Honyaki (literally true-fired) is the name for Japanese traditional method often seen in kitchen knives of forging a blade in technique most similar to nihonto from one single piece of high-carbon steel covered with clay to yield upon quench a soft, resilient spine, a hamon (or temper line), and hard, sharp edge. Honyaki refers to either mizu honyaki (water-quench) or abura honyaki (oil quench). The term is also used to describe high-end full stainless blades and carbon blades by non-Japanese bladesmiths made similar to the traditional manner.
Contents
Process
Pine charcoal is first cut to size for use in the fire as gentle heat for the blade before quench. Coke, currently, is used as fuel to forge the blade to shape and is preheated to remove remaining sulfur and phosphorus. An electric fan is used or a more traditional box bellow to feed air into the forge. The steel is usually one of the carbon knife steels Hitachi produces at Yasugi Specialty Steel. These are the unalloyed White steel (1, 2, 3) and the tungsten chromium alloyed Blue steel (1, 2, 3) and the number 2 versions of each are most commonly used.
The 1 versions (higher carbon) are harder, more wear resistant, more fragile, harder to sharpen, and harder to make. The 3 versions (lower carbon, at the eutectoid point) are not necessarily softer, but often tougher, easier to sharpen, and easier to make. Blue steel is difficult to water quench because of its alloy content can cause cracks and is more effort to grind. White steel is difficult to quench because it requires a more strict quench temperature and keen eyes and experience in hardening.
Honyaki has no need for forge welding unless it is made from tamahagane. This skips the possible carbon migration to the mild steel, the heating to around 1000 degrees Celsius to bond the layers, and the need to evenly forge the core steel. There are multiple reheatings and forging from high temperatures downward. Blades are cooled and annealed, cut to shape, cold forged, and corrected for distortion multiple times. They are preferably left to rest for a bit between each step to help correct distortion. The knife is rough ground to shape. These steps generally require more effort than with laminated knives.
A paste is prepared from water, charcoal, clay, ground natural sharpening stone, and other ingredients in a proprietary way and composition and applied to the blade. This thicker paste goes on the blade spine on both sides and traditionally mimics the wavy hamon of nihonto. A thinner slip goes on the hard edge to help heat transfer there. The quench water or oil is prepared and brought to the right temperature.
Lights are turned off and the room shut from the outside. The blade is buried and shuffled around in the charcoal and when it reaches the correct temperature it is thrust into water and moved forward and back (so as to prevent lateral distortion) and then after a couple seconds side to side. The knife could also be brought up slightly above temperature and then held in the room to the correct temperature before quench. The quench could be interrupted for more rough grinding or to correct distortion. The blade is tempered either immediately over fire, in oil, or in an oven. The water quench often destroys many blades by cracking them or warping them too badly to reasonably fix. The labor used toward ultimately unusable products and skill in temperature control and forging leads to a much higher price than most laminated blades.
It is preferably left to sit to stabilize. If is made under the Sakai, Osaka style production system, the knife is sent to a sharpener who corrects for distortion further and makes the final geometry and profile of the knife. If it is single bevel, the urasuki and omote are made and trued. It may be mirror polished or finished with natural stones to highlight the hamon. The handle is installed and a saya is usually made.
Culture and Use
Honyaki is an intersection between the knife smith and swordsmith. Blacksmithing backgrounds (occupational, geographical, family lineage, teacher, tradition, business structure) differ and accordingly produce different interpretation of the technique. In Sakai, the blades are often sent to retail companies for final finishing and branding and the blacksmith and sharpeners are often unnamed so as to reduce competition and disrespect, as the blades come from the same pool of craftsman.
Traditionally chefs first learn to use stainless, then kasumi, hon-kasumi, abura honyaki, and finally mizu honyaki. The honyaki knives are usually used only after completion of an apprenticeship after becoming proficient in ingredients, cooking, sharpening, and knife use. Honyaki knives are usually harder to sharpen in comparison to laminated blades because they have no mild steel that is quickly removed and are usually even harder. They usually chip more easily in use and sharpening. The user must know how to hold the specific knife in honyaki method, cut, sharpen, store, and care for it. From a strictly heat treat and microscopy point of view, there should be no difference between a laminated and honyaki steel with the same observed structure and heat threat process, but many users say there is benefit to honyaki. Many users also prefer laminated blades for ease of maintenance, cost, and toughness. Many blacksmiths prefer laminated blades because they are easier to make a living on. At the highest levels they have core steel as hard or harder than honyaki and are not necessarily easier to make.
Makers
Honyaki makers (some direct blacksmiths, most resale companies) accessible outside of Japan include Masamoto Tsukiji, Masamoto Sohonten, Akifusa, Monzaburo, Shiraki (a smith who makes them for Tesshu, Shiro, Hide, Minamoto Izumimasa brands), Genkai (a smith who makes them under his brand Fudo Kuniyuki, and some others like Yoshihiro), Ino/Ittetsu, Mizuno Tanrenjo, Watanabe, Konosuke, Sukenari, Kikuichimonji, Ittotsai, Singatirin, Nenohi, Yasha Yukawa, Kiyoshi Kato, Yoshikazu Ikeda, Tatsuo Ikeda, Kenji Togashi, and Tagaki. As Sakai is the kitchen knife capital of Japan, many honyaki come from there.
Stainless "honyaki" include Suisin Inox Honyaki and Masahiro MV Honyaki.
Makers of Western style "honyaki" include Cris Anderson, Mert Tansu, Bill Burke, Bryan Raquin, William Catchside, and Bob Kramer.