The knife. This ancient tool – employed daily for over 2.5 million years – has whittled itself to an undeniable place of importance in our collective development as a species. But which of us can claim that their knowledge of this civilisation-carving essential goes further than being able to distinguish its blade from its handle?
Knowledge is power. And, as with all things, there is more to know than meets the eye. Getting acquainted with the various parts of a knife will ensure you know what to look for when choosing a blade to serve alongside you and your culinary endeavours.
What components make up a knife?
Firstly, let’s break down the anatomy of a blade. These parts, all with their own functions and variables, contribute to a knife’s performance and suitability for different kitchen tasks.
Here are the ten main components:
Point: this is the very top of the knife where the blade’s edge and spine meet, generally (with the exceptions of the Nakiri and the Cleaver) at an acute angle. The point is best used for scoring, piercing, and making precise, delicate cuts.
Tip: the first third of the blade. The tip is used for fine slicing tasks such as the initial cuts made when dicing an onion. On certain knives like the Chef’s Knife, the tip is curved slightly to allow a rocking motion when chopping. By contrast, Santoku tips are typically flatter, which better lends them to up-and-down cutting.
Cutting edge: the long, sharp edge where its two flat sides (known as flats or faces) meet. This is also the thinnest part of the blade.
Spine: the thickest part of the blade, opposite the cutting edge. The spine is dull; therefore pressure can be applied to it when needing extra force to cut through tougher materials like cartilage or thickly skinned squash.
Flat/face: the wide sides of the blade that connect the edge and spine. When comparing the anatomy of a Chef’s Knife to that of a Santoku, you’ll notice that the Santoku’s face is typically wider. This makes it more suited to tasks like scooping, or crushing garlic, seeds, and nuts.
Heel: the often obtuse angle found at the back of the blade’s edge, furthest away from the tip. The heel is used for cuts that require the most strength or pressure like going through bone or tough veg.
Bolster: the thickest part of metal that links the blade with the tang. It adds a balancing weight and acts as a finger rest. Japanese-style knives like ours (with the exception of our Devonshire Steak Knives) don’t typically have bolsters, as they can cause complications during sharpening. Instead, we use the heel and tip of the handle (or, collar) for a finger rest, and have designed a uniquely weighted tang for perfect equilibrium.
Tang: a knife’s tang is the metal that extends from the blade to inside the handle. Types of knife tang include 'partial-' or 'half tang', where the tang extends only down the handle, or 'full tang', which extends the whole length of the handle. Our new knives’ tangs feature a precisely positioned steel weight, giving our blades impeccable balance – and giving you effortless dexterity. We call this novel system Equipoise™, and it has already won a European Product Design Award.
Handle: no points for these final two. The handle, as the name suggests, is where the knife is held.
Butt: the bottom of the handle.
Blade geometry: single bevel vs. double bevel
To explain a knife’s bevel, we must first picture the cross section of the blade. Imagine you’re looking at the blade from the perspective of the handle, it should appear as an isosceles triangle. The bevel is the section of the triangle that has been sharpened to a point. If it has been sharpened on just one side, it’s a single bevel (or single edged knife), if on both sides, it’s a double bevel (or double edged knife). Single bevel blades are great for shaving and peeling, commonly appearing on scissors, chisels, and peelers. They are also the most classical knife to use for sushi. All our blades are double bevelled as they are the most versatile, and often more durable, edge.
Knife hardness
Rockwell Hardness is an industry standard test for measuring the strength of steel. To do this, a machine presses a conical diamond into the metal. After two passes, the depth of the indentation and amount of force used are measured and a figure is calculated (HRC or 'Hardness Rockwell C'), with a low number indicating softer steel and vice versa. Soft steel dulls faster but is easier to sharpen, whereas hard steel stays sharp for longer but is prone to chipping.
To ensure a blade is durable without being brittle, but also stays sharp for longer, a knife’s Rockwell Hardness should be around 55-60 HRC. We use Japanese steel, AUS-10, for all our blades – which has a hardness rating of 58-60 HRC – as it gives a consistent performance without the need for frequent sharpening.>