It is crucial to keep knives sharp so that they cut through food with less slippage. Dull knives are dangerous because a dull blade requires more force to do the job and so has a higher chance of slipping and missing the mark. Plus, poorly cut food will not cook properly. A sharp knife will produce food that is evenly cut and therefore will cook at an even rate. We'll show you how to sharpen kitchen knives—it's one of the easiest ways to instantly improve your cooking.
What You'll Learn
- How to Tell If Your Knife is Sharp Enough
- When to Use a Knife Sharpening Steel
- How to Use a Knife Sharpening Steel
- When to Use a Knife Sharpener
- All About Electric Knife Sharpeners
- All About Manual Knife Sharpeners
- All About Whetstones
- How to Use a Whetstone
- How to Sharpen Serrated Knives
- How to Sharpen a Santoku Knife
- Is it Possible to Over-Sharpen Your Knives?
- Degrees of Sharpness
- Knife Sharpening Kitchen Hack
- How to Store Your Knives to Keep Them Sharp
- Knife Sharpening Takeaways
How to Tell If Your Knife is Sharp Enough
A Scientific Glimpse: What a Sharp and Dull Knife Look Like Up CloseIn our knife sharpener research, we examined blades—from sharp (smooth and sharp) to dull (all chewed up)—under a high-powered laboratory microscope at the Massachusetts Institute of Technology’s Department of Materials Science and Engineering.
When to Use a Knife Sharpening Steel
A so-called sharpening steel, the metal rod sold with most knife sets, doesn’t really sharpen a knife, but rather it hones the edge of a slightly dulled blade. Sweeping the blade along the steel realigns the edge. Throughout this motion, make sure to maintain a 15-degree angle between the blade and the steel.
How to Use a Knife Sharpening Steel
When to Use a Knife Sharpener
If your knife is quite dull, you’ll need to reshape its edge. This requires removing a fair amount of metal—more than you could ever remove with a steel. To restore a very dull knife, you have three choices: You can send it out; you can use a whetstone (tricky for anyone but a professional); or—the most convenient option—you can use an electric or manual sharpener.
All About Electric Knife Sharpeners
How to Use: These machines are very easy to use. With electric sharpeners, the abrasives are on motorized wheels that spin against the blade. Always follow the manufacturer's instructions. In general: Turn on the sharpener, hold your knife securely but lightly (no need to press down hard; the machine does the work for you), and pull the blade through the desired slots slowly and smoothly. Alternate sides for sharpening both sides of your blade. Our favorite electric model features a dedicated slot for heavy damage, and it required only 76 strokes to make a severely damaged knife look and cut like a brand-new blade. This slot can narrow the angle of a traditional Western blade, converting it from 20 degrees to 15. We tested that claim by running a brand-new 20-degree chef’s knife through it for 20 strokes on either side of the blade (per manufacturer’s directions)—and it was significantly sharper than a second new copy of that knife.
All About Manual Knife Sharpeners
How to Use: With manual sharpeners, the abrasives are either on nonmotorized wheels or the abrasive material itself is fashioned into a V-shaped chamber through which the user pulls the knife. In general, pull the blade through the chamber with even pressure. Always follow the manufacturer's instructions.
All About Whetstones
How to Use a Whetstone
How to Sharpen Serrated Knives
How to Sharpen a Santoku Knife
Since our three favorite santoku knives have a variety of blade angles on their cutting edges, we wondered whether our winning knife sharpener, the electric Chef'sChoice Trizor XV, could sharpen them all. Happily, we discovered that it can when we uniformly dulled and resharpened their edges, they were as good as new.
Note that for knives with an asymmetrical edge, such as our winning santoku from Misono (read our full review of santoku knives), the sharpener manual directs you to use only one side of the machine's paired slots at each stage or honing, confining the sharpening action to that single side of the knife. In the final polishing slot, pass the other side of the knife through once, just to finish it off smoothly.
Is it Possible to Over-Sharpen Your Knives?
In short, the answer is no. Don't believe these common sharpening myths:
MYTH: Electric sharpeners take off too much metal.
TRUTH: With the right brand of electric sharpener, there’s no need to worry about excessive metal loss. Electric sharpeners do take off a small amount of metal each time you grind your knife—especially if you are using a coarse-grind setting to sharpen an especially dull knife. But our favorite electric sharpeners have three options for sharpening: coarse, fine, and a nonmotorized steel. The fine slot is the one you will use most often just to polish up a barely dull knife. Because you will be maintaining the sharpness of your knife with the lightest of the sharpening options rather than giving it an intense regrinding with the coarse slot, you shouldn’t worry about metal loss.
MYTH: For that matter, honing steels can take off too much metal.
TRUTH: Again, with the right tool, metal loss is nothing to worry about. The three types of steels on the market—regular, fine, and polished cut—all accomplish the same task to a lesser or greater degree. The rough, filed lines of the regular-cut steel are best for home cooks who only occasionally steel the edge of a knife. For professional chefs and meat cutters who use their knives for hours on end (and steel them multiple times per day), the fine and polished cuts are a better choice, as constant contact with the rougher surface of a regular-cut steel could wear away their knives’ edges.
Degrees of Sharpness
Knife Sharpening Kitchen Hack: Use a Coffee Mug
Need to sharpen a small knife, but don’t own a knife sharpener? If you find yourself with a dull knife but without a knife sharpener, you can use the unglazed bottom of a ceramic mug to sharpen small knives. Applying moderate pressure, hold the knife at a 15-degree angle and carefully draw the entire length of the blade across the rough surface.
How to Store Your Knives to Keep Them Sharp
Storing knives safely and securely can keep their blades sharper longer, and out of harm’s reach. We don’t recommend storing knives in a drawer; as knives are moved about they can nick each other—not to mention you, too.
Knife Sharpening Takeaways
- Sharpen your knives regularly. Even the best knives will dull over time with regular use.
- A sharp knife is a safe knife. It is crucial to keep knives sharp so that they cut through food with less slippage.
- Using a sharp knife will make your food taste better. Get the thin slices or a fine dice you're looking for, not large or ragged hunks. Precisely cut food will cook at an even rate and produce a much more successful dish.