The kitchen knife edge. The cutting surface. Where the rubber meets the road…ummmm…I mean where the knife meets the food. The more you learn about knives, the more choices you realize you have - for almost every part of the knife. Different tangs, different bolsters, different handles, etc. And the cutting surface is no different. So I thought it would be helpful to focus a little on the different elements of the knife blade's edge, some differences, and the specific purpose each one has.
Yes, yes, I know this isn't school, but sometimes it's helpful to start with a few definitions. So here are a few basic ones, class:
- Cutting edge: The sharp edge of the knife blade.
- Spine: The top of back edge of the blade (away from the cutting surface/edge).
- Edge angle: The angle at which one side of the blade meets the other. This is the angle from the center of the blade and measure from there to the outer side of the primary bevel.
- Inclusive angle: Both edge angles added together. For knife blades that are ground symmetrically, it’s simply twice the edge angle.
- Bevel: Any surface on the blade that has been ground to form the edge. The primary bevel is the one nearest the blade’s spine and the secondary bevel is the one closer to the knife's edge where the angle becomes more steep.
- Grind: The shape of the cross-section of the blade or how the blade is thinned to reveal the cutting edge.
This aspect of the knife blade is often overlooked; but is pretty important. A grind refers to the shape of the cross-section of the blade or how the blade is thinned to reveal the cutting edge. It refers to the angles used to taper the knife into a sharp edge.
In general, there are six primary types of knife grinds; only three of which are more commonly used in kitchen knives. The main six are:
- Hollow grind
- Flat grind* (also known as a “V’ grind)
- Sabre grind (a subtype of the “V” grind - also called a “Scandinavian” or “Scandi” grind)
- Chisel or single bevel grind*
- Double bevel or compound bevel*
- Convex grind
(* The grinds most popularly found in kitchen knives)
I’ll focus a little more on the three grinds more commonly found in kitchen knives - flat, chisel, and double/compound.
Just so you know, generally Western kitchen knives have a double-bevel (20-22° on both sides or sometimes 15° on the first bevel and 20–22° on the second), while Asian kitchen knives are made of harder steel and are ground at 15–18°, being either double-ground or (quite often) chisel-shaped (single-ground). More about all that in a sec.
Flat or “V”
A full flat ground blade typically refers to blades that form a classic “V” shape, where both sides taper toward each other at a consistent angle until they meet. Most knives you come across will probably have this "V" angle. The edge tapers equally from both sides of the blade.
The Full Flat Grind begins tapering to the edge from the spine evenly on both sides. This means the edge is extremely sharp, but it's not as durable. It’s great for pushing the knife into things - which makes it very popular for chef knives.
Knives manufactured in the Western tradition are typically ground with a 20 to 22 degree edge angle. Which means that the actual knife (the inclusive angle) is cutting with a 40-44° wedge. It's less sharp than the single/chisel bevel (below), but is pretty sharp and holds it's edge much better.
Chisel or Single Bevel
Chisel ground blades are exactly what you think they are, chisel shaped. Only one side is ground; the other remains flat. The flat side of the blade helps separate slices of food being cut.
Japanese knives are ground with edges from 10– 15° (or included angles of 20 – 30°). These babies are SHARP! But, they also can require much more maintenance.
Knives which are chisel ground can come in left and right-handed varieties, depending upon which side is ground.
Here's where things can get a little confusing (ok, more confusing). Different people use the same words to say different things. Some people use the term "double bevel" to mean that the knife is sharpened on both sides -- which is really a "V" edge (like I described above). Others use the term (to me, more accurate) to mean that each side of the knife has two different angles (like in the picture to the right).
The grind starts from the spine of the knife, then gets sharper (primary bevel) and then even sharper or a more acute angle at the edge (secondary bevel). This provides a stronger more durable edge, but with a little less sharpness. There's always a trade-off, right?
Being less acute at the edge than a single bevel, the double bevel sacrifices a little sharpness for resilience: it's much less prone to chipping or rolling than a single bevel blade. Western kitchen knives with a double bevel have an edge angle of 20-22° (inclusive angle of 40-44°).
Another key aspect of a knife blade to consider is the edge finish. This one is a lot simpler to understand (and easier to tell apart). There are essentially two edges - a straight edge that’s used for chopping or slicing (like most knives such as chef knives, etc.) or a serrated edge that’s used more for sawing. You’ll see the serrated ones more often on bread knives and tomato knives. The teeth of these knives grab the outer part of the food (bread crust, peel of a tomato) and cut through the food without crushing it like a straight, smooth edge would. These knives are ground on one side only, which makes them very sharp.
Those are the main things you need to know. Go take a look at your kitchen knives. See if you can identify which one(s) you have. I hope you have found this info helpful as you get to know your knives better!
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