Suriage (Blade Shortening) Technology and Appraisal—Sword Modification from Tachi to Uchigatana, Value Assessment, and Identification Methods

What is Suriage? — Blade Modification Born from Changes in the Times

"Suriage" (polishing-up) is one of the modification practices that changes the form of a Japanese sword, specifically referring to the process of shortening the overall length of the blade (including the cutting edge length) by trimming down the rear end of the blade's nakago. Through suriage, the cutting edge length also becomes shorter, and as the nakago portion becomes shorter, the grip (tsuka) and overall blade balance change, with the modification most often carried out for the purpose of improving practical usability.

As for the etymology of the term "suriage," the general explanation is that it derives from the process of finishing and polishing (polishing-up) the cut surface of the nakago.

The historical background behind large-scale suriage lies in the fact that large tachi blades manufactured during the Kamakura to Nanbokucho periods became difficult to use as warfare tactics changed (from mounted combat to foot soldier combat). Long tachi blades were not suited to the style of being worn at the waist as uchigatana, and it became common practice to reuse them as uchigatana by trimming and shortening the nakago. From the late Muromachi period through the early Edo period, many masterpieces of koto blades were suriaged and used as uchigatana.

Types of Suriage — Classification by Amount of Tang Trimming

Suriage is classified as follows based on the degree of modification.

Small Suriage (ko-suriage)

The amount of nakago trimming is relatively small, with a portion of the original nakago remaining. In most cases, the original signature (the original swordsmith's mei) is preserved, and some of the original mekugi holes also remain. Part of the file marks (yasurime) of the nakago can be seen continuing.

Large Suriage (ō-suriage)

The nakago has been trimmed substantially. The original signature (mei) is often partially or completely lost. The original mekugi holes have been removed, and new ones have been drilled. The overall form of the nakago has changed.

Complete Suriage (kanzenzn-suriage)

The original nakago has been completely removed, with the original signature completely lost. The entire nakago has been newly formed after the time of suriage. The original file marks do not remain, and new file marks have usually been applied.

Treatment of the Signature (mei) — Wrapped Signatures and Appraisals

When performing suriage, how the original signature is handled becomes an extremely important issue in appraisal.

Wrapped Signature (orekae-shi-mei)

When the original signature remains on a specific part of the nakago, the practice of folding back the end of the trimmed nakago to preserve the part where the signature is inscribed is called a "wrapped signature" (orekae-shi-mei). Through this, the original signature remains hidden inside the shortened nakago. The presence of a wrapped signature is an important positive factor in appraising the value of a suriaged blade.

Whether a wrapped signature exists can be confirmed by carefully examining the area around the mekugi holes and the sides and ends of the nakago when removing the tsuka and observing the nakago.

Added Signature (soe-mei) / Daimyo Signature

After suriage, a daimyo or sword merchant who commissioned the suriage may add their own name as a signature on the nakago. This is called an "added signature" (soe-mei) or "daimyo suriage" (daimyo-suriage). In famous blades that are said to have been suriaged by renowned warlords such as Toyotomi Hideyoshi, Tokugawa Ieyasu, and Date Masamune, such added signatures may remain.

Appraisal (kiwame) and Later Signature (nochi-mei)

When later sword appraisers (such as the Honami family) apply a signature as an appraisal result on a suriaged blade that has lost its original signature, this is called an "appraisal" (kiwame) or "entering a later signature" (nochi-mei wo ireru). Suriaged blades bearing appraisal signatures from famous appraisers such as Honami Koōon and Honami Kōchū possess historical value in themselves.

Characteristics of the Tang After Suriage — Identification in Appraisal

A suriaged blade can be confirmed by observing the nakago. The characteristic features seen in suriaged nakago are as follows.

• Appearance of Tang Tip (Cut Surface): The nakago tip that has been cut during suriage often has a different shape from the original nakago tip. The nakago tip of the original tachi often has a long, thin form called "sword-shaped (kengate) nakago" or "fine nakago (hoso-nakago)," but this characteristic shape is lost after suriage.
• Multiple Mekugi Holes: In suriaged blades, the original mekugi holes and newly drilled mekugi holes after suriage may coexist. When old mekugi holes remain near the nakago tip and new mekugi holes are located near the connection point with the tsuka, this becomes evidence that suriage was performed.
• Discontinuity in File Marks (yasurime): When the pattern of file marks on the original nakago changes partway through or is unnaturally cut off, this indicates that the original nakago was cut by suriage and new file marks were applied to the remaining portion.
• Changes in Tang Thickness and Cross-Section: The original tachi nakago is often relatively thin and flat, but when the nakago is reshaped as an uchigatana nakago after suriage, the cross-sectional form may change.

The procedure for reading the overall history of a blade from its file marks, mekugi holes, and signature is systematically explained in The Complete Guide to Reading Tangs (nakago).

Impact of Suriage on Blade Value

Suriage has a complex impact on the value appraisal of Japanese swords.

Negative Factors:

• Loss of the original signature
• Loss of the original nakago form
• Alteration from the original manufacturing state
• Increased polishing history

Particularly when the original signature is lost in complete suriage, even if an appraisal signature exists, the evidentiary power as to the original blade weakens.

Positive Factors or Neutral Aspects:

• Blades that have been suriaged by historically renowned figures (Toyotomi suriage, Tokugawa suriage, etc.) gain added value from their historical provenance.
• When a wrapped signature has been preserved, it contributes to value retention.
• If the blade body (cutting edge length) shows good integrity and quality, it is appraised separately from the nakago condition.

Distinguishing Authentic Suriage from Later Fraudulent Modifications

Appraisal points for distinguishing authentic suriage from the Muromachi to early Edo period from later fraudulent modifications (false suriage) performed for improper purposes:

• Consistency of Age Patina (Rust Color): For authentic suriage, the rust that has developed over the years since the time of suriage is uniformly distributed across the entire nakago. In fraudulent suriage (modern modification), the color and quality of rust are unnaturally different from other parts of the blade and nakago.
• File Mark Technique and Tool Traces: The tool traces and processing precision differ between pre-Edo period file marks and modern file marks. File marks that are unnaturally too clear warrant careful attention.
• Stylistic Consistency of Tang Form: Verification that the post-suriage nakago form is consistent with the "nakago form of the era and school in which the blade was manufactured." If it is not consistent, suspicion of later modification arises.

Suriage is a modification culture that arose necessarily in the history of the Japanese sword, and in itself represents the demands of the era and the skill of the swordsmith. For appraisers, observing a suriaged blade is also a task of reading multiple historical cross-sections at once, from the era of its creation through the era of modification and down to the present day.