Sharpness and cutting performance

About Sharpness and Cutting Performance

When discussing cutting performance, one common challenge in the knife industry is how to accurately measure it. A widely recognized method is the CATRA (Cutlery and Allied Trades Research Association) tester. However, due to the high cost of the CATRA tester, it is primarily used by larger knife manufacturers.

https://www.catra.org/testing-equipment/knives-blades-cutting-edges/sharpness-and-life-tester/

The CATRA tester measures sharpness by cutting through standardized synthetic paper, which is loaded with 5% silica to simulate abrasive conditions. It generates two important metrics:

ICP (initial cutting performance)

Number of synthetic paper sheets cut in the first three cycles
Represents the blade's sharpness when first supplied or after sharpening, giving a snapshot of its initial cutting ability

TCC (total card cut - sometimes also referred to as CER = cutting edge retention)

Number of sheets cut over 60 cycles
Represents the blade's ability to retain sharpness over time, providing insight into its edge durability and overall longevity

While the CATRA tester provides useful insights into a knife's cutting performance, it does have limitations:

It simulates slicing cuts, which tends to favor coarse or serrated edges (serrated knives often produce the highest TCC values!).
Blade geometry and surface finish—aside from the edge angle—have no influence on the test results.
The values don’t accurately reflect a knife’s push-cutting ability.
The test doesn’t measure the cutting feel or how smoothly the blade glides through food

For a more precise measure of sheer sharpness at the cutting edge, the BESS (Brubacher Edge Sharpness Scale) sharpness tester is often used.

https://www.edgeonup.com/index.html

This device measures the force, in grams, required to cut through a standardized and certified wire. The lower the value, the sharper the edge. This device is relatively inexpensive, making it accessible to smaller knife makers, knife enthusiasts, and even home sharpeners looking to test their sharpening skills.

However, the BESS value only reflects the sharpness of a new or freshly sharpened blade. It doesn’t provide any information about the blade’s ability to hold an edge over time.

Aside from the CATRA and BESS testers, there are currently no widely accepted testing standards or devices that can measure a knife’s overall cutting performance and convert it into objective values. This means that while these tests provide insights into specific aspects of performance, there’s no single method to fully evaluate a knife's cutting ability across all uses.