What is "honyaki"

Honyaki knives are a method of forging a knife from one single material, almost always high-carbon steel, and quenched in oil (abura-honyaki) or water (mizu-honyaki) with clay to yield a soft, shock absorbing spine and hard edge for high sharpness. Note that Japanese bladesmithing is considered sacred and is often secretive, for personal, economic, and traditional reasons, and so the topic area is especially subject to misinformation, misinterpretation, and omission except for those within the craftsmans' circle. Furthermore, blacksmithing backgrounds (i.g. forestry/farm tools, kitchen knife, swordsmith) differ and product philosophy will differ accordingly. Honyaki is an intersection between the knife smith and swordsmith. Since there is no need to forge weld, which occurs at around 1000 degrees Celsius, honyaki in the first steps avoids the possible grain growth at such temperatures and, in combined with a different heat treat, generally allows for a finer grain structure and one factor to greater edge taking and holding than zen-kou, which are monosteel knives cut from sheet metal without differential hardening, or awase-bocho (kataha two-layer, sanmai three layer in U shape with hagane in middle, and warikomi three layer sandwich), which are knives made from a hard steel clad with another metal. During the forging to shape, the carbon steel of honyaki is more resistant to hammer blows than awase bocho, since the latter make use of soft, pliable iron (and in some cases stainless steel). Awase bocho before quench are covered in a uniform coat of clay for more equal heating and even color to judge the right temperature for quench. Honyaki are coated with clay only at the spine, or thick clay at the spine and thinner clay on the rest of the blade. Honyaki are usually thicker than other types of construction because thinner knives often warp or crack during the quench, and the wear resistance that allows greater edge holding makes it tedious to grind and polish. Care is taken to avoid warping and cracking after forging to shape by annealing, thermal cycling, skilled use of forge heat, and proprietary techniques. If the knife is blue steel, there is often alloy banding, giving a wood grain or Damascus look. This is more prevalent with more alloy and carbon and with a faster quench. A successful quench is better ensured by use of uniform, fine pine charcoal, expert management of the fire, exact cleaning, surface prep, and rough grinding of the blade, uniform application of the clay, proper qualities of the clay and application, controlled ambient temperature, light, and moisture, water temperature, quench technique, and eye for the right steel color. Failed inevitably blades occur, and it is a loss of time, steel, and emotion. This difficulty, combined with the sensitivity to abuse and often glassy feel in sharpening, turn many smiths to work to perfect their awase construction. Nonetheless, there are chefs and smiths who see honyaki as the ultimate combination sharpness, edge feel, and edge retention.

The grind or geometry of the end knife is often thicker than a similar awase or zen-ko knife. It feels wasteful to grind away usable material, and the wear resistance makes it tedious. However, the blade will easily and securely cut through food. The most common grind employed is the S grind, with convexity right behind the edge and concavity behind that. This concavity may extend all the way up to the spine, turn in to another convexity (like a W), or extend all the way to the edge, with the convexity being provided only by a hamaguri edge. A thicker knife is simply heavier, with a greater chance of cracking hard vegetables. The thinness provided by concavity bites into the food and the gradual sloping outwards secures the cut in steering the cut left or right. The curve and transition line release the food, and the convexity separates taller food. Done and finished well, a thicker knife inspires confidence. A common conception is that oil quenched honyaki yield a lower hardness, often around 60-63 Rockwell C, and have greater resiliency and toughness and that water quenched will be harder, often around 63-66 Rockwell C, and have a greater ability to hold a finer edge, but be much less resilient and tough, and thus easier to break. The final hardness and edge characteristics ultimately depend on both the heat treat and steel used, which is rooted in the smith's own ideals in blacksmithing and on how the knife should perform with consideration of the user's skill, appreciation of the knife, and experience with food. Blue steel is deep hardening and does not need to cool quickly to harden. If it is cooled too quickly, it will crack. This means developing a hamon with such steel requires experience and an exacting temperature control. White steel is shallow hardening and is more easy to develop a clear hamon. The hamon demarks the hard and soft steel and the transition. It is a major and celebrated aspect of Nihonto, Japanese blades, and a major reason for emotions over honyaki.

Traditionally, chefs first use honyaki at the end of their apprenticeship, signified by a silver colored metal band in the handle between the buffalo horn bolster and wood. Handles are often ebony for its gloss, weight, and stain resistance instead of traditional ho wood, Japanese magnolia. Feedback during cutting is superb and allows the chef to feel the different textures and density of food, and the surface finish of the food allows for a fresher, more intense flavor. The most common honyaki are shobu-hocho, or sashimi knives, the most common of which is the yanagiba. Honyaki are traditionally finished on Japanese natural stones from the east side of Mt. Atago in Kyoto. The most common honyaki steels are made by Yasuki of Hitachi Metals: White 2 and Blue 2.

Some honyaki makers accessible outside of Japan include Masamoto Tsukiji and Sohenten, Monzaburo, Shiraki (a smith who makes them for Tesshu, Shiro, Hide brands), Genkai (a smith who makes them under his brand Fudo Kuniyuki, and some others like Yoshihiro), Mizuno Tanrenjo, Watanabe, Konosuke, Sukenari, Kikuichimonji, Ittotsai, Singatirin, Nenohi, Yasha Yukawa, Kiyoshi Kato, and Tagaki.

Some Western makers make knives like Japanese honyaki and include Chris Anderson.