Banshu-miki cutlery Banshu miki uchihamono
A shining blade born of repeated tempering
Japanese traditional forging passed down to the present day
What is Banshu-miki cutlery ?
Banshu Miki Uchihamono are metalwork produced around Miki City, Hyogo Prefecture. Banshu Miki Uchihamono, as well as Shinshu Uchihamono and Tosa Uchihamono, are all renowned as large craft production centers of blades in Japan using a mold forging technique .
Banshu Miki Uchihamono are distinguished by the wide variety of blades made using traditional manufacturing methods, such as knives, chisels and planes and construction tools; each item is carefully produced by one craftsmen.
The forging said to be the basis of Banshu Miki Uchihamono, is about 1500 years old. It originated when Korean blacksmiths from Kudara settled around the former Miki city as part of a skills exchange with the blacksmiths using the Yamato forging techniques working in Japan.
But the forging technique was not finally named as Banshu Miki Uchihamono until the Edo period. It is said that, the foundations of this traditional forging technique were established in the Edo period, and it was at this time that the crafts called Banshu Miki Uchihamono were born and developed into the form we know today.
According to historical documents, it was in 1763 that the production of wide-bladed ripsaws was started and signs of the industry’s development were seen in Miki. In 1760, Edo was devastated by a large fire, creating a demand for reconstruction timber, and a consequent temporary demand for axes, saws and the like. However the history and survival of Banshu Miki Uchihamono has not always been so easy; the industry has faced several difficulties over the years, such as the loss of its exclusive distributorship in 1792; and the rapid decrease in demand for traditional forging due to the introduction of western techniques around 1885. Despite such setbacks the skills of Banshu Miki Uchihamono have been continuously passed down through the efforts of generations of craftsmen.
General Production Process
- 1. Forge Welding
The iron base is heated to a high temperature of about 1,200°C and joined with carbon steel using a bonding agent including sodium borate. Too high or low a temperature results in poor bonding of metal; the correct temperature is essential and is gauged by eye; a highly skilled task.
- 2. Forging: Beating ho (Houchi)
Houchi is the process in which just the ho, or edge of the blade is forged. By much hammer beating the steel and iron base coated with sodium borate are tightly combined. The rough metal for the blade is made bigger than the final blade and is cut to size.
- 3. Forging: Beating jiku (Jikuuchi)
The remainder of the blade is now forged and careful attention paid to the temperature. This is followed by the creation of the tang or nakogo to fit into the handle.
- 4. Smith forging
The forged blade is again put into the fire to firm the shape. Mino blades are characterized by their thin edge. Too much heating makes the blade weaker. Smith forging requires strict heat control at a temperature between 950° and 1,000°C. Then the heated blade is forged again while adjusting the thickness and width.
- 5. Annealing
Annealing is carried out by placing the blade in straw ashes and heating at a low temperature of about 750℃.
Annealing is done to crystallize the sodium borate and make it easier to work with such tools as a file.
- 6. Grinding
After annealing, the sodium borate is soft enough to be sharpened with a file and the shape is adjusted by grinding. Firstly, rough sharpening is done so that the spindle part becomes round. Next, the back is roughly planed. The surface is planed smooth by buffing, or polishing while rotating with a round cloth and grinding agent.
- 7. Quenching
The buffed steel is heated again for a few minutes at a low temperature between 700º and 800℃. Then the steel is cooled down by quickly plunging into water. Furthermore, unlike the heating processes until now, quenching is distinguished by the application of polishing powder to ensure equal strengthening of the blade; quenching brings out the beauty of the blade surface.
- 8. Tempering
After hammering out the distortions of quenching, tempering an important process is carried out. By strictly following the tempering process, the blade becomes shiny; after tempering with oil, the blade is rinsed with water, salted at a temperature of 150℃ and then tempered again.
- 9. Finish polishing
The blade, which is heated and tempered repeatedly, is then ground again and in the final process, by carefully polishing the edge the blade is given a an extremely sharp edge and finished.
Where to Buy & More Information
Miki Hardware Museum
ClosedMondays (open if Monday is holiday and closed the next day), December 29 to January 3
Business Hours9am to 5pm
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