Building Simple Charcoal Forges

Building two examples of quick and simple sideblast charcoal forges with found and reclaimed materials to demonstrate that lack of equipment and materials should not be a major obstacle.

Ways to improve and expand on these concepts include: mixing copious amounts of chopped straw or charcoal powder (6:2) into the clay to make it refractory, using high temperature kiln bricks, making the walls higher and longer, using the clay to narrow the tuyere to about 1sun/3cm right where it enters at the bottom side of the forge, putting a barrier up to protect the fuigo (and allowing a shorter pipe), allowing the clay to dry before lighting the forge, etc.

Learn more about fuigo, a full traditional swordsmith forge build, or a smaller tanto forge design.

Making a Bamboo Scoop for Water Forging

Simple technology for pouring water on the anvil, takeno mizusashi (竹の水差し) made from a piece of bamboo.

Forging with a thin film of water on the anvil and hammer prevents forge scale or oxide from being hammered into the surface of the steel. The hot steel instantly vaporizes the water and the resulting steam explosion blows the scale off of the work, keeping it clean as it is worked. This type of bamboo scoop is a traditional style tool for evenly applying water to the surface of the anvil or the hot steel. Read more about the process of making one.

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.