Polishing from Foundation to Finish—Detailed Explanation of 12 Steps in Japanese Sword Polishing
* Image is for illustrative purposes only.Table of Contents
Polishing Brings Out the Beauty of the Blade—The Essence of the Polisher's Work
The beauty of a Japanese sword—the brilliance of the hamon, the grain of the jihada, the geometric sharpness of the shinogi—exists in a "dormant state" at the stage when the swordsmith completes the forging and tempering of the blade. It is the polisher's (togishi) job to bring this to its fullest expression, and polishing is not merely surface finishing but an artistic act of "revealing the blade's inherent beauty."
The polishing of a Japanese sword generally divides into two major stages: "rough polishing (shitajitogi)" and "finish polishing (shiagegi)," each containing multiple processes. The whetstones used change in fineness (grit) with each stage, progressing gradually from coarser to finer stones. While the overall process varies by school and polisher, the following 12 stages are generally considered foundational. As of 2026, the number of young polishers learning traditional polishing techniques is on an upward trend, though mastering the skilled techniques still requires a lengthy training period.
| Stage | Process Name | Main Content |
|---|---|---|
| 1 | Aratt (荒砥) | Remove forging irregularities, oxidation scale after tempering, and scratches from previous polishing; establish the basic blade shape (curve, edge angle, spine form). Grit equivalent to approximately #100–#320 |
| 2 | Nakaet (中砥) | Fine-tune the edge angle, clarify the shinogi, set the edge-tip angle, and refine details. Grit equivalent to approximately #400–#600 |
| 3 | Hatori (刃取砥) | Set the polishing angle toward the edge and determine the edge line angle |
| 4 | Iyo (伊予砥) / Iga (伊賀砥) | Use natural whetstones to progressively refine scratches and gradually reveal the hamon contours |
| 5 | Uchigumo (内曇砥) | Polish the entire blade with natural-source uchigumo (Kyoto/Yamashiro origin is considered highest quality), at which point the hamon's nieiguchi begins to appear |
| 6 | Habaki-moto Polishing | Carefully polish the area near the nakago (tang) above the habaki, an often-overlooked region |
| 7 | Hadsuya (刃艶) | Run thin whetstone fragments along the edge boundary to draw out the maximum whiteness and brilliance of the hamon |
| 8 | Jidsuya (地艶) | Apply whetstone fragments to the flat area to bring out the jihada grain patterns (itame, mokume, mokume, ayasugi) |
| 9 | Nuguii (拭い) | Polish the entire blade with "wiping paper" (containing pine resin, metal powder, etc.) to impart a blackish tone and make the hamon stand out |
| 10 | Hatori Shiage (刃取り仕上げ) | Final edge refinement to make the edge thin and sharp, causing the hamon to appear white and distinct |
| 11 | Kissaki and Boushi Polishing (切先・帽子) | Use specialized small whetstones to finalize the kissaki and boushi shape and hamon |
| 12 | Final Polishing | Remove all microscopic scratches from whetstone polishing and confirm the final finish |
Rough Polishing Stages—The Heavy Work of Establishing Blade Shape
1. Aratt (荒砥)
The coarsest whetstone used at the start. After forging and tempering, the blade surface retains forging irregularities, oxidation scale, and scratches from previous polishing. The aratt removes these and establishes the basic blade shape (curve, edge angle, spine form). The typical whetstone grit is equivalent to approximately #100–#320.
2. Nakaet (中砥)
A stage where rough scratches are removed while refining the blade's detailed shape. The edge angle is fine-tuned, the shinogi is clarified, and the edge-tip angle is set—final adjustments to the shape for subsequent finish polishing. Grit is equivalent to approximately #400–#600.
3. Hatori (刃取砥)
The process of setting the polishing angle toward the edge. From this stage onward, the technique of "polishing only the edge" requires sensory skill, making the polisher's experience and intuition particularly important. Once the edge angle (edge line angle) is determined, the blade's cutting performance and the visual position of the hamon are fixed.
4. Iyo (伊予砥) / Iga (伊賀砥)
These natural whetstones, named after their origin regions, serve as a transition stage from rough polishing to finish polishing. The blade surface scratches are progressively refined, and the hamon contours gradually become visible.
Finish Polishing Stages—Delicate Work to Reveal the Beauty of Hamon and Jihada
5. Uchigumo (内曇砥)
An important whetstone marking the beginning of finish polishing. Natural-source uchigumo (Kyoto/Yamashiro origin is considered highest quality) is used to finely polish the entire blade. At this stage, the hamon's "nieiguchi" (the clarity of the hamon line)—begins to appear.
6. Habaki-moto Polishing
The process of carefully polishing the area above the habaki (the metal fitting at the blade's base)—the region near the nakago often overlooked in standard polishing.
7. Hadsuya (刃艶)
A technique using thin whetstone fragments (small pieces of uchigumo or specialized hadsuya whetstones) run along the edge boundary with a finger in one direction. This is one of the most critical processes for bringing out "the whiteness and brilliance of the hamon"—particularly the glow of nie and nioi near the edge boundary.
The optical difference created here has a metallurgical foundation. The edge of a Japanese sword consists of martensitic microstructure (hardness HRC 60 or higher), while the flat jihada contains mixed pearlite and ferrite structures. These structures have significantly different polishing resistance rates, so even the same whetstone creates different degrees of wear, causing the hamon boundary to appear as visual contrast. By subtly varying the whetstone's application angle, pressure, and direction, the polisher can maximize this structural difference to create a refined expression of the hamon.
8. Jidsuya (地艶)
A technique of applying whetstone fragments to the jihada (flat portion) to polish it. By applying the whetstone at a different angle than in hadsuya work, the jihada grain patterns (itame, mokume, mokume, ayasugi) become distinctly visible. It is no exaggeration to say the beauty of the jihada is determined at this stage.
9. Nuguii (拭い)
A process not involving whetstone polishing but rather using "wiping paper" mixed with pine resin, metal powder, and other materials to polish the entire blade. Performed after jidsuya, this causes the entire blade to take on a blackish tone, allowing the hamon to appear whiter and more vivid in the subsequent hatori work.
10. Hatori Shiage (刃取り仕上げ)
The final stage of edge refinement, making the edge thin and sharp. Thin whetstone plates or specialized "hatori whetstones" are used. When this process is applied to a blade made blackish by the wiping, the hamon appears white and distinct, finalizing the cutting performance and edge beauty.
11. Kissaki and Boushi Polishing (切先・帽子)
The kissaki (blade tip) and boushi (hamon at the tip) are the most complex-shaped regions of the blade and require delicate work using specialized small whetstones. The boushi form (sukikake, maru-boushi, dai-maru-boushi, kaen-boushi, etc.) and hamon clarity are determined at this stage.
12. Final Polishing
The final stage where the overall finish is confirmed and all microscopic scratches created by whetstone polishing are removed. The ideal completed polish is one in which the hamon, jihada, and shinogi all shine in their finest state.
Types of Whetstones Used—From Natural Stones to Synthetic Whetstones
The whetstones used in polishing are broadly divided into "natural whetstones" and "synthetic whetstones." For finish polishing, "natural uchigumo (Kyoto origin)" is considered the highest quality, and in hadsuya and jidsuya processes, "hadsuya fragments and jidsuya fragments created by hand-rubbing individual grains onto steel plates" are employed. Natural whetstone sources are becoming depleted, and obtaining quality stones has become a critical challenge for polishers. Recent years have also seen significant quality improvements in synthetic whetstones, with some processes now achieving finishes comparable to natural stones.
The Japan Art Sword Preservation Society (NBTHK) certifies several hundred polishers nationwide, though among these, highly skilled polishers capable of handling the entire advanced finish polishing process are far fewer. The uchigumo quarries are already severely depleted, and most working polishers manage quality stone procurement and preservation individually. Due to this rarity, the cost of a complete traditional polishing process varies by blade condition and length but often reaches several hundred thousand yen or more.
Conclusion—The 12 Stages of Polishing Complete the Blade's Beauty
The polishing of a Japanese sword is not merely "cleaning" work but an artistic process of "progressively revealing the beauty inherent in the blade." Finish polishing progresses through the sequence of hadsuya → jidsuya → nuguii → hatori, through which the brilliance of the hamon and the grain of the jihada are maximized. Without the polisher's skill, no matter how excellent a blade is at the forging stage, its true beauty cannot be revealed. Deepening understanding of Japanese sword polishing is the first step toward enriching the appreciation of swords and blades.
