What Style of Knife Do I Have?
There are many different types of knives currently in use around the world, each with their own unique properties and uses. This page will briefly cover the most common blade styles from the perspective of sharpening, to help you select the proper sharpening style for your blade.
In general, blade styles are defined by two measures. The blade's geometry and the blade's profile. These two measures determine both the functional characteristics of the knife and what techniques must be used to sharpen it properly.
Blade Geometry
A blade's geometry is determined by the shape of a cross section of the blade, which can be viewed by looking at a knife along the length of it's blade with the tip towards you. A blade's geometry is also commonly referred to as its "grind". The geometry of a blade is oftentimes the most important feature for sharpening, as this is what differentiates styles such as Western, Japanese and Scandinavian. These in turn determine how the knife must be sharpened. Below we will discuss some common blade geometries you may run into and their purpose.
Western Styles
The western style is by far the most commonly used style in the United States and European countries. It is also very common in the rest of the world to varying degrees. A Western style knife can essentially be considered any knife with a symmetrical cross section and a small secondary bevel that forms the cutting edge. Western style knives, due to their symmetrical nature, are generally the easiest to sharpen and least specialized in their range of function. These two features are the reason for the prevalence of this style of knife around the world. Due to their ubiquitous nature, many grind geometries have been developed in this category, including the above listed Full Flat, High Flat, Double Bevel, Sabre, Hollow, Full Hollow and Convex grinds.
The Full Flat Grind
Probably the most basic of knife grinds, the full flat grind is essentially a triangle, with a secondary bevel forming the cutting edge. This grind, depending on how it is executed, can create anything from a fine slicing edge to a fairly strong chopping edge. Due to its versatility and ease of manufacture, this grind can be found in many knives. It is especially prevalent in kitchen knives, which almost always feature full flat grinds for fine slicing work. It can also be found in virtually every other category of knife to varying degrees.
The Double Bevel, High Flat and Sabre Grinds
These three grinds are all variations on the same theme. All three are essentially a full flat grind, which begins partway between the spine and the edge, leaving a flat area towards the spine of the blade. The purpose of this flat area being to provide more strength to the blade by removing less steel than a Full Flat grind. The difference between the three is how close to the edge the flat grind starts. A Sabre grind for instance starts closer to the edge than the spine, leaving a large flat area to provide extra strength to the blade. A High Flat is the other end of the spectrum and starts closer to the spine, creating a smaller flat area and finer edge, more suitable for slicing. These grinds provide a happy medium between fine slicing ability and strength and are thereby used mostly on knives which may see a wide variety of uses. These grinds - the high flat in particular - are very common and can be found in many multipurpose knives such and pocket knives, hunting knives, fighting knives and survival knives.
The Hollow and Full Hollow Grinds
A Full Hollow grind is created by grinding the blade on a round wheel. This creates a blade which is concave on both sides, from the spine to the edge, where a small secondary bevel creates the actual cutting edge. The relationship between the Hollow grind and Full Hollow grind, is the same as the relationship of the High Flat grind and the Full Flat grind. In a Hollow grind, the "hollow" part of the blade starts partway between the spine and the edge, adding strength to the blade. Both of these grinds create a very thin, fine edge, which is surpassed only by some Japanese style blades in slicing ability. This results in it also being the weakest of common grinds and prone to damage from hard use. Due to their fine slicing performance, Hollow and Full Hollow grinds dominate straight razor designs. They also find some use in a variety of other knives including hunting and camp knives.
The Convex Grind
The convex grind is, in every way, the opposite of the Full Hollow grind. It is created using a belt grinder with no support behind the belt so that the belt flexes around the blade. This creates a blade in which the sides are convex and the cross section resembles an ogive. The sides of a convex blade form a continuous curve from the spine through to the cutting edge. Unlike other western style grinds, there is no flat secondary bevel at the cutting edge. This forms a very beefy, strong edge, not intended for fine slicing. Convex grinds are found almost exclusively on axes, hatchets and heavy chopping knives and see virtually no use in everyday knife designs.
The Japanese Style
The Japanese style predictably originates in Japan and therefore is most popular in the Orient and comparatively rare in western countries. The exception to this perhaps being in traditional Japanese restaurants and kitchens around the world.
The Japanese Single Bevel
Traditionally, Japanese knives are flat on one side (usually the left) and bevelled or hollow ground on the other, with a cross section resembling one side of an equivalent western style grind. Often these knives are actually hollow ground on the "flat" side as well, but in parallel to the centerline of the blade making them effectively flat. For the purpose of this text however we will refer to this side as the "flat" side. Due to this asymmetric shape, Japanese single bevel knives are not ambidextrous like Western and Scandinavian style knives. When used in the wrong hand, they will tend to drift and turn in the direction of the flat side while slicing. Left handed knives are extremely hard to find and often times have to be custom ordered. The benefit of this design however, combined with the already thinner design of Japanese style knives, is that they can be made extremely sharp compared to most western knives of similar use. This lends to the fine, intricate cutting styles of traditional Japanese cuisine. Japanese Single Bevel knives are also usually designed for specific purposes, such as preparing sashimi or slicing vegetables, making it more important to have the right knife for a given task. Japanese Single Bevel knives are sharpened on only one side and care must be taken not to remove any more material than necessary from the flat side of the knife. Improper sharpening will result in either a knife that doesn't slice as well as it should, a knife that turns sideways as you slice, or both.
The Japanese Double Bevel
Also known as Japanese Western knives, this design is a more recent innovation and stems from the increased European and Western influence in Japan following World War II. After the war, more western knives and western foods were introduced into the Japanese culture. Fine, purpose-built, Single Bevel knives, however, could not provide a wide enough range of use to deal with these changes. So Japanese manufacturers took a page from the western book on knife making and began creating knives that were bevelled on both sides. At first glance, it seems this would create a knife no different from any western style knife. This is not the case however, since these manufacturers didn't entirely dismiss their traditional, asymmetrical Japanese style. The defining difference between Western Style and Japanese Double Bevel knives is that Japanese Double Bevel knives are ground more on one side than the other, creating an asymmetrical blade cross section. This makes Japanese Double Bevel Knives among the hardest to sharpen because, unlike Single Bevel knives which are sharpened on only one side, Japanese Double Bevel knives are sharpened on both sides, but must be sharpened more on one side than the other, depending on how asymmetrically they're designed. This style is a compromise between the versatility of Western Style knives and the fine slicing capability of Japanese Single Bevel knives. Their asymmetric design means however that this grind is not ambidextrous and thereby suffers the same shortage of left handed knives as the Japanese Single Bevel style.
The Scandinavian Style
The Scandinavian Style consists of only one blade grind and thereby is more
commonly known simply as the Scandinavian Grind. Commonly
called the Scandi or V grind, it originated in the Nordic countries
as a multipurpose camp and bush knife and has since gained some degree of
popularity around the world. This grind is very similar to the Sabre grind
discussed above, the only difference being that there is no small secondary
bevel added to create a cutting edge. Due to its great similarity to the
Sabre grind, it can actually be transformed into a Sabre grind during
sharpening by simply adding a small "micro bevel" to the edge. This can be
done intentionally, or can be the result of an improper sharpening technique.
The proper and traditional method to sharpen the Scandinavian grind
however, is to grind the entire surface of the bevel on a flat stone, with great
care being taken to not deviate from the original angle of the bevel, as this
will result in poor edge quality, unsightly marring of the bevel, or both. This
grind results in a strong, yet extremely sharp blade, capable of taking a good deal of abuse. Due to the rapid increase in the width of the edge and often thick nature of this style of blade however, its slicing performance through thicker materials is often diminished. As a result of these attributes, this grind mostly sees use in bushcraft, outdoor and especially in woodworking knives.
Blade Profiles
A blade's profile is the shape of the blade when looking at it from the side. There are dozens, if not hundreds of blade profiles in existence, with a few common ones including the drop point, clip point, tanto, reversed tanto, sheepsfoot, recurve, spearpoint and others. However the only profiles of consequence to sharpening are the ones that define the shape of the cutting edge. These usually fall in one of three categories.
The first and most common is a normal plain edge blade. This category includes everything from kitchen knives to Bowie knives. This is the most basic edge profile and can be sharpened using a number of different tools and techniques.
The second is the recurve. In a recurve blade the edge of the blade and oftentimes the entire blade sweeps downwards as you approach the tip of the blade. A good example of a recurve knife is the kukri style chopping knife. Recurve blades also find their way into pocket knives, hunting knives and just about every other category of knife, except perhaps kitchen knives. Recurves must be sharpened on either belted or rounded tools in order to evenly sharpen the inside radius of the edge without marring it.
The final category is serrated knives, which can essentially be defined as any knife with a series of alternating teeth and "valleys" called gullets along the cutting edge. Serrations are the hardest to sharpen because they must be sharpened by thin rounded hand tools, as no other sharpening tool can grind the insides of the gullets of the serrations.
