The Rockwell hardness scale is used to measure the hardness of materials, including metals and steels, and is named after its inventor, Stanley Rockwell. The scale is based on measuring the depth of the impression of a test tip in a material under a certain load.
The Rockwell scale is numerical, with values usually designated as HRC (Rockwell C), the most common scale for steels used in the cutlery industry. This scale measures the hardness of steel between 20 and 70 HRC. A higher value means harder steel.
The process of measuring hardness involves creating a small hole using a test tip that is slowly and with constant force pressed into the surface of the material. The depth of the hole is then measured and a formula is used to calculate the hardness in HRC.
The Rockwell scale is used to determine the hardness of knives, which is an important factor in knife performance. Harder steels are usually more brittle and harder to sharpen, but retain their sharpness longer. Conversely, softer steels are easier to sharpen and may be better suited for certain tasks, such as slicing food.
So when choosing a knife, it is important to take the Rockwell hardness scale into account and consider what hardness of steel is best for the task at hand.