product?
It is produced and sold by MJR Tumblers, a disabled and veteran owned company located in Pecatonica, Illinois.