What Makes A Good Knife?

Let's define what we think a "good" knife is before anything else. To us, there's three main categories to focus on, each with sub-categories inside it. At a base level though, we judge knives based on:

1. Kireaji (Flavor of Cutting) / "Sharpness"
2. Balance
3. Maintenance Characteristics

We'll delve into each of these categories in detail throughout this article, and you can weigh them based on what categories are important to you.

A key thing to remember is this is what we think a good knife is - what is good for you might be different! Use this as a general guide, and build your research from here.

While kireaji can translate as "sharpness," in this case with Japanese context it can be referred to it more as the "taste" or "flavor" of sharpness. Or in a way, the "feeling" behind the cutting of something.

Realistically though, it doesn't have an equivalent word in English.

Kireaji is very much a term of it's own, and in Japan, this is a unique cultural expression that captures the concept of "how it cuts". For instance, while the English word "sharpness" is translated as surudosa in Japanese, the nuance of kireaji is slightly different. If directly translated it comes out as "flavor of cutting", which is quite confusing. Similarly, in many other languages, there isn't a perfect equivalent for kireaji.

In Japan, there's a diverse range of sensations associated with kireaji. For example, there's the concept of amagire or "sweet cut," which describes the feeling of a knife cutting smoothly even without being extremely sharp (we go into this concept more in our blog about Blue Steel #2). This also implies that the cutting technique itself contributes to the taste. For example, when slicing fish, even just the method of cutting alone is enough to create or identify a dish. This promotes the notion that how something is cut is crucial to how it tastes.

Perhaps this is one of the unique Japanese cooking perspectives that has elevated Japanese knives to be recognized and valued worldwide.

Our company's concept of kireaji

With our store and team, we believe kireaji can be broken down in three seperate components:

1. Edge Retention, which refers to how well sharpness can be kept with proper usage.
2. Piercing Ability, which refers to how well a knife pierces into an ingredient.
3. Cutting Ability, which refers to how smoothly a knife cuts after it's entered an ingredient.

Edge retention differentiates expensive and inexpensive knives. By not compromising on materials or creative processes, we're able to produce knives that cut for a long time and as a result have excellent edge retention.

Piercing ability is mostly dependent on the characteristics of the steel material used. However, any edge with proper toughness and sharpness down to the micron level will give an amazing piercing experience. A well-forged knife with the same steel composition evenly throughout will have a firm edge too, even when magnified to a microscopic point.

A good cutting ability mostly comes down to how the knife blade itself is processed, such as with honing and sharpening techniques. The edge of the blade is thin while the other part of the blade gets thicker when approaching the spine. Keeping the blade thin and creating a properly rounded curve as a "clam-shell blade" or hamaguri-ba, can give a great contiunous cutting ability and can cut without food sticking to the blade. Conversely, if the blade is just thin but not in a proper form, it won't have enough strength, making it difficult to resist the pressure against the ingredient it's cutting. This in turn makes it more difficult for the knife to properly and continously cut through. You might discover this trait this more easily while cutting harder root vegetables like sweet potatoes.

In short, for us, a knife with good kireaji holds its sharpness well, penetrates into ingredients easily and has a sharp general cutting ability, without catching on the ingredients.

The second key factor is the balance of a knife - that is, how it feels when it is held and more importantly when it is used. Sadly, there's no real "correct" answer to this as everyone's hands are different in terms of size and grip strength amongst other things. Even if we claim a knife "has excellent balance," it simply may not for you because your hand is different to the hands from people in our store - we simply don't know how well the knife balance might apply to another user. Of course, this can go the opposite way too - a knife that works for you balance wise may simply not work for us.

The best way to solve this issue is to go to a knife store and hold the knives to compare, and we recommend this everytime customers come into our shop in Osaka. But of course, this isn't always possible - there's a good chance if you're reading this you're on a global website and not in Japan for example. So to try to solve that in our own way, we split how we measure balance into three seperate sub-categories.

1. Ease of grip
2. Resistance to fatigue
3. Ease of power transmission

Ease of grip is simple to explain - this is how well the handle fits into your hand. If it's easy to grip, there's no need for excessive force. While there's many stylish handles out there these days, for those using a knife for a long time in a day, how easy it is to grip is really important. This handle needs to be able to grip while cutting, peeling, doing push cuts and all kinds of other movements.

Resistance to fatigue is how well you can hold the knife without getting tired. We often see Japanese handled-knives perform well here due to their lighter weight, but sometimes people prefer to use heavier knives for a long time and let gravity do some of the work.

Ease of power transmission is how well a suitable center of gravity is created in the knife. A knife with a good weight balance between the blade and handle will transmit power easier, and be less tiring to use. If the tip of the blade is heavy, it becomes more difficult to be precise with it, but that weight can also be used to an advantage by letting gravity assist you. Additionally, if the handle side is heavy (like in Western-handled knives) it can be difficult to do delicate work because the cutting edge is controlled by the arm more than the wrist. Ceramic knives are a great example of this, as while they're very innovative thanks to their extremely light and sharp blade for their price, their center of gravity is all the way over on the handle side, so it takes getting used to.

Gyuto and santoku knives should have their center of gravity where the index finger rests, whereas Japanese-handled knives should have it around the base of the blade. The material of the handle itself and whether or not it has a bolster changes the center of gravity heavily, so keep this in mind when you're considering purchasing off the internet and not being able to hold it first.

Where possible, try to hold the knife - see if it fits right in your hand and feels good to use.

Maintenance Characteristics can also be referred to as how well sharpness on a knife can be reproduced. This is crucial if you're aiming to have a knife that will last for a lifetime, especially if you're investing into a good quality knife. We feel maintenance characteristics include the following three sub-categories:

1. Rust resistance
2. Ease of sharpening
3. Chip resistance

Rust resistance very much is what it says - how resistant a knife is to the natural chemical reaction of rusting. If we compare knives that have the same sharpness level, then carbon steel knives can be made at a cheaper cost than stainless steels, but they require regular care to prevent rusting. This is especially important after using and washing them, like making sure they are fully dry and removing all moisture. Rust is the number one enemy of knives, as it can cause significant steel deterioration leading to pitting in the knife or even transferring the rust onto food. Stainless steel knives in comparison, are significantly more resistant to rust compared to carbon steel, offering much more peace of mind in terms of general knife maintenance and as a result they generally perform well in this subcategory.

Ease of sharpening is also important. As you use any knife, the edge will gradually become rounder each time it hits the food and cutting board. When the edge becomes rounded, it loses cutting ability. That means a blade will need to be regularly resharpened as it's used. The ease of sharpening mainly depends on the steel material and the making process. High quality steels are thankfully resistant to wear and rounding, resulting in longer-lasting sharpness. However, this generally also comes with the caveat of being difficult to sharpen, creating a trade-off between ease of sharpening and good edge retention. That said, thanks to the effort of craftspeople, steel manufacturers and whetstone makers, there are knives that manage to excel in both areas. Alternatively, the knives may feature a wear-resistant, yet easy to sharpen steel - generally this is due to its thickness. When choosing a knife to be a long-term item, we tend to recommend prioritising how easy it to sharpen over its edge retention. There's no such thing as a knife that doesn't need resharpening so this is always a factor you need to consider.

Chip resistance refers to both chipping resistance and impact resistance, such as when the knife hits something hard or is dropped. A knife is made chip-resistant by being well forged, resulting in a good carbon composition evenly distributed throughout the blade steel, or by using a durable steel in itself, and by sharpening the blade properly during it's bladesmithing process. Chips are a big enemy of knives, as they require significant sharpening to fix, heavily impacting the total lifetime of a knife. It's important to factor this in, even if you think you'll never drop the knife.