Cratex 101: Everything Knife Makers Need to Know
Cratex rubber-bonded abrasives have been a finishing shop staple for over 70 years. If you're a knife maker who's never used them — or if you've been using them for years and want to make sure you're getting the most out of them — this page covers everything from the basics to the pro techniques.
What Are Rubber-Bonded Abrasives?
Traditional abrasives (grinding wheels, sandpaper) hold their abrasive grains in a rigid bond — resin, ceramic, or paper. When the surface grains dull, the tool loses effectiveness. You replace it.
Cratex uses a different approach. The abrasive grains (premium silicon carbide) are embedded throughout a flexible rubber matrix. As you use the tool, the rubber wears away and exposes fresh, sharp grains underneath. The tool performs consistently from start to finish — no dull spots, no hot spots, no inconsistency.
The rubber bond also provides a cushioned cutting action. Instead of rigidly contacting the work surface (which can gouge, dig, or chatter), Cratex flexes slightly under pressure. This means it polishes aggressively without removing more material than intended — critical when you're working on a knife blade where geometry matters.
Grit Textures
| Grit | Color | Approx. Mesh | Use |
|---|---|---|---|
| Coarse | Green | ~54 | Material removal, rust, heavy cleanup |
| Medium | Dark Brown | ~80 | General smoothing, blending, scratch removal |
| Fine | Reddish Brown | ~150 | Refinement, pre-polish |
| Extra Fine | Grey-Green | ~240 | Final finish, polish prep |
Full Grit Guide for Knife Makers →
Product Shapes Reference
Small Wheels (3/8" to 1" diameter)
Mount on rotary tools. Available in straight-edge (flat surfaces) and tapered-edge (getting into transitions). Best for blade polishing, spine finishing, and accessible flat areas.
Large Wheels (1½" to 6" diameter)
Mount on bench grinders. Best for full-blade polishing, restoration, and long blades where small wheels would take forever.
Points — Bullet Shape
Mount on rotary tools. Rounded tip follows concave curves. Best for plunge lines, choils, inside curves, and concave transitions.
Points — Cylinder Shape
Mount on rotary tools. Flat contact surface. Best for flat plunge lines, ricasso finishing, and bolster faces.
Cones
Mount on rotary tools. Tapered profile follows concave geometry. Best for finger guards, inside curves on sub-hilts, recessed areas around pins and fasteners.
Blocks (Rectangular)
Hand use — no tools needed. Flat contact for controlled finishing. Best for blade flats, handle scales, restoration, and any work requiring maximum control.
Sticks (Round or Square, 6" long)
Hand use. Best for reaching into fullers (blood grooves), channels, and narrow recessed areas.
Tool Compatibility
| Product | Dremel | Foredom | Bench Grinder | Hand |
|---|---|---|---|---|
| Small Wheels | ✓ | ✓ | — | — |
| Large Wheels | — | — | ✓ | — |
| Points | ✓ | ✓ | — | — |
| Cones | ✓ | ✓ | — | — |
| Blocks | — | — | — | ✓ |
| Sticks | — | — | — | ✓ |
All rotary-mounted products require mandrels (sold separately).
Speed and Pressure Guidelines
Speed: 10,000–15,000 RPM for most rotary tool work. Lower speed = finer finish with more control. Higher speed = faster cutting but more heat and less precision.
Pressure: Light. Let the abrasive cut. Pushing hard defeats the cushioned action, generates heat, and wears the product faster without improving the finish.
Direction: For blade flats, work parallel to the edge for a traditional satin look. On curved surfaces, follow the contour.
Pro Techniques
Custom shaping: Dress Cratex points, cones, and small wheels against a sharp file to create custom contours that match your exact blade geometry.
Stacking wheels: Mount multiple small wheels on a single mandrel for a wider contact surface on broad blade flats.
Speed variation: Start a pass at moderate speed for material removal, then slow down as you approach the final surface. The slower pass leaves a finer finish.
Between-grit cleaning: Wipe your blade with a clean cloth between grit changes. A single stray coarse grain on your extra fine surface will leave a scratch.
Also a Jeweler?
Everything on this page applies to jewelry finishing too — the same grits, the same shapes, the same self-renewing abrasive technology. The difference is your tools (flex shaft instead of bench grinder) and your materials (precious metals instead of blade steel).
We wrote a dedicated guide covering grit selection for gold, silver, and platinum, plus the specific Cratex shapes that work best on rings, bezels, and castings.