Differential Hardening Sunnobi Tanto

Sunnobi tanto are larger than ordinary tanto (nagasa above 1 shaku) and may have sori similar to ko-wakizashi. Read more about the process of yaki-ire.

1. Using approximately a 1:1:1 mixture of natural clay, polishing stone powder and ground charcoal to mask the back of a hand forged blade about 1-1.5mm thick to slow down the cooling rate.
2. Brushing on a thin slip layer with extra charcoal added along the exposed edge to speed up the cooling rate and protect from carbon loss.
3. Carefully heating in a charcoal forge supplied by air from a fuigo box bellows until the edge reaches critical temperature.
4. Plunging edge-first into cold rainwater to cool the blade quickly and harden the edge while leaving the rest tough and resilient.
5. Testing for successful hardening with a file and then removing the clay with a mild steel scraper.
6. Slightly reheating the blade over the flames to temper the edge.
7. Test polishing on a coarse Japanese waterstone to check the hamon.

Yakiire – Traditional Clay & Water Quench

The immersive experience of being in the darkened workshop during a traditional clay and water quench using a charcoal forge. A hamon is created on a tanto using a 1mm thick layer of roughly 1:1:1 natural clay, charcoal powder, and polishing stone powder. The blade is about 29cm long (nagasa), 2.3cm wide (motohaba) and 6mm thick (motokasane). The final shot shows the rough kajitogi polish to check the hamon placement using a very coarse waterstone (torajirushi 80#, lobstercarbon 120#).

Futokorogatana Kaiken Tanto

Futokorogatana (懐刀) is translated as “clothing fold sword” and describes a type of tanto mounting meant to be carried in the kimono sleeve or fold. Also known as kaiken, this humble style of hidden mounting is usually unadorned with a smooth profile and lacquer finish. More photos and information.