Ieyasu Tokugawa's armor hardware-a goldsmith approaching the mystery of jet black-April 21, 19:37

A new history museum will open in Shizuoka City to coincide with the big river drama "Dousuru Ieyasu" that will be broadcast next year.

The biggest attraction is the national important cultural property, which is being newly produced using the materials and techniques of the time. Shidagusoku) ".

The hardware is made of jet black, which is said to have been difficult with the technology of the time.

The mystery of how the hardware was made was revealed by a goldsmith in Kofu City.

(Akihiko Iida, reporter of Kofu Broadcasting Station)

Jet-black armor Ieyasu's toothpaste

The Battle of Sekigahara was a major milestone for Ieyasu Tokugawa to unify the world.

It is said that he wore a jet-black armor and tōseigusoku.

During the Warring States period, colorful and gorgeous armor was the mainstream to show martial arts on the battlefield, but the jet-black color is said to be a symbol of the world and Ieyasu, and is designated as an important cultural property of the country.

Efforts have begun to create this tōseigusoku with the materials and techniques of the time and display it as a feature of the history museum that will open in Shizuoka City in January next year.

The technique of a goldsmith brought up in the jewelery town of Kofu

Mr. Masaki Hosaka, a goldsmith in Kofu City, is in charge of restoring the hardware of the tōseigusoku.

Mr. Hosaka was born and raised in Kofu City, one of the leading jewelery towns in Japan.

Many jewelery makers and craftsmen gather to produce about one-third of the jewelery distributed in the country.

Born in a jewelery craftsman's family, Mr. Hosaka took over the family business after graduating from university, but his high technical skills were recognized and he became involved in the restoration of armor hardware as a metal engraver.

A goldsmith is a craftsman who uses a traditional tool called "tagane" to decorate metal.

The charm of restoring armor facing the craftsmen of the time

The turning point for Mr. Hosaka, who started his career as a metal engraver, was the restoration of the national treasure of Yamanashi, the hometown of Yamanashi.

It is said that he was fascinated by the way of life and commitment of Kai Genji's ancestor, Minamoto no Yoshimitsu, and the restoration while imagining the techniques and hardships of the engraver who created it.

Mr. Masaki Hosaka

"For a military commander, armor is like a shroud. It is made by combining the best techniques of the time. I feel that being involved in it is attractive."

It's been about 10 years since then.

The technique of restoring a lot of hardware was highly evaluated, and Mr. Hosaka was entrusted with the restoration of the hardware of the tōseigusoku.

Verification of the technique of tōseigusoku jet black

Hardware is made by connecting plates made of leather or iron, or by carving a fine pattern on the surface to make the armor gorgeous.

For this reason, many of them have flashy colors such as gold and silver, but the hardware of the tōseigusoku is black, and it is characterized by a deep black like lacquer.

Difficult “black” first scientific approach

According to Mr. Hosaka, it was technically difficult to make the hardware black at that time.

The technique called "red copper", which mixes gold with copper that remains in the literature, could only express bluish black.

For this reason, Mr. Hosaka decided to verify with Tokyo University of the Arts how he produced black.

Therefore, when analyzed using a device that examines the metal content and composition, it was found that copper contains a trace amount of silver.

Approach the mystery of jet black with "silver"

Based on this analysis, Mr. Hosaka started an experiment to restore jet black.

In the experiment, we used a technique called "hot water blowing" at that time, and poured the metal melted in a crucible heated to 1000 degrees or more into hot water to make a lump.

While repeating the production of hardware while changing the amount of silver added, it was also found that if too much silver was added, it would appear on the surface and would not turn black.

After about four years of trial and error, we arrived at 2% silver.

It was discovered that when the finished iron plate is dipped in sulfur melted in hot water at 60 degrees Celsius, it changes to jet black due to the sulfurization reaction.

According to Mr. Hosaka, the technique of putting silver in copper to make hardware jet black has not been found so far.

Restoring jet-black hardware with new techniques

Mr. Hosaka who elucidated the technique at that time.

Restoration has finally begun in earnest.

The pattern made by the craftsman is faithfully reproduced using a chisel.

I will add a pattern of "arabesque" and "nanako" in the shape of fish eggs.

When the sulfurization reaction was applied to the finish, the first metal fitting was completed.

Mr. Hosaka

"I want to share the thoughts and aesthetics of Ieyasu and the thoughts of the craftsmen who were involved in the production of armor, and mobilize all my skills and knowledge for restoration production."

Is it an overseas technology?

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Expectations for new research progress

The armor was made by the people in power at the time by gathering the best techniques, materials, and human resources, and it is a valuable material that traces the history.

However, since it is a sacred thing that the military commander wore when he faced the battle for his life, it was carefully preserved in museums and so on, and scientific research has hardly been done.

This time, by investigating the hardware of Ieyasu's tōseigusoku with a scientific approach and discovering a new technique, research on armor and metal products used at that time progressed, and the era when Ieyasu lived in more detail. Historian Masaru Hirayama evaluates that it may lead to knowing.

Masaru Hirayama

"I think it was a discovery on a large scale that spreads research, whether the technique of using silver was originally created in Japan, or whether overseas technology was imported and used for armor. I look forward to the spread of international trade and the progress of armor research at that time. "

If foreign technology was used for the hardware of Ieyasu's armor, it could be said that it was a great discovery to know the new facts at that time.

I hope that this survey will lead to the progress of research in this era.

Kofu Broadcasting Station Reporter

Akihiko Iida

Since November 2021, he has been

interviewing jewelry and wine in order to convey the charm of Yamanashi Prefecture

.

Impressed by the unexpected connection between the local hero Ieyasu Tokugawa and the engraver in Kofu