How To Sharpen a Knife

I was 45 years old, with nearly four decades of accumulated outdoor experience—fishing, hunting, guiding, sea kayaking, expedition travel, natural-history writing—when I finally confessed something to myself.

I was lousy at sharpening knives.

Oh, I could sharpen a knife so that it cut or skinned or carved just fine. But the edge always seemed to go away a lot quicker than I thought it should, and trying to touch it up in the field never seemed to work. I took to carrying two knives on deer and elk hunts just so I could be sure of getting through the entire animal. And these were not cheap knives.

Finally, I decided to educate myself. I did a bunch of research, then enlisted the expertise of a local bladesmith. And I did learn—to the point, in fact, that a few years ago I challenged myself to field-dress an entire cow elk using just my vintage Puma Trapper’s Companion, an exceedingly rare collector’s item with a flat-ground four-inch blade. And with just a few light swipes on a ceramic honing rod during the process, it worked. At the end of cleaning that elk, my knife would still shave hair off my arm.

How did I accomplish this leap in skill? I learned to master the burr.

There are dozens of products that can sharpen a knife effectively, from simple Arkansas stones to $1,000 systems of awesome complexity. But virtually all of them work by abrading material from first one side, then the other, of the double bevel that forms the knife’s edge. And each time you abrade material from one side of the bevel, it raises a tiny curl of steel—a burr—on the other side.

The simple essence of effective sharpening, and of creating a durable edge, is twofold:

• To produce an even burr along one side of the edge, then to alternate, using either increasingly fine stones or increasingly fine strokes, until that burr is reduced to a microscopic filament of steel that can be wiped away with a quick hone.
• To make sure the angle of the resulting edge is appropriate for the knife and its intended use.

That’s it.

What I had done wrong all my life was to sharpen my knives to the point at which the edge felt sharp and cut well, but still had a very fine burr left on it—a “wire” edge almost impossible to feel. The wire edge felt sharp and it cut superbly, for a while. But underneath it, I had not actually sharpened the edge of the blade to a perfect apex, and as soon as the wire wore away I was left with a less-than-sharp blade.

A Sharpener’s Stone

My Tucson bladesmith set me down with a simple set of Japanese waterstones (800, 1200, and 3000 grit) and a knife I owned. The first thing I learned is that, contrary to tradition, you don’t have to swipe the blade forward on the stone; drawing the blade backward for the sharpening stroke works just as well and it actually reduces the chance of the blade gouging the stone.

I learned to match the factory bevel by using a felt marker to blacken the edge, which with a couple of strokes would indicate if I was holding the spine of the knife too low or too high. I learned to make long, sweeping pull strokes the length of the blade while using as much of the stone as possible, with around five to six pounds of pressure on the blade (we used a postal scale to help me roughly judge the pressure I used), spreading the fingers of my off-hand along the blade to keep the pressure even. With just a few passes I could easily feel the burr on the opposite bevel by sliding my thumb from the spine toward the edge; as soon as the butt was apparent along the full length of the blade it was time to switch sides—no need to grind off more steel than necessary.

After four passes of six swipes each on each edge I switched to the 1200-grit stone and repeated the process. By then I could barely detect a burr and the knife felt as keen as any I’d ever sharpened. I used the same stone to take off that burr, this time by slicing forward lightly five times on each side, then four, three, two, until I was lightly slicing one time in each direction. I could actually see the finest filaments of the burr in the slurry of the stone. Finally, I finished with the 3000-grit stone, drawing the knife again but lightly so as not to raise a new burr, just polishing the edge to a mirror finish. My instructor handed me a page from a magazine to test the blade. The knife effortlessly sliced off half-inch wide strips of the paper. In ten minutes, I had made that knife sharper than it had ever been.

It's All in the Angle

The angle of the edge you want depends on the knife and its intended use. Some Japanese chef’s knives have extremely narrow bevels—11 or 12 degrees (that is, 11 or 12 degrees on each side of the blade). These knives excel at fine slicing, but even given their superior steel the edge can be damaged with rough use. Most American and German chef’s knives have a slightly more robust edge—15 to 17 degrees or so. On the other hand, a Scandi-grind bushcraft knife, designed to withstand occasional batoning through two-inch-thick tree limbs, might have a 28 or 30-degree bevel. Most hunting knives fall in between this at around 20 to 24 degrees.

Once you have sharpened the knife to the point where the burr is nearly microscopic, you can remove it on a stone, as I did above, or by stropping on a piece of leather, or even by simply drawing the edge along a block of wood or a thick piece of leather.

In use, a knife with a proper edge like this, and good-quality wear-resistant steel, will not readily dull; instead, the edge will gradually fold over almost invisibly. Once you notice this in your work, a quick few backward strokes on a ceramic rod, alternating each side, will generally restore the edge fully. Some knives made with superior modern steels can go through dozens of such procedures before actual sharpening is again necessary—and then you’ll only need to remove a tiny bit of material if you are using a controlled-angle sharpener that precisely replicates your previous work. 

Cared for in this fashion a knife should last a lifetime. That’s why I have no hesitation in using that Trapper’s Companion in the field—as its maker intended—rather than keeping it in a box to be taken out and admired now and then, its soul dead and buried.

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