How do you know how long your knife will last? How “strong” or “solid” is it? How do you tell what separates the first-class Scrimshaw Pocket blade from just a beautiful blade that breaks faster than you can cook a week’s worth of dinners? Here, scientific measurement tactics come to the rescue, namely, the Rockwell hardness scale.
With so many different blade options, from carbon steel to various types of stainless steel and Scrimshaw Pocket knives, it can be difficult to determine which material is best for your purposes. So it’s worth spending some time researching this topic so that the next time you plan on buying a knife, you’ll know exactly how to check it out.
So what makes a quality kitchen knife?
- When talking about the qualities of steel for blades, classically they mean its hardness, strength, wear resistance, and ability to hold the blade. These terms can be a bit confusing, so let’s define some definitions.
- Hardness is a measure of resistance to kinks, chips, and other deformations when force is applied.
- Edge retention refers to how long a blade keeps its edge sharp.
Both strength and wear resistance are classified as durability. Not to be confused with hardness, toughness is a measure of how well a knife can withstand heavy use before cracking or chipping. There is a general rule: the harder the steel, the less strong it will be.
Corrosion resistance refers to the ability of a blade to resist chemical or elemental degradation such as rust.
But the combination of all these qualities in one knife does not mean that it will be the best. It has its characteristics: you sacrifice hardness for strength and vice versa.
Now that we have dealt with the properties of a knife, let’s focus on blade hardness and its measurement using the Rockwell scale.
What is the Rockwell hardness scale?
The Rockwell hardness scale is a 1900s invention by eponymous craftsmen. This is a hardness tester that shows the dependence of the measurement of the hardness of material on the pressure that must be exerted to leave an imprint on its surface.
After several years of testing the effectiveness of the scale, today there are variations of it. For example, type A testers for tungsten carbide materials, type B testers for brass and aluminum, and type C testers for hard steel materials. When it comes to testing kitchen knife steel, hardness is a combination of a blade’s strength and how well it holds a sharp edge. And the harder the steel, the more wear resistance it has.
How to Read the Rockwell Hardness Scale
If you have ever studied the characteristics of a knife, you may have noticed several letters followed by numbers and symbols.
Keeping in mind that there are several types of Rockwell hardness scales – type A, B, C, etc., we take into account the fact that each of them uses different loads depending on the material being tested. Type C is used to measure metal materials for kitchen cutlery and is always referred to as HRC followed by its hardness rating.
The test is run more than once to determine the average rating and confirm accuracy. Typically, Type C values for kitchen knives range from 52 to 61. Therefore, the measurement will be somewhere between HRC52-HRC61, although slightly larger variations are possible.
So, the Rockwell hardness scale indicates how strong the blade of any particular kitchen knife is, and this number is often stamped or printed on the blade or handle.
How should a kitchen knife be classified?
When it comes to kitchen knives, the HRC rating can make or break a blade. At the bottom of the scale (around 52), you will see a very soft blade that will probably be easy to sharpen but will need to be sharpened often due to its inability to hold the blade. At a higher level (above HRC62) you will get a super hard but very brittle blade that breaks easily on impact.
Therefore, the best option would be high-quality kitchen knives with an HRC rating of 58 to 61. For example, a Kanetsugu Saiun Damascus utility knife with a blade hardness of 60-61.
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