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Knives must be sharp to perform to their full potential, but sharpening must be performed correctly for the knife to work as intended. How do you know when you should sharpen both sides of a knife and when you only need to sharpen one side?
Single-bevel knives must only be sharpened on one side, while double-bevel knives must be sharpened on both sides. Incorrectly sharpening knives can ruin the knife’s edge and require extensive repair work to restore the blade geometry for precision sharpness.
The edge geometry of the cutting edge of a knife is an important aspect of its sharpness. We will discuss the difference between single and double-bevel knives and how it affects sharpening to demystify this topic and provide a clear understanding. We will detail the advantages and disadvantages of each type of edge and the debate around sharpening both sides.
Is It Necessary To Sharpen Both Sides Of A Knife?
The necessity to sharpen one or both sides of a knife is not a choice but is determined by the blade’s edge geometry.
It is important for knife owners to know what type of edge their knife has and the type and technique of sharpening required to retain the edge’s integrity and keep it as sharp as possible.
Understanding bevel types on a knife blade is necessary to know which sides of your knife need sharpening.
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What Sides On A Single Bevel Knife Need Sharpening?
A single-bevel knife, also known as a chisel grind knife, is a knife that has a single beveled edge, meaning it is sharpened on only one side.
One side of the knife, often called the back side, is flat, with no taper on the blade towards the cutting edge. The opposite side of the knife is ground to form a taper, or bevel, from the spine to the cutting edge.
This type of bevel or edge geometry is commonly used in traditional Japanese knives and is particularly popular because of the fine, accurate cutting required for slicing fish and other delicate ingredients.
Single-bevel knives have several distinct characteristics.
- Enhanced sharpness. The edge is angled on one side only, which creates a sharper cutting edge than a double-bevel knife.
- Thinner blade. The blade is usually thinner and lighter than a double-bevel knife, allowing for more cutting precision.
- Precise cuts. The flat side of the blade and the thinness of the blade promotes precise, accurate cuts, often necessary for preparing cuisine where aesthetics are important.
- Less durable. Single bevel blades are usually made from very hard steel for the edge to stand up to normal use. Single-bevel edges are considered less durable than double-bevels due to less material on the blade’s fine edge.
While single-bevel knives offer some advantages, they also have some disadvantages. For example, they can be more difficult to sharpen than double-bevel knives because they require a specific angle to maintain the bevel and prevent over-sharpening, which can ruin the edge.
The single-bevel design can cause the blade to pull to one side during a cut, making it more challenging to use for certain cutting tasks.
Single-bevel knives are also hand dominant specific, meaning that if you are left-handed, you need a single-bevel knife designed for a left-handed person. If you are right-handed, the blade bevel must be designed for use in the right hand.
A right-handed single-bevel knife will have the flat side of the blade on the left side of the blade, and a left-handed single-bevel knife will have the flat side on the right of the blade.
When sharpening a single bevel knife, it’s important to use the correct technique to ensure that the angle of the bevel is maintained. The beveled side of a single-bevel knife is the edge that must be sharpened.
The flat edge of a single-bevel knife is often not completely flat, especially in Japanese single-bevel knives. The flat edge has a slight concave grind above the cutting edge, making sharpening these knives more difficult.
The flat side of the blade does not require sharpening, but it does require stropping or honing to remove the burr created by sharpening the beveled side.
Once a knife has been created as a single-bevel knife, it must always only be sharpened on one side and cannot be converted to a double-bevel. Sharpening a single bevel on both sides will ruin the edge and may require the need for extensive repair work on the edge to restore the edge geometry.
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What Sides On A Double Bevel Knife Need Sharpening?
A double-bevel knife, also known as a Western-style knife, has a beveled edge on both sides of the blade, allowing for a symmetrical cutting edge.
This type of knife is commonly used in Western cuisine and is popular for a wide range of cutting tasks, from chopping vegetables to slicing meats. Many Japanese knife makers have adopted this edge geometry to cater to the Western market.
The blade is ground to form a taper from the spine to the sharp cutting edge on both sides of the blade. There is no flat side on one of these knives, and the grind on both sides provides symmetry to the blade profile.
The characteristics of double-bevel knives are as follows.
- Durable edge. The edge is sharpened on both sides, which creates a more durable cutting edge than a single bevel knife.
- Thicker blade. The blade is often thicker and heavier than a single bevel knife, making it ideal for heavier-duty tasks.
- Ambidextrous use. The symmetrical design of the blade allows for more versatility in cutting, as the knife can be used comfortably in either hand.
- Easier to sharpen. Double-bevel knives are easier to sharpen, making them popular as a general knife choice.
While double-bevel knives offer some advantages, they also have some disadvantages. For example, the symmetrical design of the blade can make it less precise than a single bevel knife, limiting the sharpness of the edge.
When sharpening a double-bevel knife, it’s important to sharpen the blade on both sides to ensure symmetry and sharpness.
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Can You Sharpen The Knife’s Spine?
The spine of a knife is the upper edge of the blade. Typically, this side of the blade is not sharpened, except in knives with specific blade designs.
Many outdoorsmen or survivalists use the spine of their bushcraft knives to strike Ferro rods or scrape kindling from branches for fire-making techniques. The knife’s spine must be a 90° edge to enable the knife to be used in this way.
If the bushcraft knife does not have a 90° edge on the spine, people often grind the spine square so the knife can function for this purpose.
Some knives are designed to have a sharp edge on the upper and lower side of the knife. These knives are called daggers and are usually used in combat roles by the military. In some regions, it is illegal to carry daggers because of the intended purpose of these knives.
Daggers are generally double-bevel knives and must be sharpened on both sides of the blade as well as the top and bottom edges.
Single-bevel knives should only be sharpened on the beveled side, while double-bevel knives must be sharpened on both sides. The blade geometry must be followed, and appropriate sharpening techniques must be applied to attain optimal sharpness on the cutting edge.
Regular maintenance, including honing and sharpening, will help extend your knife’s life and ensure that it performs at its best, but the knife must be sharpened correctly. Learning to sharpen your own knives is rewarding but requires some knowledge and understanding of the blade design.
TIP: It is possible to get carried away and oversharpen a knife. To find out the potential issues with this problem read our article on the topic!
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