A sharp knife is an asset in almost any situation. But are there circumstances in which a knife can be too sharp?
This article looks at where a knife’s sharpness is definitely an asset…or can be detrimental.
How Sharp Should a Knife Be?
A knife should be sharp enough to cut smoothly through its designated target with minimal resistance and clean cuts.
On the other hand, an inexperienced user can make a sharp knife a hazard. And if you need reasonable control, a very sharp blade can make precision and careful handling more difficult.
Experts say every knife has a ‘sweet spot’, the perfect level of sharpness for proper handling. Another professional opinion is that a knife should have a blade of the sharpness and shape best suited to the task at hand.
What Are The Risks of a Knife That’s Not As Sharp?
Some advocates say that a dull knife is better for inexperienced handlers, who inadvertently risk cutting themselves on a sharper edge. Others, however, point out that a dull knife can be even more dangerous.
Duller knives often require more force and effort to use. This can result in exerting too much force and causing the blade to slip.
Many kitchen accidents happen when a user applies an improperly sharpened knife to a task. The user winds up using too much force or employing a sawing motion to cut through, and the knife or the user’s hand slips.
Does Dullness Have a Use?
It depends on the definition of ‘dullness’. A knife on which the metal is worn down or damaged is a ‘dulled’ knife.
A knife with a worn or dulled edge is not helpful. In fact, it can be dangerous.
However, a knife can also have what experts call a ‘dull’ or ‘obtuse’ edge, where the metal has been sharpened at a wider angle. These wider edges can actually have a benefit in certain circumstances.
What Can You Use a Knife with a ‘Dull’ or ‘Obtuse’ Edge?
The more obtuse the edge – the more robust – the sturdier the knife. And a sturdy knife can do things that a slimmer knife cannot. For example, a butcher knife is likely to have a more robust edge than a paring knife.
Likewise, a camp or survival knife might need a stronger edge to perform the multitude of tasks it might be required for.
Any Other Uses for an Obtuse Edge?
An obtuse edge is naturally more durable. Even a finely edged knife can be used with a slightly thicker edge.
Too fine an edge becomes brittle and easily damaged. In addition, it can be chipped or rolled, making it harder to sharpen again.
Keeping an edge at a slightly ‘duller’ edge can help it last longer and require fewer sessions of honing and sharpening.
How Do I Know What Kind of Edge a Knife Needs?
In some situations, it requires experience. For example, there are several types of kitchen knives, and each might need a different fineness of edge.
There are a few guidelines:
A larger, heavier knife often needs a more robust edge. The weight of a larger blade is likely to damage a finer edge.
Like a paring knife or a Japanese Sashimi knife, a small, slender blade can take a much finer edge.
Serration of the blade is also a factor. A serrated knife works differently than a smooth blade.
Single or double bevels also make a difference in how fine the edge can be ground.
How Does Serration Affect the Edge of the Blade?
With a serrated blade, the blade’s serrations do most of the work that an edge would do on a regular knife.
A serrated edge can be more obtuse than a smooth edge and still cut as well. Likewise, it can be finer than a smooth edge and still last longer.
How Does the Bevel Change the Edge of the Blade?
A single bevel on a knife can allow for a sharper angle without the brittleness this would typically cause.
Most Japanese knives have a single bevel, which allows them to have the thinner, sharper edge they are known for.
The double bevel requires a thicker angle. Because the bevel is on both sides, the angle becomes double of a single bevel angle. That’s why the angle on a double bevel is usually somewhere around 30 degrees.
What Angles Should a Blade be Sharpened to?
Different blades should be sharpened to different angles.
Experts tend to agree that the angle of an edge should never be less than 10 degrees.
Finer than 10 degrees results in a too fine blade to sustain much use.
Most experts agree that even the most heavy-duty and robust blades shouldn’t have an edge with an angle over about 35 degrees. An edge with an angle greater than 35 degrees may not be sharp enough to cut properly.
What Are The Recommended Angles For Different Types of Blades?
Japanese knives are usually ground to about 10-15 degrees.
Most regular cutlery takes an edge of 20-25 degrees.
Cleavers, Butcher knives and Machetes usually take an edge of 30-35 degrees.
The recommended edge angle is 25-30 degrees for survival knives, hunting knives, and pocket knives.
How Do I Know What Angle My Knife Edge is Ground To?
There are knife grinders set at specific angles. You can use these to measure the angle of the bevels.
These will also help you keep consistent angles ground. Hand grinding often makes it difficult to maintain an accurate angle on the edge.
The downside is that if you’re not careful, you can grind too steep or too flat.
Some experts recommend using what they call the ‘Sharpie Trick’.
What is the Sharpie Trick?
Take the knife and coat both bevels with Sharpie ink.
Put the knife in a grinder with a set angle and pass it through the sharpener a few times.
Check the Sharpie coating.
If the Sharpie is scrapped only off the top of the bevel, the angle of the grind is too steep.
If the Sharpie is ground only off the bottom of the edge, the grind is too flat.
Continue adjusting until it takes the Sharpie off cleanly.
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