What makes 1090 carbon steel a good choice for a katana?
Updated Mar 2026
1090 carbon steel contains approximately 0.90% carbon, placing it in a range that balances hardness and toughness well. During the heat treatment process, this steel responds favorably to differential quenching, which allows smiths to create a visible hamon - the wavy temper line along the edge that is both an aesthetic feature and a sign of traditional craftsmanship. Compared to lower-carbon steels, 1090 holds its edge geometry reliably over time, making it a preferred choice for collectors who appreciate pieces that reflect genuine forging discipline rather than cosmetic production shortcuts.