Mokume-gane

History

Origins

First developed in 17th-century Japan, ja was originally used for swords. As the customary Japanese sword stopped serving as a weapon and became largely a status symbol, a demand arose for elaborate decorative handles and sheaths.{{cite journal |name-list-style = amp |access-date = 2007-01-26 |url-status = dead |archive-url = https://web.archive.org/web/20090829004018/http://www.mokume-gane.com/Papers/PaperThankyou.html |archive-date = 2009-08-29

To meet this demand, Denbei Shoami (1651–1728), a master metalworker from Akita prefecture, invented the ja process. He initially called his product ja, as the technique in its simplest form resembled ja, a type of carved lacquerwork with alternating layers of red and black. Other historical names for it were , , and ja.{{cite journal |name-list-style=amp | title = Wood Grained Metal: Mokume-Gane | access-date = 2007-01-26 }}

The early components of ja were relatively soft metals and alloys (gold, copper, silver, ja, ja, and ja) which would form liquid phase diffusion bonds with one another without completely melting. This was useful in the traditional techniques of fusing and soldering the layers together.

Over time, the practice of ja faded. The katana industry dried up in the late 19th century, with the Meiji Restoration returning ruling power to the emperor, following the dissolution of the shogunate government and the end of the samurai class. The public display of swords as a sign of samurai status was outlawed. After this, the few metalsmiths who practiced ja along with most other sword related artisans largely transferred their skills to create other objects.

Adoption of {{transliteration|ja|mokume-gane}} in the West

Tiffany & Co's silver division under the direction of Edward C. Moore began to experiment with ja techniques around 1877, and at the Paris exposition of 1878, Tiffany's grand prize-winning display of Moore's "Japanesque" silver wares included a magnificent "Conglomerate Vase" with asymmetrical panels of ja. Moore and Tiffany's silver smiths continued to develop its popular ja techniques in preparation for the Paris exposition of 1889, where it displayed a vast array of Japanesque silver, using ever more complex alloys of ja, ja and ja, along with gold and silver, to make laminates of up to twenty-four layers. Tiffany's display again won the grand prize for silver wares, and the company continued to produce its Japanesque silver with ja techniques up into the 20th century.

20th-21st century development

By the mid 20th century, ja had fallen into heavy obscurity. Japan's movement away from traditional craftwork, paired with the great difficulty of mastering ja, had brought ja artisans to the brink of extinction. It reached a point where only scholars and collectors of metalwork were aware of the technique. It was not until the 1970s, when Hiroko Sato Pijanowski – who learned the craft from Norio Tamagawa – that the craft was reignited in the public eye, as Hiroko and her husband Eugene Pijanowski brought the craft of ja back to the United States and began teaching it to their students.

Present day

Today, jewelry, flatware, hollowware, spinning tops and other artistic objects are made using ja.

Modern processes are highly controlled and include a compressive force on the billet. This has allowed the technique to include many nontraditional components such as titanium, platinum, iron, bronze, brass, nickel silver, and various colors of karat gold including yellow, white, sage, and rose hues as well as sterling silver. At the Santa Fe Symposium, a major annual gathering of jewelers from around the world, there have been several papers presented on new, more predictable, and more economic, methods of producing ja materials, along with new possibilities for laminating metals such as the use of friction-stir welding.

Techniques

Liquid phase fusion (historic)

In liquid phase fusion, metal sheets were stacked and carefully heated; the solid billet of simple stripes could be forged and carved to increase the pattern's complexity. Successful lamination using this process requires a highly skilled smith with a great deal of experience. Bonding in the traditional process is achieved when some or all of the alloys in the stack are heated to the point of becoming partially molten (above solidus) this liquid alloy is what fuses the layers together. Careful heat control and skillful forging are required for this process.

Soldering (brazing)

In attempting to recreate the appearance of traditional ja, some artisans tried brazing layers together. The sheets were soldered using silver solder or some other brazing alloy. This technique joined the metals, but is difficult to perfect, particularly on larger sheets, because flux inclusions can get trapped or bubbles could form. Commonly, these imperfections need to be cut out, and the metal re-soldered. In addition, brazed sheets also do not display the same levels of ductility and work-ability of diffusion-bonded material.

Solid-state bonding (contemporary)

The modernized process of solid-state bonding typically uses a controlled atmosphere in a temperature-controlled furnace. Mechanical aids such as a hydraulic press or torque plates (bolted clamps) are also typically used to apply compressive force on the billet during lamination. These provide for the implementation of lower temperature solid-state diffusion between the interleaved layers, thus allowing the inclusion of non-traditional materials.

Development of the {{transliteration|ja|mokume-gane}} pattern

After the layer fusion, the surface of the billet is cut with chisel to expose lower layers, then flattened. This cutting and flattening process will be repeated over and over again to develop intricate patterns.

Coloring

To increase the contrast between the laminate layers, many ja items are colored by the application of a patina (a controlled corrosion layer) to accentuate or even totally change the colors of the metal's surface.

{{transliteration|ja|Niiro}} patination and {{transliteration|ja|rokushō}}

One example of a traditional Japanese patination for ja is the use of the ja process, usually involving ja, a complex copper verdigris compound produced specifically for use as a patina. The piece to be patinated is prepared, then immersed in a boiling solution until it reaches the desired color, and each element of a compound piece may be transformed to a different color. Historically, a paste of ground daikon radish was also used to prepare the work for the patina. The paste was applied immediately before the piece is boiled in the ja to protect the surface against tarnish and uneven coloring.

Similar laminates

In an accidental but parallel development, Sheffield plate was developed in England. It follows a similar principal of bonded layers, without use of solder, but typically had 2–3 layers, whereas ja could have many more.

References

References

1. Midgett, Steve. (2000). "Mokume Gane A comprehensive study". earthshine press.
2. (2002). "About Mokume Gane".
3. Loring, John. (2001). "Magnificent Tiffany Silver". Harry N. Abrams.
4. [http://galleryjapan.com/locale/en_US/artist/2472/ Norio Tamagawa]