How to Achieve a Mirror Finish on a Knife Blade
A mirror finish is equal parts patience, grit progression, and knowing when to move to the next step. There's no shortcut — but there is a system.
The Full Progression
Step 1: Sandpaper Progression (120 → 220 → 400 → 600)
This happens before Cratex. Your goal is a surface with no visible scratches to the naked eye at arm's length. Each sandpaper grit removes the scratch pattern from the last.
Step 2: Cratex Medium (Dark Brown)
Switch from sandpaper to Cratex. Use small wheels on your rotary tool for accessible surfaces and points for detail areas. Medium grit removes the fine sandpaper scratches and begins to unify the surface.
Work in one consistent direction on blade flats. Random orbital motions create cross-hatched scratches that show under high polish.
Step 3: Cratex Fine (Reddish Brown)
Same tools, next grit. Fine replaces the Medium scratch pattern with a finer one. The blade should start to show some reflectivity.
Check your work under a strong, raking light. Look for any remaining deeper scratches.
Step 4: Cratex Extra Fine (Grey-Green)
Your last Cratex step. The surface should now be uniformly smooth with no visible scratch pattern to the naked eye.
Step 5: Polishing Compound + Buffer or Strop
After Cratex, switch to a polishing compound. Apply compound to your felt wheel or strop, and work the blade in smooth, consistent passes. This is where satin becomes mirror.
Common Mistakes
Skipping grits. Every shortcut shows. You cannot jump from 220 sandpaper to Cratex Extra Fine and get a mirror.
Inconsistent direction. Cross-hatched scratches from changing direction show clearly under mirror polish.
Too much pressure. Pressing harder doesn't speed up polishing — it creates heat and can leave deeper marks.
Not cleaning between grits. One stray coarse particle means starting over.
How Long Does It Take?
A full mirror finish on a standard-size knife blade takes most makers 2-4 hours. The Cratex portion is typically 30-60 minutes. The investment is worth it — a mirror-finished blade commands higher prices and demonstrates a level of craft that buyers notice immediately.