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

Sword Body Engravers (Horimono-shi) and Their Work — Engraving Spirit into Sharpened Blades

Sword body engraving (horimono) is a specialized technique that uses bladed tools such as chisels (nomi), engraving chisels, and small knives to carve patterns, characters, and designs into the surface of a blade after it has been polished. The types of patterns engraved on the blade are diverse, including dragons, swords, Sanskrit characters (bonji), coiled serpents (kurikara), ritual sticks (gomabashi), grooves (bouhi), and subsidiary grooves (soehi), each carrying religious, magical, and aesthetic significance.

The sword body engraver (horimono-shi) is neither a sword smith nor a polisher (togishi), but rather an independent craftsperson who specializes in one of the final stages of sword production. Becoming a master engraver requires a minimum of 10 years of training, and there are extremely few full-time professional engravers currently active in Japan. They are counted among the rarest specialist craftspeople in the sword-related trades.

The location where engraving is applied also varies. Depending on the client's beliefs, preferences, and the style of the period, patterns may be placed on the ridge-side surface (shinogi-ji), the flat surface (hiraji), or near the tang (nakago). Designs such as dragons and coiled serpents often carry meanings related to warding off evil and prayers for victory, while Sanskrit characters are said to embody Buddhist protective significance. The selection and placement of these designs is itself an important skill required of the engraver.

Tools Used by Engravers — Types and Selection of Chisels and Engraving Knives

In sword body engraving, the tools used are often made and adjusted by the engravers themselves. It is rare to use commercially available engraving tools as-is, as specialized tools adapted to the hardness and curved surface of the blade are necessary.

The chisel (nomi) is the primary tool in sword body engraving. Multiple sizes are used, from extremely fine ones with a blade width of less than 1 millimeter to those around 5 millimeters wide. They are classified according to the cross-sectional shape of the blade as follows.

• Flat chisel (hiranomi)
• Round chisel (marunomi)
• Triangular chisel (sankakunomi)
• V-shaped chisel

Different types must be selected depending on the subject being engraved.

• When engraving dragon scales (uroko): round chisel
• When engraving straight grooves (hi): flat chisel
• For fine details of Sanskrit characters: triangular chisel

Engraving knives are smaller than chisels and are used for detailed work. When engraving fine patterns along the curved surface of the blade, longer blades become difficult to control, so shorter and more manageable engraving knives are used. Particularly when engraving Sanskrit characters (characters from the Sanskrit script), precise engraving knives are essential for accurately rendering the curves of the letters.

Small knives (kogatana) are used for finishing and corrections. They are used to correct over-carved areas and to clean up outlines, but since they must work with the hard material of the blade, they need to be made of steel with higher hardness than ordinary wood-carving small knives.

Before engraving begins, ink lines are drawn on the blade to serve as a guide. The engraver first uses a brush or ruling tools to outline the design, then advances the chisel along those lines. The blade is fixed with a specialized holder or vise-like fixture so it does not move during work, and the engraver uses both hands to strike the chisel while keeping the blade stable. As bladed tools lose their sharpness through use, it is standard practice to sharpen them repeatedly during breaks in the work.

The Role of Whetstones — Maintaining Tools and Preparing the Blade Surface

In sword body engraving, whetstones serve a dual role. One is to keep the chisels and engraving knives used in a constantly sharp state. The other is to finish the blade surface after engraving.

The whetstones used by engravers are often of a different type than the finishing stones used by polishers (togishi). For sharpening tools, medium and finishing stones are used in combination to maintain appropriate blade angles (hakado) on the chisel. For finishing the engraved areas of the blade, engravers work in collaboration with polishers, carefully polishing only the engraved portions using extremely fine whetstones.

Pre-engraving surface preparation of the blade is also important. The blade surface finished by the polisher is already extremely smooth, but in areas where engraving is to be applied, the surface may be intentionally roughened slightly to prevent tool slipping. This treatment is calculated to disappear during subsequent re-polishing.

During engraving, a small amount of oil may be used on the blade edge and surface to suppress frictional heat and metal dust scattering. Since fine metal shavings (fragments) adhere to the engraved surface, constantly wiping them away while checking the progress of the pattern is an essential part of the work.

The Blade as Material — How Hardness and Material Quality Constrain Engraving Technique

The tamahagane (high-carbon steel) used in blade bodies becomes extremely hard on the surface after hardening. This hardness imposes significant constraints on the engraver's work.

Compared to carving wood or stone, engraving onto a hardened blade is vastly more difficult. When carving into hard material, tools tend to slip easily, and excessive force risks breaking the tool or damaging the blade. For this reason, engravers must develop the proper touch through years of experience.

Additionally, grooves called hi are often cut into the blade. There are multiple forms such as bouhi, soehi, and nifushi hi, which are carved out using a specialized tool called a groove chisel (hi-nomi) rather than by engraving. The uniformity of the angle, depth, and width of the groove has a major impact on the beauty of the sword, requiring advanced skill and intense concentration.

Working with such a hard blade material causes tools to wear quickly, and chisel edge damage and breakage are not uncommon. For this reason, engravers prepare extra tools in advance and frequently inspect the condition of the blade during work. Since the process also involves maintaining the same posture for extended periods, it is work that requires not only concentration but also the physical endurance to withstand prolonged strain.

The Working Environment of Modern Engravers — Lack of Successors and the Challenge of Passing Down Technique

The number of sword body engravers in modern Japan is estimated to be fewer than several dozen nationwide. This is a particularly small group even among sword-related craftspeople, and the shortage of successors has become a serious issue.

The working environment varies from craftsperson to craftsperson, but many engravers use one room of their home as a workshop. Sword body engraving is difficult to mechanize, and all processes are performed by hand. Good lighting, a stable work table, and accurate eyesight (or a magnifying glass) are essential.

In terms of technique transmission, direct instruction from master to apprentice is the only method. The techniques of sword body engraving are difficult to convey through text or video; they can only be mastered through years of observing the master's hands and repeated trial and error. While this rigidity of the apprenticeship system can be an obstacle to cultivating successors, it is also an indispensable framework for maintaining the quality of the technique.

It is difficult to make a living solely from engraving work, and many craftspeople combine it with other sword-related work such as polishing or tsuba-guard crafting. Among the swords in circulation on the market, some bear engraving by renowned engravers, and understanding the quality and meaning of the engraving is one of the important aspects to appreciate when viewing or purchasing swords.