If you've heard the term "hair-popping sharp," you may be wondering if we're about to suggest that you see if your knife will shave hair off your forearm. Many people check their edges that way, but let's face it, sooner or later you'll run out of hair on your forearms, so we'll give you some other options.
The first thing you'll want to do is make sure you've sharpened the entire edge, from one end to the other. Lay the blade flat against the plastic barrel of a Sharpie (or similar plastic object), raise the spine of the knife until the edge "grabs" the soft plastic, and then draw the blade across. If it slips, you've found a dull spot that needs attention.
Once that's done, check final sharpness by cutting paper. Around here we use ordinary printer paper or newsprint, paying attention to a couple of things. As you draw the knife perpendicular to the edge of the paper, it should slice easily and smoothly -- no snagging, no tearing. If it's not a smooth cut, then the knife's edge is "toothy" (think of a saw blade) and needs more work.
If you're looking for still another way to determine if your edge has achieved the desired sharpness, you may want to try knifemaker Murray Carter's "three-finger test." It truly works -- but rather than attempting to explain it here, we'll refer you to Murray's video tutorial.
To learn more, visit our Knife Sharpening page.