The Complete Guide to Knife Finishing with Cratex Rubber Abrasives
You've ground the bevels. Heat treated the blade. Worked through your sandpaper progression. The knife is taking shape — but it doesn't look finished.
That last stretch — from a sanded blade to a polished, professional-looking knife — is where most makers either level up or settle for "good enough." And it's where Cratex rubber abrasives earn their place in the shop.
What Is Cratex?
Cratex is an American manufacturer of rubber-bonded abrasives based in San Diego. They've been making these products for over 70 years, and while their catalog serves dozens of industries — machining, gunsmithing, jewelry, electronics — they've become a staple in knife making shops because their products solve a very specific set of finishing problems.
The core idea is simple: premium-quality silicon carbide abrasive grains are embedded throughout a rubber matrix. As you use the tool, the rubber wears away and continuously exposes fresh, sharp abrasive grains. Unlike sandpaper, which dulls and clogs, a Cratex wheel or point performs consistently from the first touch to the last.
The rubber bond also provides a cushioned cutting action. This is critical for knife makers. A rigid abrasive — like a stone or a hard-bonded wheel — can dig into your blade and remove more material than intended. Cratex's flex means it polishes aggressively without gouging, even in areas with complex geometry like plunge lines and guard junctions.
Where Cratex Fits in the Knife Making Process
Cratex doesn't replace your belt grinder, and it's not your first sanding step. It's a finishing tool — the step between your sandpaper progression and your final buff or strop.
A typical workflow looks like this:
- Belt grinder — rough grinding, bevel shaping
- Sandpaper progression — 120, 220, 400 grit
- Heat treatment
- Post-HT sanding — clean up any heat-treat scale
- Cratex — fine grinding, scratch removal, polishing, detail work
- Final finish — compound and strop for mirror, or stop after Cratex for satin
The value of step 5 is that Cratex handles the work that's too fine for your belt grinder but too precise for sandpaper. Cleaning up a plunge line, polishing the junction between guard and blade, evening out a scratch pattern across the blade flat — these are tasks that require a tool with both precision and forgiveness.
The Products Knife Makers Use Most
Points are the most popular Cratex product among knife makers. Available in bullet and cylinder shapes, points mount on a Dremel or Foredom and let you work specific areas with surgical precision. Plunge line cleanup is the headline use case.
Small Wheels are for polishing blade flats, spine finishing, and evening out scratch patterns.
Cones are tapered shapes designed for inside curves and concave surfaces — finger guards, choil interiors, and sub-hilt designs.
Large Wheels mount on your bench grinder for broad-surface finishing across the entire blade length.
Blocks and Sticks are for hand finishing — direct, controlled contact without power tools.
The Grit System
Every Cratex product comes in four standard grits, color-coded for easy identification:
- Coarse (Green) — material removal, rust, deep scratches
- Medium (Dark Brown) — general smoothing, scratch removal, blending
- Fine (Reddish Brown) — refinement, pre-polish prep
- Extra Fine (Grey-Green) — final finish, polish prep
Most knife finishing starts at Medium or Fine. You only need Coarse for restoration work or heavy cleanup.
Tips for Getting Started
Start with points. If you buy one Cratex product, make it a set of points with mandrels. They solve the most common finishing frustration — plunge lines.
Invest in extra mandrels. Keeping multiple mandrels loaded with different grits eliminates swapping mid-session.
Light pressure, moderate speed. Let the abrasive do the cutting. Pushing hard defeats the cushioned action.
Dress your shapes. Cratex points and cones can be reshaped against a sharp file to match your exact blade geometry.
Whether you're ten knives into this craft or five hundred, the finish is what people notice first. Cratex is how you make it right.