Cutlery

Bringing the traditions of the past to the present: Skilled cutting techniques foster Japanese culinary culture

It is said that a foundation from which forging technologies could develop was already in place in Sakai due to the manufacturing during the fifth century of tools for building the city's many tumulus burial mounds. The subsequent cultivation of tobacco brought from Portugal in Japan in the second half of the sixteenth century spurred heavy demand for knives capable of cutting tobacco leaves, and Sakai became the first area to produce the new "tobacco knifes." The unique sharpness of these knives caused the government during the Edo period to designate the Sakaikiwame brand, creating a new government monopoly whose reputation for quality would gain recognition throughout the nation.
The traditional techniques used to manufacture Sakai cutlery evidence a division of labor among multiple workshops, including smith forging (hizukuri), where the metal is softened by heating and hammered out into the shape of the blade; sharpening and honing (hazuke or togi), where the metal is sharpened to give it an edge; and hafting (ezuke), where a haft, or handle, made of rot-resistant magnolia wood is attached to the blade.

Manufactured using forging technologies passed down from the craftsmen of long ago, Sakai cutlery consists of a two-layer structure of soft ferrite and hard steel. After being heated with coke (coal) burning at a temperature of 2,000°C, the ferrite and steel are layered on top of one another and hammered together. The most difficult aspect of the smith forging process is the maintenance of the hearth at the optimum temperature. If the coke is too hot, the blade will chip easily; too cool, and the ferrite and steel will fail to bond properly. Craftsmen must observe the heating of the red steel and adjust the hearth temperature accordingly, and the ability to discern the optimum temperature is the mark of a true blacksmith.
The skill of the craftsmen is similarly evident during the sharpening process. Asymmetry is unacceptable when it comes to knives, and the correction of asymmetries created during the forging process with a collection of large and small hammers is an important step in giving the blade an edge.
The ability to eliminate these asymmetries during repeated and rigorous checking of the blade in progress is the mark of a truly experienced craftsman.
During the final hafting step, the blade is inserted into a notch in the haft and fixed in place by striking the knife with a wooden mallet. Since excessive hammering can cause the haft to split, craftsmen listen carefully for slight variations in the sound of the blade during each stroke to ascertain how far the blade has left to go. After being stamped with the name of the individual who ordered it and the brand of the manufacturer, the knife is shipped to the customer.
Crafted with great care one blade at a time, Sakai cutlery is popular and widely respected among professional chefs, whose skill is said to be reflected by their choice of knife. Crafted to a length and thickness specified by the customer on the order of several millimeters, these blades are the combination of each craftsman's old-world skill discerning sense of intuition. Sakai's exquisitely manufactured knives continue to make a significant contribution to the development of Japan's culinary culture.

(1) Smith forging…Steel treated with powder containing boric acid and other compounds is layered on top of ferrite heated in a hearth with coke (coal) burning at a temperature of 2,000°C. The blade is then heated until it reaches about 900°C and hammered to bond the metals together.

(2) Shaping…The blade is again heated to 600° to 800°C and beat into the desired shape.

(3) Annealing…After being heated to about 740°C to eliminate internal asymmetries, the blade is allowed to cool naturally.

(4) Rough hammering…Unevenness caused by hammering during the smith forging process is smoothed and leveled. Additional hammering at room temperature serves to remove iron rust that has formed due to oxidation.

(5) Trimming …Excess metal on the annealed knife is removed to create the desired shape.

(6) Grinding and filing …Areas on the knife's edge that were bent back during trimming are removed with a grinder along with other unnecessary areas, and the blade is further shaped with filing.

(7) Clay layering …Layers of moist clay are applied to the knife to ensure that it cools quickly and evenly during the hardening process, and the knife is dried thoroughly in the heat remaining at the rear of the hearth.

(8) Hardening and tempering …In order to further harden the steel, the knife is heated to 750° to 800°C and then quenched in water. To further enhance the tenacity and strength of the steel, the knife is then heated to 180° to 200°C and allowed to cool naturally. Depending on the type of steel being used, oil may be employed in tempering process.

(9) Sharpening (honing) …The craftsman corrects asymmetries and sharpens the blade until it has a good edge. During rough, intermediate, and fine sharpening phases, progressively finer whetstones are employed to smooth the surface of the blade. Next, the knife is etched with a series of fine lines known as metoshi that serve to prevent rust, one of the characteristics of Sakai cutlery. A final sharpening step perfects the blade's edge.

(10)Hafting …A haft made of rot-resistant magnolia wood is attached with a wooden mallet and stamped with the brand of the manufacturer.