The Why and How of Sharpness
If your knife doesn’t feel sharp after using your Wicked Edge precision sharpener, it might not be the edge—it might be the edge for the wrong job. Sharpness depends on the task you're preparing your knife for. This guide breaks down what sharpness really means, how to achieve it, and how to test for it effectively using your Wicked Edge sharpener.
What Is Sharpness?
Sharpness isn’t a universal trait—it’s a performance measure specific to the cutting task. A straight razor and an axe are both sharp in their own ways, but you wouldn’t want to swap their jobs. Your edge should be tailored to what you’re cutting. For example:
- A low-angle, highly polished edge slices cleanly through paper and shaves hair.
- A coarse, toothy edge bites aggressively into rope, cardboard, or tomato skin.
Match your angle setting and edge finish to the task. For help selecting the right finish, check out our guide on abrasive progression here.
Are You Sharpening All the Way to the Apex?
One of the most common reasons a knife doesn’t feel sharp is because the bevels aren’t meeting cleanly at the apex—the very edge of the blade. To confirm you’re reaching the apex, you must draw a burr.
What Is a Burr?
A burr is a tiny, raised fold of metal that forms when you've removed enough material on one side of the blade. It proves that you're sharpening the edge, not just polishing the bevel. You should be able to feel a burr form along the entire edge before switching sides.
Make sure you're using the Marker Method to identify your sweet spot and maintain the correct angle. Learn more about these techniques here: How to Find Your Angle and Drawing a Burr.
Are Your Diamond Stones Fully Broken In?
Brand new Wicked Edge diamond stones are aggressive—they can leave deep, inconsistent scratches on the edge that reduce refinement. As you sharpen more blades, the diamonds wear in slightly and produce a smoother, more uniform finish.
Visual Comparison of Scratch Patterns
Scratch pattern from a fully broken-in 600 grit Diamond Stone:
Scratch pattern from a not broken-in 600 grit Diamond Stone:
Want to know how long it takes and why it matters? Read more in The How, Why, and When of Diamond Stones.
How to Test for Sharpness
Once your edge is formed and refined, it’s time to test it. These methods work for nearly any sharpening style and finish.
1. Fingernail or Marker Bite Test
- Rest your fingernail or a Sharpie marker on the edge at a 45° angle.
- Gently pull downward—if the edge “bites” and resists slipping, it’s sharp.
- Do this along the entire edge to check for dull or flat spots.
2. Paper Cutting Test
- Use printer paper, notebook paper, or even newspaper for added difficulty.
- Push-cut through the paper or try slicing curves—both test edge refinement.
- Best results come from edges at ≤20° per side and ≥1000 grit finish.
3. Shaving Arm Hair
Use with caution. A well-refined, low-angle edge will cleanly shave arm hair, but accidents are common—especially at trade shows!
4. Hanging Hair Test
This classic razor test checks whether the edge “pops” a hair held lightly in contact. It’s a sign of exceptional refinement. See it in action here.
Final Thoughts
Creating a truly sharp knife means aligning your sharpening method with your cutting goal. Confirm you’ve reached the apex, break in your stones, and test with purpose. With the Wicked Edge system, you have the control to get the exact edge you need—whether it’s polished to a mirror or left aggressively toothy.
Learn more about Wicked Edge precision sharpeners here.
