

Early in the 20th century, two inventors named Rockwell patented a device that tested metal's hardness. The Rockwell hardness test applies to a range of metals from copper to iron, with a scale that expresses hardness. Find out how Seido uses metals high on the Rockwell C scale (HRC) to produce the finest knives for home and commercial use.
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The Rockwell hardness scale is a standard of measurement for metals, including knife blades. It actually consists of three scales: A, B and C. Rockwell A (HRA) applies to soft materials; Rockwell B (HRB) is used for soft metals, like copper alloys, aluminum and this steel; Rockwell C (HRC) is used for harder steel, like that used in our knives.
The Rockwell metal hardness test device has a diamond-tipped indenting tool that applies pressure to metal to gauge the material's resistance. The indentation's depth reveals the metal's hardness, with a deeper mark indicating a softer material. Each scale uses a different type of tester device.
Because slight variations can occur during hardening, a product can have a range of HRC scores, which should show no more than a 2-point span. For example, our Executive Japanese Damascus Steel Knife Set has an HRC rating of 60 to 62.
Harder and softer steel both come from the same alloy material. The hardness is the result of tempering, a heat treatment that increases the HRC of the metal.
Remember, though, that the hardest steel does not necessarily make the best knives for your kitchen. Hard steel retains a sharp cutting edge longer, requiring less frequent sharpening. However, the higher the knife’s HRC number, the more brittle it becomes.
Ultra-hard metal cracks, chips and shatters more readily than softer steel, which bends rather than breaks. Bent cutting blades need sharpening more often. So, although you will spend more time maintaining your knives with whetstones, they will resist breakage.
Our premium Japanese knives have Rockwell ratings in the 56 and 62, depending on their intended use. With proper upkeep, they will serve you well over the long term. Our FAQ Damascus Steel Knives section provides further details.
High Rockwell hardness scale knives can hold a very sharp edge longer than softer steel, which is critical to fast and effective food preparation. However, you should not use premium knives for anything other than their intended use, or you risk damage. These meticulously crafted culinary tools are designed for specific food preparation tasks. For instance, you should not use a chef’s knife to cut through heavy bones like ribs. For that purpose, a premium cleaver works best.
High-ranking Rockwood hardness scale knives may be more brittle than those made of softer steel, but in many cases, manufacturers of premium knives incorporate features that bolster their durability. For example, our executive series knives have a rugged V-10 super steel core and 67 layers of high-carbon Damascus steel for prolonged durability.
Premium tools like high-density steel knives make your culinary efforts easier and more successful. The quality materials and construction that go into a robust knife give you confidence throughout your kitchen experience. Ergonomically engineered knives that are carefully balanced from point to handle butt make chopping, slicing and cutting virtually effortless, cutting down on cooking fatigue.
Maintenance for your premium knives helps ensure they perform better and last longer. Japanese knife care is not time-consuming or difficult. Some key practices include:
High HRC hardness is a critical feature of the best chef’s knives. If you want to upgrade your kitchen skills, a sharp, durable knife set is a great place to start. Look for steel that is well-tempered with a high HRC score. Also, consider the durability of the blade construction and ergonomic design of the knives you select for top-quality results.
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