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You can get a knife made out of the same type of stuff as the mug you use for your morning cup of joe. And these knives are mega-sharp — so sharp they make those Ginsu knives from years back look like a rubber hose. However, ceramic is a fragile material — are these knives practical?
Kyocera Ceramic Knife
The leading maker of Japanese Ceramic knives, Kyocera, certainly makes a sharp knife. But just how sharp is it? And if it is ceramic, is it really practical at all? Or will it just shatter unless you do anything but carefully slice tuna for sashimi, like a Japanese Sushi chef?
The Key to Sharpness is Hardness
Good questions! Let’s start with how sharp a Kyocera or other ceramic knife might be. The key to how sharp the material can be is its hardness.
In terms of steel, you might hear knife makers telling you how hard their steel is, to make you want to buy their knives. The hardness of steel is described by the “Rockwell number.”
With kitchen knives, you’re probably getting a Rockwell number somewhere between 54 and 64. The higher the number the harder the steel, and so the more potential for sharpness.
Sharp Like a Surgeon’s Scalpel
Ceramic knives are made of material that is twice as hard as the hardest steel. This probably doesn’t mean that they can be sharpened to an edge that is twice as sharp, but, they are as sharp, if not sharper than any razor blade.
The blade of a ceramic knife compares with a surgeon’s scalpel, and it will glide through a piece of tuna just like a scalpel glides through flesh, producing a clean cut.
It is probably not true to say that ceramic knives are sharper than all steel knives, but they are sharper than any steel knife you are bound to own, or ever own.
A video demonstration is probably the best way to see the sharpness of a Kyocera ceramic knife. Yes, the knife looks like a toy to me, as well, but it is not something with which to play! Look how sharp this knife is:
Will Ceramic Knives Shatter Like Glass?
Back to the material. It’s not the same type of “ceramic” as in your coffee cup. And, no, although you may have heard that these ceramic knives will “shatter like glass” if you drop them or knock them against something hard, that is not true.
The material is brittle, and you could chip a piece of the blade away, and that would not be good, but it’s not like dropping your coffee cup. Heck, it’s not even like dropping your iPhone.
How are Kyocera Ceramic Knives Made?
Kyocera, the first company to produce these ceramic blades, and the largest manufacturer today, makes them out of a material called zirconium dioxide. This may sound familiar.
If it reminds you of fake “cubic zirconia” diamonds, you’ve got it. Cubic zirconia is a crystallized version of zirconium dioxide. It is an extremely hard material and the blades are about 50 percent harder than steel.
The zirconium dioxide the company uses is mined from Australia. They grind it into a powder, and then mix it with water and crush it into a pasty sludge, which is then dried to leave behind an extremely fine powder.
The powder is put into molds, and the molds are subjected to three hundred tons of pressure, which binds the powder into a solid knife-shaped blank.
The blanks are put into a very hot furnace and baked to harden them. After they are out of the oven, a handle is attached and the blades are ground, honed, polished, and buffed to a shiny white (or black) knife that resembles a plastic toy, but is anything but.
Light as a Feather (not really but super-light), and Super-Sharp
As you can see in the video, the ceramic knife is super-light. Compared to your heavy steel chef’s knife, it will feel like a feather in your hand.
The lightness of the knife should tell you something about its supposed potential to shatter. It is not as heavy as a glass or a ceramic cup. It is a fraction of the weight, and therefore the impact it makes when you drop it imparts less force and therefore has less potential for damage in the first place, even if it were so fragile, which it is not.
Some cooks may have a hard time adapting to this lightweight feel, and they may not like it. However, in the demonstration, the knife glides through yellow bell peppers just by the slight weight of the knife alone.
It is sharp, sharp, SHARP!
What’s more, it is smooth. Food doesn’t stick to the sides of the blade like your average steel knife.
This lack of friction is something that aids in slicing, in particular for slicing super-thin slices of soft meats — or tuna, of course.
Good for “Normal” Use, But What is Normal?
I’ve read that ceramic knives are good for “normal home use.” Well, normal for me may not be normal for you. You can’t attack a watermelon with a ceramic blade, for instance.
For everyday work, like chopping vegetables, fruits, and boneless meat, they are a whiz. But remember, they have virtually no flexibility and are hard and brittle.
Knock a ceramic blade against a chicken bone and you’ll probably end up with a chipped edge. Smashing a clove of garlic will have a similar result.
I think you get the picture. I use my awesome steel chef’s knife like a hammer (yeah, I know, I know). You have to be respectful of a ceramic knife: its awesome sharpness and its fragility.
Still, ceramic knives aren’t so fragile they are impractical. They will keep their edge for years if used with care, but once they lose it, you can’t just hone it with a few swipes of the steel, or take it to your local knife sharpener.
You have to send it back to the manufacturer, the only people able to sharpen these things (or so it is claimed).
Kyocera now offers an electric ceramic knife sharpener. They will, of course, sharpen your Kyocera ceramic knife for you, and they still offer a lifetime service, should you ever need it.
I know what you’re thinking: I have to ship my knife to Japan?
No — Kyocera is a big company. They have facilities in the States.
The video below provides a demonstration of a Kyocera electric ceramic knife sharpener in use.
I also came across a video of how Kyocera sharpens its ceramic knives at its Orange Country, California facility. The video has been removed since this article had been published. However, they use grinding wheels.
There is nothing mystifying going on here.
If you’re like me, you might be thinking “I thought these things were supposed to never need sharpening?”
So, why all the talk about sharpening? Well, look at the stack of boxes in the video. They all have ceramic knives in them, shipped to Kyocera by customers. So…there.
They will stay sharp for years, with careful use, but regardless, I don’t think most knife companies provide lifetime sharpening as Kyocera does.
Given the juxtaposition of a professional carefully sharpening the blade of a ceramic knife in the second video, and the electric sharpener in use in the first, which looks much like any electric knife sharpener, except perhaps for the actual grinding wheels, I’m a bit skeptical.
We know that electric knife sharpeners don’t work. At least, I know they don’t. I had one sitting around for years after I discovered that it did NOT properly sharpen my good knives. It was a doorstop, at best.
However, I don’t see why the company would produce a sharpener that did not work or potentially damaged the knives, while still offering lifetime service or replacement.
Surely, Ceramic Knives Cost Hundreds of Dollars
Nope. If you like the idea of a razor-sharp ceramic knife that you can cut your finger with but get no scar because the cut is CLEAN (just kidding), it is quite practical to own, even if it can’t be your only knife.
You can get a Kyocera 3-piece ceramic knife set for 80 bucks. It comes with a 6-inch Chef’s knife, a 5-inch micro serrated knife which I would call a utility knife, and a 3-inch pairing knife — all for the price of one high-quality steel chef’s knife, and not even a top-shelf one.
- Culinary Companion: Explore the world of Kyocera ceramic knives with our Ceramic Revolution Series Professional Chef Knife, tailored for cooks seeking exceptional value and performance in the kitchen.
- Hand-sharpened Proprietary Blades: Made from Kyoceras zirconia material, our Japanese knife blades offer superior quality and performance. With exceptional durability, they outlast traditional blades by up to 10 times. A must-have for your kitchen.
- Lightweight Chef Knife: Enjoy the convenience of lightweight knives that offer effortless handling and cleaning. The non-reactive ceramic material prevents oxidation, preserving the freshness of your ingredients for flavorful, healthy cooking.
- Versatile and Reliable: From slicing fruits and vegetables to handling boneless meats, these knives excel in various kitchen tasks. Please note that they are not suitable for hard or frozen foods, ensuring optimal performance and longevity.
- Complete Set: Unleash your cooking potential with the 7” or 8” Professional Ceramic Chef Knife. Replace your kitchen gadgets with these knives and embark on a culinary journey with confidence.
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A 6-inch chef’s knife may be a little small for many cooks, even if you don’t need the added weight of a large knife. They offer a Kyocera 7-inch ceramic professional chef’s knife that comes in their special black series which is supposedly more durable. It goes for a bit over 45 bucks.
Also, if you know anything about Benriner Japanese mandoline slicers, you might be thinking, why don’t they make a mandoline with a ceramic blade? Well, they do: Kyocera produces one.
