How to test your knife for sharpness

The best way to test a knife for sharpness is to use it. Almost nobody tells us how sharp we got their knives until after they have used them. Sure, we'll test them sometimes together. But they really know after they've cut a few things.

Slicing tomatoes is harder than slicing paper. But paper has is more available and less messy. A reasonably sharp knife will cut cleanly through paper. A slightly sharper knife will cut thin paper almost effortlessly.

A similarly sharp knife will feel like it's grabbing at your fingernail if you draw the edge across it with almost no pressure.

Of course there's the shave-the-arm-hair test. It takes a really sharp knife. If you wet the hair that doesn't count. Besides, it's really not practical for a professional.

If you can cut a hair all by itself it's SHARP! It's hard to get a picture of a hair, so this one doesn't exactly represent. To do the test fairly the hair should be cut about a half an inch from where it is held.

Remember the burr. Its significance can't be overstated. That's why barbers still use the old school leather strop for final razor sharpening. The edge of a really sharp instrument is ridiculously delicate.

Another great test is to look at the edge. Shine a light on it from behind. Anywhere there is a reflection there is a flaw in the edge. Get out the steel and be gentle.

In the picture the gentleman is checking for a burr by running his thumb across the edge from behind it on the blade. Don't cut yourself.