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Testing Manual Knife Sharpeners

By Hannah Crowley Published

Can a compact, inexpensive tool keep your kitchen knives in top shape?

Update, September 2020

This story has been edited to focus only on manual knife sharpeners; see this story for updated information on our favorite electric knife sharpeners.

Japanese bladesmiths have long favored chef’s-style knives with blades that are ultraslim—that is, sharpened to about 15 degrees on either side of the blade—and for good reason: In addition to being thin and lightweight, these blades have a supernarrow cutting edge, which helps make them razor-sharp. We’ve also come to favor a thinner edge. After years of testing dozens of chef’s knives, our longtime favorite is from Victorinox, a Swiss-made knife that is sharpened to 15 degrees on either side of the edge, allowing it to push and slide through food more easily than do more traditional European blades sharpened to at least 20 degrees.

 Over the past decade the trend toward slimmer knives has continued to spread, as European manufacturers including Wüsthof, Henckels, Messermeister, and Mercer have launched their own 15-degree knives and sharpeners. (In fact, Wüsthof and Henckels discontinued their 20-degree knives.) 

To maintain that narrow edge, we use a tool specifically designed to sharpen a blade to 15 degrees. (We’ve also reviewed sharpeners designed for knives with 20-degree edge angles.) Our favorite electric models for 15-degree edges, both from Chef’sChoice, do a fine job of restoring an ultrakeen edge to a 15-degree angled chef’s knife. But what about manual models, whose smaller profiles and lower pricetags make them an appealing option? We rounded up five manual knife sharpeners designed to put a 15-degree angle on a knife, priced from about $20 to about $50, and headed for the kitchen.

To evaluate them, we bought five of our favorite Victorinox chef’s knives and assigned one to each sharpener. We then dulled the knives identically and sharpened them according to manufacturer instructions. To assess sharpness, we slashed sheets of copy paper and sliced delicate tomatoes, repeating the dulling, sharpening, and slicing process four more times with multiple testers (for more information, see Testing Knife Sharpness). We also compared the manual sharpeners’ performance with that of our favorite electric models. 

How Manual Sharpeners Work

All manual sharpeners work similarly: The user repeatedly drags the blade against an abrasive surface at a set angle, which trims and reshapes the blade by removing microscopic amounts of metal that are blunted or too far out of alignment. (Using a honing rod is for knives that are less dull, as it removes very little metal and primarily repositions metal on the blade edge that is slightly out of alignment). With electric sharpeners, the abrasives are on motorized wheels or belts that spin against the blade; with manual sharpeners, they’re either on nonmotorized wheels or the abrasive material itself is fashioned into a V-shaped slot through which the user pulls the knife.

Despite sharing similar mechanisms, the sharpeners we tested produced dramatically varied results. There were differences in user-friendliness: Some came with unintuitive directions and designs or fussy cleaning requirements. We docked points for these flaws.

But what really divided the pack was how sharp—or not—the knives were after we sharpened them. Some models barely restored the knife’s edge and others actually damaged it, rendering it uneven or jagged so that the knife struggled when it came in contact with the food. And then there were the best sharpeners, which put such a keen edge on the blade that it almost felt sharper than it did out of the box.

We first checked to see if electric and manual sharpeners performed comparably—and for routine sharpening, they did. (Repairing deep nicks was another story; more on that later.) It wasn’t until we examined the inner workings of the sharpeners that we realized that two key factors were determining how effectively they sharpened.

The Best Abrasives for Sharpening

First, the type of abrasive. The models we tested used three different kinds: carbides (a combination of metal and carbon), ceramic, and diamond. Our least favorite models featured carbides or ceramic, materials that proved problematic in part because they have what Mike Tarkanian at the Massachusetts Institute of Technology’s Department of Materials Science and Engineering calls a “high coefficient of friction.” This means that they are relatively sticky and grab at the surface of the blade more than diamond does. As a result, sharpeners made of these materials rough up the surface of the blade, making it move through food less efficiently. In addition, ceramic and carbides are also softer than diamonds and degrade more quickly, shortening the life span of the sharpener.

Diamond, on the other hand, is the hardest material in the world, which makes it strong and durable for sharpening. Its coefficient of friction is also relatively low, which allows it to glide smoothly over a knife blade as it sharpens and thus produce a smoother, sharper edge.

Design of the Sharpening Slot Affects Results

The second factor affecting sharpness was the design of the sharpening slot, which determines the angle of the knife edge against the sharpening material. For the abrasive to put a consistently smooth edge on the entire blade, the blade must move through the slot as steadily as possible; if there’s any wiggle room, the blade can shift position slightly from stroke to stroke and emerge unevenly sharpened. 

Some of our sharpeners had poor blade support, so testers struggled a bit to maintain a constant angle and naturally eased up on pressure when the blades were almost through the slot, lest they push the blades off the sharpeners and onto the counter. As a result, the knives assigned to these sharpeners had noticeably duller tips that couldn’t cut through paper and squashed tomatoes flat. Examining the blades under a high-powered microscope at MIT confirmed that they were utterly ragged from all that wobbling. The best design had high sides that held the blade at a precise, secure angle so that testers could draw it through the chamber with even pressure. 

Manual vs. Electric Sharpeners: What You Need to Know

Our favorite manual sharpener put razor-sharp edges on very dull knives and was easy to use. But whether you buy a manual or electric model depends on your needs and personal preferences. Manual sharpeners are smaller, lighter, cheaper—our top-rated manual sharpener costs about $50 while good electric sharpeners are typically more than $100—and easier to store. They also don’t need to be unpacked and plugged in for use, making them a more convenient option for routine upkeep.

But what even the best manual sharpener can’t do is repair extensive damage to a blade. When we filed two identical notches into the ends of each knife and then ran them through their respective sharpeners, the winning manual model hadn’t made much progress after 300 strokes. But since our favorite electric models put the abrasive in contact with the blade at a much higher speed, they quickly repaired the damage, giving the electric sharpeners a distinct advantage over manual models. Our top-rated electric model required only 76 strokes to make a severely damaged knife look and cut like a brand-new blade. 

The Best Manual Knife Sharpener for 15-Degree Blades: Chef'sChoice Pronto Manual Diamond Hone Asian Knife Sharpener

Our winning manual sharpener’s diamond abrasive, supportive sharpening slot, and intuitive design made it the standout favorite, putting a keen edge on our kitchen knives. It’s compact to store and easy to use, making it quick and convenient to keep your knives sharp and ready to cook.

Equipment Review Manual Knife Sharpeners

Can a compact, inexpensive tool keep your kitchen knives in top shape?

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16 days

Absolutely the best chicken ever, even the breast meat was moist! It's the only way I'll cook a whole chicken again. Simple, easy, quick, no mess - perfect every time. I've used both stainless steel and cast iron pans. great and easy technique for “roasted” chicken. I will say there were no pan juices, just fat in the skillet. Will add to the recipe rotation. Good for family and company dinners too. I've done this using a rimmed sheet pan instead of a skillet and put veggies and potatoes around the chicken for a one-pan meal. Broccoli gets nicely browned and yummy!

Absolutely the best chicken ever, even the breast meat was moist! It's the only way I'll cook a whole chicken again. Simple, easy, quick, no mess - perfect every time. I've used both stainless steel and cast iron pans. great and easy technique for “roasted” chicken. I will say there were no pan juices, just fat in the skillet. Will add to the recipe rotation. Good for family and company dinners too.

9 days

Amazed this recipe works out as well as it does. Would not have thought that the amount of time under the broiler would have produced a very juicy and favorable chicken with a very crispy crust. Used my 12" Lodge Cast Iron skillet (which can withstand 1000 degree temps to respond to those who wondered if it would work) and it turned out great. A "make again" as my family rates things. This is a great recipe, and I will definitely make it again. My butcher gladly butterflied the chicken for me, therefore I found it to be a fast and easy prep. I used my cast iron skillet- marvellous!

11 days

John, wasn't it just amazing chicken? So much better than your typical oven baked chicken and on par if not better than gas or even charcoal grilled. It gets that smokey charcoal tasted and overnight koshering definitely helps, something I do when time permits. First-time I've pierced a whole chicken minus the times I make jerk chicken on the grill. Yup, the cast iron was not an issue.