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#). learn more about yaki-ire

Process: Making the Fittings – Aikuchi Tanto Koshirae

The fuchi and koiguchi are from a reclaimed buffalo horn souvenir, the kurikata is from a reclaimed horn button, the wrapping is rawhide samegawa, the mekugi is copper and silver. All of the parts are first shaped and fit, then the samegawa is wet formed to the handle contours, dried, and then attached with sokui (rice paste glue). After the scabbard and handle are lacquered, the horn parts will be polished and attached with sokui as well. The mekugi cap is soldered on with hard silver solder in the charcoal forge. carving the inside | carving the outside | final work