Polishing from Foundation to Finish—Detailed Explanation of 12 Steps in Japanese Sword Polishing

Polishing Reveals the Beauty of the Sword—The Essence of the Polisher's Work

The beauty of the Japanese sword—the brilliance of the blade pattern (hamon), the skin texture (mokume) of the ground steel (jigane), and the geometric sharpness of the ridge line (shinogi)—exists in a "dormant state" in the stage when the swordsmith has forged and heat-treated the blade. It is the polisher's (togishi) role to bring this beauty to its fullest, and polishing is not merely surface treatment but an artistic act of "revealing the sword's inherent beauty."

Japanese sword polishing generally divides into two major stages: "foundation polishing" (shitaji-togi) and "finishing polishing" (shiage-togi), each containing multiple steps. The whetstones used change in fineness (grit) with each stage, progressing from coarse to increasingly fine stones. While the complete process varies by school and individual polisher, twelve basic stages are generally recognized. As of 2026, the number of young polishers learning traditional polishing techniques is increasing, yet mastering the skilled techniques still requires a lengthy apprenticeship.

Foundation Polishing Steps—Rough Work to Shape the Blade

1. Coarse Stone (Ara-to)

The coarsest whetstone used first. After forging and heat-treating, the blade surface retains forge marks, oxidation film (scale) from heat-treatment, and scratches from previous polishing. The coarse stone removes these defects and establishes the blade's basic shape (curve, edge angle, and spine form). The typical whetstone grit equivalent is #100–#320.

2. Medium Stone (Naka-to)

This stage removes scratches from the coarse stone while refining the blade's detailed form. Fine adjustments to edge angle, clarification of the ridge line, and setting the point angle are performed in preparation for subsequent finishing polishing. The grit equivalent is approximately #400–#600.

3. Edge-Setting Stone (Hatori-to)

A process that establishes the polishing angle toward the edge. From this stage onward, the sensory technique of "polishing only the edge" becomes necessary, making the polisher's experience and sensitivity especially critical. The edge angle (angle of the edge line) is now determined, fixing both the blade's cutting ability and the visual position of the blade pattern.

4. Iyo Stone (Iyo-to) / Iga Stone (Iga-to)

These natural whetstones, named after their mining regions, serve as the transition between foundation and finishing polishing. Scratches on the blade surface gradually become finer, and the outline of the blade pattern begins to emerge.

Finishing Polishing Steps—Delicate Work to Reveal Blade Pattern and Ground Steel Beauty

5. Uchigunori Stone (Uchigunori-to)

A critical whetstone marking the entrance to finishing polishing. Using natural Uchigunori stone (Kyoto/Yamashiro production is considered highest quality), the entire blade is polished to fine fineness. At this stage, the "scent line" (nioi-guchi)—the clarity of the blade pattern outline—begins to appear.

6. Habaki Base Polishing

Careful polishing of the area above the habaki (metal collar at the blade's base)—the stem area near the habaki that is often overlooked in standard polishing.

7. Edge Gloss (Ha-zoya)

A technique using thin stone pieces (Uchigunori stone broken into small pieces or specialized edge-gloss stones) drawn with a finger along the edge in one direction. This is one of the most critical steps for bringing out "the whiteness and brilliance of the blade pattern"—especially the sparkle of the nie and nioi near the edge boundary.

The visual difference created here has metallurgical foundation. The edge of a Japanese sword comprises martensite structure (hardness HRC60 or higher), while the ground steel portion contains mixed pearlite and ferrite structures. These structures resist polishing differently, so identical whetstones create different removal rates, and the blade pattern boundary emerges as visual contrast. By subtly varying whetstone angle, pressure, and contact point, the polisher maximizes this structural difference to create expressive blade patterns.

8. Ground Steel Gloss (Ji-zoya)

A technique applying whetstone pieces to the ground surface (flat portion) to polish it. By applying stones at a different angle than edge gloss, the ground steel's skin texture (itame, mokume, wood grain, ayasugi patterns) becomes clearly visible. It is no exaggeration to say that the beauty of the ground steel is determined by this step.

9. Wiping (Nugui)

Rather than whetstone polishing, this step uses "wiping paper" mixed with pine resin (matsu-yani) and metal powder to polish the entire blade. Performed after ground steel gloss, it causes the entire blade to take on a dark tone, and the subsequent edge-setting makes the blade pattern stand out more brightly and vividly.

10. Edge-Setting Finish (Hatori-shiage)

The final edge-setting that tapers and sharpens the edge. This uses thin whetstone plates or specialized "edge-setting stones." By performing this step on a blade darkened by wiping, the blade pattern emerges in white, and the final cutting ability and edge beauty are confirmed.

11. Point and Hamon Shape (Kissaki and Boushi) Polishing

The point (blade tip) and hamon shape (blade pattern in the point area) are the most complex-shaped parts of the blade, requiring delicate work with specialized small whetstones. The hamon shape (sweeping, round hamon, large round hamon, flame hamon, etc.) and blade pattern clarity are finalized in this step.

12. Final Polish

A final stage confirming overall finish quality while removing all microscopic scratches created by whetstone polishing. The ideal completed polish has the blade pattern, ground steel, and ridge line all gleaming in optimal condition.

Types of Whetstones Used—From Natural Stone to Synthetic

Whetstones used in polishing divide broadly into "natural stones" and "synthetic stones." The highest quality natural Uchigunori stone (Kyoto production) is preferred for finishing polishing, and steps like edge gloss and ground steel gloss use "edge-gloss and ground-steel-gloss stone chips created by hand-rubbing individual grains onto metal plates." The supply of natural whetstone deposits is declining, making quality stone acquisition a significant challenge for polishers. In recent years, synthetic whetstone quality has also improved dramatically, and some steps now achieve finishes comparable to natural stones.

The Japanese Art Sword Preservation Society recognizes several hundred polishers nationwide, but among them, skilled artisans capable of executing the complete advanced finishing polishing process are increasingly limited. Uchigunori deposits are already severely depleted, and most working polishers manage quality stone preservation and acquisition individually. Due to this scarcity, the cost of traditional full polishing varies with blade condition and length but frequently exceeds several hundred thousand yen.

Conclusion—The 12 Stages of Polishing Perfect the Sword's Beauty

Japanese sword polishing is not merely "cleaning" work but an artistic process of "gradually revealing the beauty inherent in the blade." Finishing polishing progresses through edge gloss → ground steel gloss → wiping → edge-setting in sequence, bringing the blade pattern's brilliance and ground steel's skin texture to maximum expression. Without the polisher's skill, no matter how superior the blade in the forging stage, its true beauty cannot be revealed. Deepening understanding of Japanese sword polishing becomes the first step toward enriching the profound appreciation of sword appreciation.