Testing Chef's Knives

While it’s hard to imagine a factory-made knife that could surpass this one—either in price or quality—every so often we revisit the category to be sure. This time we sought out 8-inch chef’s knives (the most all-purpose size) and capped our budget at $50. Ten models met our criteria—including a “consumer” version of our previous winner, a model that will eventually be available only commercially. We enlisted six testers, male and female and with varying hand sizes and kitchen abilities, and got each of them to spend weeks hacking, dicing, and chopping their way through 10 whole chickens, 10 butternut squashes, 10 onions, and 10 bunches of parsley. What we’re always looking for: a strong yet agile blade that feels comfortable and secure in our hands.

By the time we wrapped up testing, we’d found one standout favorite and a couple of other knives that passed muster, but the rest of the models lagged behind, many of them by a considerable margin. While the top performers capably broke down whole birds and slid through dense squash, the bulk of the lot struggled—and at the end of testing, we had piles of ragged onion pieces and bruised parsley leaves to prove it.

The obvious question: What was it about our lone winner that made it a stellar performer? Its design wasn’t radically different from that of other knives, and it was one of the least expensive knives in an already low-cost lineup. We decided to get to the bottom of what made this one knife so much better than all the others.

The top priority for a good knife is razor sharpness. Right out of the box, some knives were sharper than others. Still others started out fairly sharp and quickly lost their edge. Either way, a dull knife turns a small pile of potatoes into a mountain and makes for sloppy food. (“I can hear the cells bursting,” said one tester as a dull blade sprayed onion juice across the cutting board. “Chicken, I feel sorry for you,” said a second frustrated tester, vainly hacking away with another comparatively blunt edge.)

Sharpness is partly determined by the thinness of the blade’s cutting edge. Any material can be sharp if its edge is thin enough—this is why an otherwise harmless piece of paper can deliver a paper cut. Traditionally, Western knives have been sharpened to 20 to 22 degrees on each side of the blade while Asian knives are thinner—just 15 degrees on each side. However, those style markers appear to be blurring in favor of Asian knives: All the knives we tested are considered Western-style, yet when we asked the manufacturers, it turned out that half of the models sported 15-degree (or narrower) blades, including our top three favorites.

But a razor-thin cutting edge isn’t everything: If the metal is too soft, it will easily develop microscopic chips, dings, and dents, and the edge will wear down quickly. So what makes one type of blade harder than another? It begins with the composition of the steel.

Steel is an alloy that always includes iron and carbon, but it may also contain other elements chosen to add particular characteristics to the metal. We were able to find out that the products in our lineup used one of three basic steel alloys: x50CrMoV15, x55CrMoV15, and 420. (To make the first two alloys easier to reference in this story, we’ll refer to them simply as “x50” and “x55” steel, respectively.) When we checked the steel type of each blade against our ratings, we saw that knives made from the 420 steel were clearly inferior to blades made from the other two alloys, as they landed at the bottom of our rankings. These included the “dull,” “flimsy” model, which produced crushed, not diced, onions. Another blade made from 420 was the last-place finisher, which struggled to cleanly slice through sheets of copier paper (our standard sharpness test) and dulled rapidly as testing progressed. Meanwhile, the blades that started out sharp and stayed that way were crafted from x50 and x55 steel—and our top three models all used the x50 alloy.

These results suggested that the 420 alloy produced blades that weren’t as hard as those made from the other two metals. When we consulted Bob Kramer, a master bladesmith, and Merrilea Mayo, a materials scientist and former president of the Materials Research Society, both experts confirmed our hunch: 420 steel is indeed a softer metal than the other two alloys. This is because it usually contains less carbon and no vanadium, elements that act as hardening agents. So why would a manufacturer select for this quality? A softer steel is easier to cut into blades, lowering production costs. As for differences between x50 and x55 steel, their steel makeups are very similar, so we could only assume that something else was giving the x50 a literal edge over the others.

That something turned out to be how the metal is heated and cooled. Just as baking time and temperature affect the crumb of a cake, the “cooking” process determines the grain of a metal. For a harder product, small, close-knit grains are the goal. “Large grains,” Mayo explained, “are functionally useless for knife blades because they are so soft.” All manufacturers start the knife-making process the same way: by slowly cooling the molten metal. Next comes the proprietary part: a multistep tempering process of reheating and cooling the metal to help shrink the grains and/or encourage new, smaller ones to form. According to Mayo, tempering can have infinite variations, which in turn can lead to differences in grain size and pattern. We’re betting that the specific way it was tempered helped give our front-runner superior hardness. (Heat treatment might also explain why some blades made from the same x50 steel didn’t perform as well.)

As for the other half of the knife—the handle—we figured that preferences would be a dividing point among testers. After all, the comfort of a grip is largely subjective and depends on variables from the size of your hand, to how you hold the blade, to your knife skills, to whether you prefer a brawnier or more svelte handle or one that’s crafted from metal rather than nylon or wood.

Surprisingly, though, all six testers unanimously preferred one handle: that of our winner. This handle boasted no ergonomic grooves or bumps; compared with other models that we tested, it actually lacked design features. How could one grip—particularly one so basic-looking that it almost seemed underdesigned—feel like a “natural extension” of so many different hands?

We showed the knives to Jack Dennerlein, professor of ergonomics and safety at Northeastern and Harvard Universities, who offered a one-word explanation: “affordance.” This term, he explained, is what ergonomists use to describe the versatility that we ask of our chef’s knives. Cutting is a complex task, and a well-designed handle affords multiple grips for the range of angles and forces required, allowing us to confidently drive the knife downward through a chicken bone just as easily as we make precise cuts in an onion. Dennerlein said that when knife makers add grooves and curves to a handle, like those on some of the less comfortable handles in our lineup, they are telling us how to hold the knife instead of allowing us to choose what’s most comfortable. Sharp square angles on many of the knife handles and blade spines were a prime example of this. They limited where our hands felt comfortable, as did pronounced bolsters, both of which dug into our palms when we used the so-called pinch grip, for which you choke up on the knife and grasp the back of the blade between your thumb and forefinger for control. Other handles were either too thin—“like holding a tube of lipstick with a sharp blade at the end”—or too wide.

We also knocked points off one knife's score for a “bellylike” curve to its grip and an indented ridge along the top. The maker claims that these features are tailored specifically for the home cook, but we’re not sure why any cook would like them; we found that they made our fingers splay out as we grasped for a better hold, causing fatigue and decreasing control. Furthermore, the handle is made from a hard, slick plastic that didn’t offer a lot of friction between our hands and the handle. As a result, it felt slippery, especially during messy tasks like butchering a chicken.

But even when a handle was specifically designed to provide friction, it sometimes had other flaws. The plastic grip made of open ridges on one knife, for example, stayed put in our hands, but the deep grooves also dug into our palms. To some testers the wooden grips on other knives felt much better in hand, as the natural grain offered some traction, but to other testers these grips felt “rough.”

After nearly two months of testing, we tallied our results—and we can’t say that we were shocked to learn the winner. Once again, our previous favorite, the Victorinox Swiss Army Fibrox Pro 8" Chef's Knife, effortlessly ascended to the top spot for its exceptional cutting ability and a grip that all testers found particularly comfortable. Don’t be misled by its unprepossessing design: This model embodies a number of subtle features that have helped propel it to the top of our rankings for the past two decades. For one, there’s its plain-Jane handle. Made from a bumpy, grippy nylon material called polyamide, it has enough traction to stay put in your hand, and its basic design boasts the so-called affordance that makes it well suited for any kind of grip. Second, its blade is made of hard x50 steel—an alloy that Kramer agreed is likely put through a very fine-tuned heating and cooling process to develop the optimal hardness.

Third, the blade is sharpened to a thin 15 degrees. Given how easily the knife cuts through food, that discovery made sense, but it also raised another question: What’s the best way to maintain that narrow edge? The maker originally designed the knife for chefs and food industry professionals with the assumption that such users would be maintaining the edge on a sharpening stone. However, now that Asian-style sharpeners have become more widely available to consumers in Western countries, the manufacturer also recommends these for keeping the winning model's edge at a factory-sharp 15 degrees. Going forward, we’ll sharpen this knife on our winning knife sharpener.

Also worth keeping in mind is our winning manufacturer's plan to move our winning model out of retail stores in 3 years and make it available only to commercial outlets and restaurant supply shops, and only the consumer version will be available for retail sale. We hope that the company reevaluates that decision. Though the consumer version shares the winning model's outstanding blade, we’re not as enthusiastic about the former due to its less than perfect handle—and its $10-higher price tag. We will continue to monitor and report on the winner's availability.