Tools and Materials of Blade Carving: Chisels, Knives, and Whetstones Used by Modern Horimono Specialists

Sword Carvers (horimono-shi) — Engraving Life into Polished Blades

Sword carving (horimono) is a specialized technique that uses bladed tools such as chisels, engraving knives, and small blades to engrave patterns, characters, and designs onto the surface of a blade after polishing is complete. The variety of patterns engraved on sword blades is extensive—including ryu (dragons), ken (swords), bonji (Sanskrit characters), kurikara (coiled dragon), gomabashi (ritual spatula designs), bouhii (straight grooves), and soehii (supplementary grooves)—each carrying religious, spiritual, and aesthetic significance.

The sword carver (horimono-shi) is neither a swordsmith (katanakaji) nor a polisher (togishi), but rather an independent specialist dedicated to one of the final stages of sword production. Becoming a master carver requires a minimum of 10 years of apprenticeship, and today, the number of full-time professional horimono-shi in Japan is extremely limited. They are among the rarest craftspeople in the sword-related trades.

Tools Used by Sword Carvers — Types and Selection of Chisels and Engraving Knives

The tools used in sword carving are often manufactured and adjusted by the carvers themselves. It is rare to use commercially available engraving tools as-is, since specialized tools adapted to the blade's hardness and curved surface are necessary.

Chisels (nomi) are the primary tools for sword carving. Carvers use multiple sizes, ranging from extremely fine blades under 1 millimeter to approximately 5 millimeters wide. Chisels are classified by blade cross-section shape: flat chisels (hira-nomi), round chisels (maru-nomi), triangular chisels (sankaku-nomi), and V-shaped chisels. Different tools are employed depending on the task—round chisels for engraving dragon scales (uroko), flat chisels for carving straight grooves (hi), and triangular chisels for fine details in bonji.

Engraving knives are smaller than chisels and are used for precision work. When engraving fine patterns along the blade's curve, longer blades are difficult to control, so shorter, more manageable engraving knives are preferred. Particularly when carving bonji (Sanskrit characters), precise engraving knives are essential to accurately express the curves of the characters.

Small blades (kogata-na) are used for finishing and corrections. They are employed to fix over-carved areas and to clean up contour lines. Since they work with the hard material of the blade, they require higher steel quality than ordinary woodcarving blades.

The Role of Whetstones — Tool Maintenance and Blade Surface Preparation

Whetstones serve a dual role in sword carving. One is to maintain the chisels and engraving knives in a constantly sharp condition. The other is to refine the blade surface after carving.

The whetstones used by carvers often differ from the finishing stones used by sword polishers. For tool sharpening, medium and finishing stones are used together to maintain the proper blade edge angle (hakado) of the chisels. For finishing the carved surface of the blade, carvers work in coordination with the polisher, carefully polishing only the carved areas with extremely fine whetstones.

Pre-carving surface preparation of the blade is also important. Blades finished by the polisher already have an extremely smooth surface, but areas to be carved are sometimes intentionally roughened slightly to prevent tool slippage. This treatment is calculated to disappear during later re-polishing.

Blade as Material — Constraints Imposed by Hardness and Composition on Carving Technique

Tamahagane (steel used in traditional sword-making) becomes extremely hard on the surface after heat treatment. This hardness imposes significant constraints on the carver's work.

Compared to carving wood or stone, engraving heat-treated blades is substantially more difficult. Carving hard materials causes tools to slip easily, and excessive force risks tool breakage or damage to the blade. Therefore, carvers must develop an intuitive sense of appropriate pressure through years of experience.

Additionally, blades frequently feature grooves called hi. Multiple forms exist—bouhii, soehii, nifusujii—and these are not carved but rather carved out using a specialized tool called a hi-nomi (groove chisel). The uniformity of the groove angle, depth, and width significantly influences the blade's beauty, requiring advanced technique and concentration.

Modern Sword Carvers' Working Environment — Successor Shortage and Technical Transmission Challenges

The estimated number of blade carvers in contemporary Japan is fewer than several dozen nationwide. Among sword-related craftspeople, this is a particularly rare occupation, and successor shortage has become a serious issue.

The working environment varies from carver to carver, but many work in a room within their home. Sword carving resists mechanization—all processes are performed by hand. Good lighting, a stable work surface, and accurate vision (or magnifying glass) are essential.

Regarding technical transmission, direct instruction from master to apprentice is the only method. Blade carving techniques are difficult to convey through written words or video; they must be mastered through years of observation of the master's hands and repeated practice. While this apprenticeship system's rigidity poses a barrier to nurturing successors, it remains an indispensable framework for maintaining the quality of the craft.