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Advice and Theory on Sharpening Angles for Knives

We have found that many customers really want to know more about selecting the angle for their knife. In this article we will discuss in more detail why you may want to choose one angle over another.

Double-bevel edge showing 20+20=40Before getting into the detail, we’d like to make it clear how we talk about the angles on a knife. Most knives have a bevel on both sides. When we tell someone that they should put a 20 degree angle on a knife, we mean that they should sharpen each side to 20 degrees. This creates a total angle of 40 degrees. So when we’re talking about the angle on your knife, we’re talking about the angle at which you hold the knife to your stone.

The difference between a double and single bevel knife edgeThere are special cases where the total angle of the knife is not double the angle that you sharpen each side of your knife. Some traditional Asian knives are only beveled on one side. In this example, one side may be sharpened to 20 degrees while the other side is at 0 degrees for a total angle of 20. However, in practice, we have found that the vast majority of Asian knives sold in the United States are not single bevel but rather traditional knives with a bevel on both sides. If you’re not sure, it is generally safe to assume that your knife has a bevel on both sides. Asian knives do typically have a slightly lower angle and both sides are sharpened to roughly 17 degrees.

Choosing an angle to sharpen your knife is essentially a compromise between the sharpness and the durability of an edge. The most important factor when determining the angle comes down to how you will be using your knife. Will you be shaving your face, filleting a fish, cutting vegetables, carving or chopping wood? From these examples, it is easy to see how each case requires a different edge.

Hardness vs. Toughness

Many people enjoy having a very high quality knife and appreciate good steels. Regardless of the steel, certain facts of steel hardness still apply. The hardness of steel is very easy to understand and is measured on a scale called the Rockwell C Scale. The toughness in metallurgy is the material’s ability to withstand fracture. A simple example of a material that is very hard but not tough is glass. Given the same knife, making it harder will reduce its toughness. When a knife maker heat treats steel, they must strike a balance between hardness and toughness. Too hard and it could break easily, too soft and it won’t hold an edge. The compromise between hardness and toughness in knife making is very similar to the compromise in choosing a sharpening angle.

Under 10 Degree Angles

The lowest angles are reserved for edges that are typically cutting softer materials. In this case, the edges are not subject to abuse so the lower angle can be maintained without damage or edge failure. The lowest angles that we typically see are on straight edge razors. These are sharpened to an angle that is roughly 7 to 8 degrees (although the back of the blade is used as a guide so knowing the angle isn’t important and it is not adjustable). A straight razor has a very delicate edge that is very easy to damage. In proper usage, a straight razor would never see the type of use that would damage the edge.

If you’re sharpening straight razors at these low angles, water stones are going to be the most effective way to sharpen. With delicate edges on straight razors, we generally don’t recommend anything coarser than 1000 grit.

10 to 15 Degree Angles

A sharpening angle of 10 to 15 degrees is rather low for most knives. With a total angle of 20 to 30 degrees, this edge is very fine and more delicate. This edge is typically too weak for any knife that might be used in any type of chopping motion. Also, consider that harder steels are also more susceptible to impact damage because they are more brittle. If your knife is used for cutting soft items or slicing meats, this lower angle can hold up and provide a very smooth cutting action.

In the last decade, Japanese knives at the higher end of this range (roughly 15 degrees) have become quite popular. These knives tend to use quality steel that is harder. When sharpening these knives, we generally recommend sharpening stones as they’re able to able to cut the steel without being too aggressive. The traditional stone for sharpening Japanese knives is the water stone and so that is what we often recommend.

15 to 17 Degree Angles

A sharpening angle of 15 to 17 degrees is where many Japanese knives and newer European/American cutlery is sharpened from the factory. With a total angle of 30 to 34 degrees, this edge will cut a little easier than edges with greater angles. This is the lowest angle we generally recommend for most knives that we designed with an original angle of 20 degrees. The tradeoff when using this lower angle is durability.

We have many different sharpeners that can sharpen to this angle. Many of our powered sharpeners, sharpening stones, or guided systems are appropriate for these angles.

17 to 22 Degree Angles

A 17 to 20 degree angle covers most kitchen knives, pocket knives, and outdoor knives. Some knives (typically Japanese manufacturers) will sharpen their knives to roughly 17 degrees. Most western knives are roughly 20 degrees. In fact, a 20 degrees angle is often considered the best sharing point for most knives. It is our experience that kitchen knives sharpened to 17 to 20 degrees cut very well and are still durable. For pocket or outdoor knives, a 20 degree angle would be on the low side of ideal. These angles are a good tradeoff between sharpness and durability.

We have many different sharpeners that can sharpen to this angle. Many of our powered sharpeners, sharpening stones, or guided systems are appropriate for these angles.

22 to 30 Degree Angles

In this range, the knife edges are considerably more durable. A pocket knife or a hunting knife will inevitably see abuse not seen by knives meant primarily for slicing or chopping softer materials. While the edge may not ultimately cut as well (but you may not notice a difference) it will be considerably more durable.

We have many different sharpeners that can sharpen to this angle. Many of our powered sharpeners, sharpening stones, or guided systems are appropriate for these angles.

Over 30 Degree Angles

Any edged tool or knife that is sharpened past 30 degrees will be very durable. Its cutting ability will be noticeably reduced. This durability has an advantage because more force can be used to make the cut. While the majority of knives won’t benefit from this sharpening angle, an edged tool like a machete, cleaver or axe must be durable (and can be made of softer steel) and can respond to a 30 degree angle.

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