How is the sharpness of a knife measured

Leo's knife blog

You have just freshly sharpened your knife, now the question arises as to how you can best determine whether the sharpening worked. There are a number of ways to determine how sharp a knife really is. In the picture above you can see a typical test method for razors, in which a hair is guided past the razor blade about a centimeter away from the fingers that are holding it. If it is sharp, it will cut the hair in the process.

Check out the following video to learn more test methods that are also suitable for kitchen knives and hunting knives.

Now the only question that remains is which severity test method is exactly the right one for your application. I personally come with that

  • Thumb test and subsequent shaving test to discover residual burrs, quite right with normal knives
  • I like to do the paper test when I've refurbished a knife and there might still be breakouts in the cutting edge. The cut then goes well until you get to the paper with the blunt point of the knife, then the knife hooks and the paper usually tears. So I know where I still have to regrind.
  • I only do the hanging hair test, in which a hair is cut off about one cm above the clamping point of the fingers, with razors.
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