How to Test Knife Sharpness (with video)

Knife on a Table
Knife on a Table

When it comes to cooking, having a sharp knife is essential. Not only does it make your job easier, but it also ensures that you can cut through meat, vegetables, and other ingredients with ease. However, it can be difficult to tell if your knife is sharp or not. In this article, we will show you how to test your knife’s sharpness so that you can always be sure that you are working with a sharp blade.

By knowing how to test your knife’s sharpness, you can ensure that you are always working with a sharp blade. Not only will this make your job easier, but it will also help to prevent accidents in the kitchen. So, whether you are a professional chef or a home cook, make sure to test your knife’s sharpness on a regular basis.

Understanding Knife Sharpness

When it comes to knives, sharpness is essential. A sharp knife makes cutting and slicing easier and more efficient. However, it can be challenging to determine if your knife is sharp enough for the task at hand. Here are some things to keep in mind when testing knife sharpness:

The Sharpness Scale

Knife sharpness is measured on a scale of 1 to 5, with 1 being the least sharp and 5 being the sharpest. A knife that is rated 1 is considered dull and won’t cut through anything. A knife rated 5 is razor-sharp and can cut through almost anything effortlessly. Most knives fall somewhere in between these two extremes.

Factors That Affect Sharpness

Several factors can affect the sharpness of a knife. The type of steel used to make the blade, the angle of the edge, and the honing method all play a role in determining how sharp a knife is. Additionally, how often you use your knife and how you store it can also affect its sharpness.

The Paper Test

One of the most popular and reliable ways to test the sharpness of your knife is the paper test. This test is easy to perform and requires only a piece of paper and your knife. Here’s how to do it:

Performing the Paper Test

  1. Take a piece of paper and hold it vertically in front of you with one hand.
  2. With your other hand, hold the knife blade against the top edge of the paper.
  3. Slowly and gently draw the blade down the paper, slicing through it from top to bottom.
  4. If the knife is sharp, it should slice through the paper cleanly and effortlessly.
  5. If the knife is dull, it will tear the paper or leave a jagged edge.

It’s important to note that the paper test is not foolproof and may not always accurately determine the sharpness of your knife. For example, a serrated knife may not perform well on the paper test, even if it is sharp. Additionally, the type of paper used can also affect the results of the test.

To get the most accurate results, use a piece of printer or copy paper, which is thin and easy to slice through. You can also try the paper test with different types of paper to see how your knife performs on each one.

The Tomato Test

When it comes to testing the sharpness of your knife, one of the most popular methods is the tomato test. This test involves using a tomato to see how easily the knife can slice through it. A sharp knife should be able to slice through a tomato with minimal effort, leaving clean and even cuts. If the knife struggles to cut through the tomato or if the cuts are uneven, it’s time to sharpen your knife.

Conducting the Tomato Test

To conduct the tomato test, follow these simple steps:

  1. Select a ripe tomato and cut off one end to create a flat surface.
  2. Place the tomato on a cutting board with the flat end facing down.
  3. Hold the tomato in place with one hand and use the other hand to slice through the tomato with your knife.
  4. The goal is to cut the thinnest and cleanest slice from the tomato without holding onto the tomato or applying much pressure with your knife.

If your knife is sharp enough, it should slice through the tomato with ease. You should be able to cut clean and even slices without squishing the tomato. If you find that your knife is struggling to cut through the tomato or if the slices are uneven, it’s time to sharpen your knife.

The Onion Test

When it comes to testing the sharpness of your knife, the onion test is a classic and reliable method. This test is simple and easy to execute, requiring only an onion and a sharp knife. Here’s how to do it:

Executing the Onion Test

  1. Cut off the top of an onion.
  2. Slice the onion in half from top to bottom.
  3. Hold one of the onion halves flat on the cutting board.
  4. With the blade of your knife at a 45-degree angle, slice through the onion from the root to the tip.
  5. Repeat the process on the other half of the onion.

If your knife is sharp, it should slice through the onion smoothly and cleanly, without crushing or tearing it. The onion should remain intact and not fall apart. If your knife is dull, it will crush the onion, and the slices will be uneven and ragged.

The onion test is a great way to test the sharpness of your knife because onions have a delicate structure that requires a sharp blade to slice through cleanly. Plus, onions are readily available in most kitchens, making this test easy to perform at home.

Professional Sharpness Testing Tools

If you’re a professional sharpener, woodworker, or knife enthusiast, you might want to consider using a professional sharpness testing tool to evaluate and compare edges accurately. Here’s a breakdown of how to use one:

Using a Sharpness Tester

One popular tool is the Edge-On-Up Pro Edge Tester (PT50B), which features a 10 measurements-per-second processor, 5-gram resolution, and a portable lightweight design. To use this tool, follow these steps:

  1. Turn on the sharpness tester and wait for it to calibrate.
  2. Place the blade on the testing surface and apply slight pressure.
  3. The tester will give you a reading in grams, indicating the force required to cut through the material.

The Edge-On-Up Pro Edge Tester uses the BESS (Brubacher Edge Sharpness Scale) standard to determine the sharpness of knives. Developed by Mike Brubacher, owner of Edge-On-Up, this scale is widely used in the industry.

Another popular tool is the CATRA (Cutlery and Allied Trades Research Association) tester, which measures the sharpness of blades using a rotating abrasive wheel. This tool is more expensive than the Edge-On-Up Pro Edge Tester but is more accurate and consistent.

Maintaining Knife Sharpness

Keeping your knives sharp is essential for efficient and safe cutting. In this section, we will discuss the three key steps to maintaining knife sharpness: proper storage, regular honing, and timely professional sharpening.

Proper Knife Storage

Storing your knives properly is crucial to prevent them from dulling prematurely. Here are some tips to keep in mind:

  • Store your knives in a knife block, magnetic strip, or sheath to protect the blade from damage.
  • Avoid storing your knives in a drawer or with other utensils that can scratch the blade.
  • Clean and dry your knives before storing them to prevent rust and corrosion.

Regular Honing

Honing your knife regularly will help maintain its sharpness and prolong its lifespan. Here’s how to do it:

  • Use a honing steel or ceramic rod to realign the blade’s edge.
  • Hold the honing steel at a 20-degree angle and draw the blade towards you, from the heel to the tip, using light pressure.
  • Repeat on the other side of the blade, alternating sides until you’ve honed each side three to four times.

Timely Professional Sharpening

While honing can help maintain a knife’s sharpness, it won’t sharpen a dull blade. That’s where professional sharpening comes in. Here’s what you need to know:

  • Don’t wait until your knife is completely dull to have it sharpened. Regular sharpening will help prolong the knife’s lifespan.
  • Look for a reputable professional sharpener who uses the right equipment and techniques for your type of knife.
  • Consider the frequency of use and the type of cutting you do when deciding how often to have your knives professionally sharpened.

By following these three steps, you can maintain your knives’ sharpness and keep them in top condition for years to come.

Frequently Asked Questions

What is the Edge-On-Up sharpness tester?

The Edge-On-Up sharpness tester is a tool designed to measure the sharpness of a knife. It works by measuring the force required to cut through a standardized material, such as cardboard or rope. The lower the force required, the sharper the knife.

How do I know if my knife is 15 or 20 degree?

The angle of a knife’s edge is typically measured in degrees. A 15-degree angle is sharper than a 20-degree angle. To determine the angle of your knife, you can use a protractor or angle gauge. Alternatively, you can check the manufacturer’s specifications or contact the manufacturer directly.

How sharp should a pocket knife be?

The sharpness of a pocket knife depends on its intended use. A knife used for slicing food should be very sharp, while a knife used for cutting rope or cardboard may not need to be as sharp. As a general rule, a pocket knife should be sharp enough to cut through its intended material with minimal effort.

Is there a scale for sharpness?

There are several scales used to measure the sharpness of a knife, including the Rockwell scale and the Vickers scale. These scales measure the hardness of the blade material, which is related to its ability to hold a sharp edge. However, there is no universal scale for sharpness that applies to all knives.

How are knives tested?

Knives are tested using a variety of methods, including the paper test, the Edge-On-Up test, and the CATRA test. These tests measure the knife’s ability to cut through various materials, such as paper, cardboard, and rope. Manufacturers may also test their knives using specialized equipment and techniques to ensure consistent quality and performance.

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