Japanese Swords Through the Eyes of a Modern Bladesmith: Shared Techniques and Unique Challenges

"Blade Craftsmen" and "Sword Smiths"—The Distance and Intersection Between Two Worlds

Japan is home to two types of blacksmiths: the "sword smith" (tousho) who forges Japanese swords, and the "blade craftsman" (hamonoshi) who hand-crafts kitchen knives, sickles, farm tools, and similar implements. The world of sword smiths, overseen by the Cultural Properties Commission's sword smith registration system, and the world of blade craftsmen, which has developed independently as an industry, share many foundations in their techniques, yet they possess decisive differences as well.

From an outside perspective, both professions might seem to fall under the single category of "blacksmith," but the paths they have taken differ in how they choose materials, how they forge steel, and what purposes they aim to achieve when working the metal. Blade craftsmen pursue cutting sharpness and durability in tools that support daily life, while sword smiths are required to achieve not only functionality but also the completeness of works of art.

This article examines, from the perspective of craftsmen actually engaged in blade making, the technical commonalities between Japanese swords and general blades, as well as the unique challenges inherent to sword-making. It also addresses practical questions that blade craftsmen frequently encounter when considering a transition to sword smithing.

Shared Technical Foundation—Steel Selection and Forging Principles

Both blade craftsmen who make kitchen knives and sickles and sword smiths face the common challenge of "controlling carbon content in steel." The steel materials used in kitchen knives (white paper steel, blue paper steel, SKD stainless steel, etc.) are industrial products with uniformly controlled carbon content, but tamahagane used in Japanese swords is a natural material with variable carbon content, and the sword smith must judge the suitability of materials through visual inspection and the feel of their hands.

Nevertheless, the fundamental principles of forging—"heating, striking, folding, and shaping"—are common to both. Some blade craftsmen, such as those in Sakai, employ techniques close to folding forging, and the objective of homogenizing steel structure is the same. When determining the temperature range for heating, both blade craftsmen and sword smiths rely on the color of the flame and the way sparks fly from the steel—these are refined skills passed down in both fields.

The concept of quenching (martensitic transformation through rapid cooling) is also common to both. However, Japanese swords generate their hamon through a unique process called tsuchitoki (clay application), which involves coating the blade with clay before quenching. This tsuchitoki is at the heart of the aesthetics and difficulty unique to sword-making.

The "polishing" process that follows quenching also shares common ground. Neither kitchen knives nor Japanese swords are complete products after forging and quenching alone; they require finishing polishing by a polisher to reveal their true sharpness and form. In the case of swords, specialized polishing techniques are further required to accentuate the beauty of the hamon and jihada, and the division of labor between smith and polisher is also characteristic.

Aspects of Japanese Swords That Surprise Blade Craftsmen

When a blade craftsman experienced in making kitchen knives for many years observes the process of Japanese sword-making, they find several points surprising.

First: The Difficulty of Handling Tamahagane Unlike industrial steel, tamahagane has uneven distribution of carbon content and impurities. Sword smiths accumulate sensory judgments that cannot be quantified, such as "examining the cross-section by splitting the steel" or "judging by the color of the flame and the steel's reaction." While blade craftsmen also consider material assessment important, they rarely have the opportunity to work with natural materials with such variability as tamahagane. The very process of "steel selection"—differentiating between harder and softer sections of steel and deciding where in the blade to use each—is treated as an independent specialized skill.

Second: The One-Shot Challenge of Tsuchitoki and Hamon Formation Even if a kitchen knife's quenching fails, it is possible to re-heat and retry to some extent, but Japanese sword quenching with tsuchitoki is essentially a one-shot endeavor. The clay mixture, thickness, drying condition, furnace temperature, and water tank temperature—all of these must align perfectly to achieve the desired hamon. Once a mistake is made, the steel's structure becomes altered, and correction becomes extremely difficult. This tension is something that is rarely experienced in the production-oriented environment of kitchen knife smithing, according to craftsmen in that field.

Third: The High Standard of Aesthetic Demand For kitchen knives, "sharpness" is the top priority, and aesthetics are a secondary concern. Japanese swords, by contrast, are evaluated for their cutting edge equal to or more than their cutting sharpness, including the beauty of the hamon, the texture of the jihada, and the form of the kissaki. The aesthetic sensibility that says "this hamon is beautiful" must be cultivated separately as a sword smith.

Fourth: The Length of the Production Process Many kitchen knives can be completed in a relatively short process from forging the material to edge finishing, but Japanese swords typically go through multiple specialized stages—forging, extending, tsuchitoki, quenching, polishing, and the creation of sheaths and handles—with different craftspeople sharing responsibility for each stage. The sword smith's role is limited to the forging of the blade itself, and before the finished product reaches the market, it passes through the hands of polishers, sheath makers, handle wrappers, and other craftspeople.

Challenges When Blade Craftsmen Aim to Become Sword Smiths

In recent years, there has been a steady number of cases in which blade craftsmen who make kitchen knives or farm tools pursue sword smith certification. Although the Cultural Properties Commission's sword smith certification system does not have an explicit provision favoring blade craftsman experience, the existence of forging technique foundations can sometimes reduce the training period.

The obstacles to overcome are clear: the procurement and material assessment skills for tamahagane, mastery of tsuchitoki technique, and most difficult of all, the cultivation of aesthetic eye for hamon and jihada. This requires not only sword-making itself, but also extensive viewing of masterworks by predecessors and time spent absorbing the unique aesthetic sensibility of the sword world.

Common Questions When Considering Such a Transition

• Will experience in knife-making not go to waste?—The fundamental principles of forging and quenching are shared, and the sense of hammer control and fire management serve as a foundation. However, the handling unique to tamahagane and tsuchitoki must be learned anew from scratch.
• Can tools and equipment be repurposed?—While the basic concepts of equipment such as furnaces and anvils can be shared to some extent, Japanese sword forging and tsuchitoki require specialized tools, so the equipment used during the blade craftsman years cannot always be directly repurposed.
• How is aesthetic eye cultivated?—Continued exposure to viewing, such as seeing many existing masterwork swords in person, touching real pieces at museums and sword shops, is essential. This is something that cannot be supplemented by technical books alone; it is something cultivated over time.

Reverse Application—The Influence of Sword Smith Techniques on the Blade World

There are also examples of sword smith techniques influencing the general blade industry. The concept of homogenized steel achieved through folding forging is attracting attention in the Western kitchen knife world as a technique similar to Damascus steel (laminated steel). Additionally, the "single-bevel quenching" technique, which applies quenching only to the edge, is the application of sword-quenching principles to blade manufacturing.

In the Gifu-Seki blade industry, products incorporating Japanese sword folding-forging techniques into high-end kitchen knives are being produced, and the technical boundary line between swords and knives remains fluid even today. Examples can be found of craftspeople who have experience as sword smiths later transitioning to the creation of kitchen knives or artistic blades, combining techniques from both fields.

This flow of techniques is not one-directional. The dedication to cutting sharpness as a practical blade that blade craftsmen have cultivated, and the process management concepts developed with mass production in mind, are also adopted in sword-making workshops.

Conclusion—The Shared "Spirit of Facing Iron" in Blade Craftsmen and Sword Smiths

Blade craftsmen who forge kitchen knives and sword smiths who forge swords are fellow craftspeople in that they confront the nature of steel and use furnace temperature and hammer force to bring out its potential. However, Japanese swords add a dimension of "pursuit of beauty" that transcends the pursuit of practical sharpness. The hamon achieved through tsuchitoki quenching—this is what distinguishes the sword smith profession from that of a mere blade craftsman.

The technical dialogue between these two fields holds the potential to enrich Japan's entire blade-working culture, and deeper development of craft exchange and industrial collaboration is anticipated. Whether kitchen knife or sword, the very stance of craftspeople who continue to face a single piece of steel is the shared foundation that has supported Japan's forging culture.