Category Archives: D.I.Y. Technology

Repair broken Natural Waterstone with Urushi

Repairing a broken natural Japanese waterstone using urushi lacquer. Natural urushi lacquer is strong enough to repair the stone but will not interfere with sharpening and polishing as some glues may. Carving a cypress base to hold the stone together as well as using urushi lacquer to reattach the halves provides a double solution. The stone is a Kumamoto binsui-do, approximately #700, from Monotaro in Japan. Urushi is from Watanabe~san.

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.

Making Fire with Bamboo – museum forge first lighting

The first night turned out to be quite an event as there were three forges and six blacksmiths/strikers operating in the museum workshop. Thanks to Tim of Reforged Ironworks, and Josh for their energy and charcoal chopping to get the forge up and running, and their assistance swinging the big sledges to finish drifting and shaping the smaller hand hammers as the first preparatory projects in the charcoal forge. Read more about the museum forge project or watch a more detailed demonstration of lighting fire with bamboo.

Making 篩 for charcoal screening

Traditional Japanese swordsmithing forges are fueled by softwood charcoal which is first chopped, screened, and sorted into several sizes for different stages of the forging process. The “furui” (篩) or sieve is used to separate different sizes of charcoal during the sumi-kiri process. This one is the smallest mesh of the four, made from window screen, and saves the fines for the charcoal bed and allows the powder to fall through. See the whole museum forge project here.