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The earliest Tsuba were generally flattened disks made of  bronze or copper. They were superceeded by the Chinese style cross guard between the 6th and 9th centuries only to be returned to favor as plain iron disks with minimal decoration in the 12th century. The early iron(tetsu) tsuba was made by armourers who were able to apply their skills at making plate to good effect. Notice there are no cutouts for the kosuka and kogai.

Though piercing was employed as a means of lightening, the plain iron guard represents the functional apex of tsuba making. Usually the best iron was used in their construction and considerable effort expended in shaping and texturing the material. Sometimes the  tsuba was simply forged to shape and left at that. No further finishing was required  as a pleasing design could be achieved with skillfull forging alone.

Decoration if any was simple and generally confined to a simple punched or forged indentation. The handle side was generally more decorated than the blade side. The round silver mon (familycrest) on this example is a later addition. (The mon indicates that this was a sword of the Ogasawara Clan.) The rounded square shape is known as kaku gata. The iron would be patinated to a pleasing black color which preserved it from further oxidation. Or it would sometimes be allowed to rust to a degree before being stabilised to a russet color.

A tsuba maker named Masatsugu Ito took piercing to the limit. He could simulate a piece of string attached to a kite for instance. He must have enjoyed the visual pun as his name, Ito, means string. Some of his work was extremly complex and very precise. He founded a school that bears his name. He used to drill a very tiny hole in the guard then he would coat a piece of steel wire with carburundum or ruby powder and pass it back and forth through the hole until it became elongated into a line.

Piercing was taken to an extreme on occasion so that it threatened the structural integrity of the guard. Weight was a factor in tsuba design such that Lord Shingen was said to have extoled the virtues of a certain guard for its lightness and strength. The guard he referred to was an iron lattice interwoven with wire. The one shown has a copper body with gold fill and surface color. It would not have withstood the impact of a good hit and would probably have been reserved for formal occasions. It was not uncommon for a sword to have more than one set of koshirae..

Inlaying of soft metals such as gold, silver, copper or brass alloys became prevalent in the 14th century. Initially inlaying utilised the baser metals and a degree of crudity in execution. A depression was cut in the surface by chisel. The sides of the depression are burred up while the sides of the inlay are beveled. The inlay is also domed slightly so it has a smaller footprint. Once the inlay is in situ the dome is flattened to spread it into the depression and the burr is pressed back down trapping it in place. By the end of the fourteenth century raised inlays were used so that they could be relief carved.

In other surface techniques a chisel was used to create a crosshatch pattern in the parent metal then a layer of gold foil was laid on the pattern and hammered into it with a wooden punch after which it is burnished. Another method involved using thin wire and small pieces of soft metal fused directly into the surface to create detail. Overlays were also created by fire gilding an amalgam of soft alloy and mercury into the surface. The heat drives off the mercury leaving the gold or other metal fused to the iron. Thats how they got the coppery color on the surface of those WW11 brass koshirae.

The use of alloys such as shakudo, shibuichi, as well as copper, brass, bronze, gold and silver together allowed color and contrast to become an overiding factor in decorative techniques toward the end of the fifteenth century. Most metals were designed for patination except for steel, silver and gold. Even silver was frequently patinated or simply allowed to blacken naturally. Texture was also a vital element of the visual effect. Chisling was used to make fine lines in parallel for shading and detail. Punches were used to create fine texture like paper, pigskin, stone and "fish roe". The side of the tsuba facing the grip was usually the more decorated

Even in times of war there were always some tsuba which were more for show than for action. With the accession of the Tokugawa shogunate such tsuba became more commonplace and decoration began to take an ever increasing role in the making of tsuba. Techniques reached new heights. Yujo Goto in the 16th century is frequently credited for this. The workmanship of many guards from this time is often astonishing in its conveyance of detail, texture, color and contrast. Its probably fair to say that these tsuba represent the finest soft metal work of all time.

As time goes by however we see more and more tsuba with the body made entirely in soft metals such as copper or shakudo. The more frequent use of the all soft metal body represented a decadence in the art because it no longer had the functional integrity of battle tested iron. Decline was accelerated in the mid ninteeth century when the Samurai class was abolished. Many tsuba makers drifted into other persuits such as making knick knacks for the tourist trade.

By the time World War 11 rolled around the majority of guards were made entirely out of brass in government factories. Ironically these were based on an early pattern. They tend to be heavy for the amount of protection they afford, but they are nice to look at. Ironicaly also a police saber of the time, which was little more than an iron bar, carried a mild steel tsuba which was chrome plated and much closer conceptually to the real thing. Today high quality Tsuba are still made by individuals in Japan though the art no longer has as many practicioners as it once had.