Mokume-gane

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Tsuba with a Hawk and a Sparrow, made by Hamano Masanobu, using mokumegane technique Hamano Masanobu - Tsuba with a Hawk and a Sparrow - Walters 51381.jpg
Tsuba with a Hawk and a Sparrow, made by Hamano Masanobu, using mokumegane technique

Mokume-gane (木目金) is a Japanese metalworking procedure which produces a mixed-metal laminate with distinctive layered patterns, as well as that laminate itself. Mokume-gane translates closely to "wood grain metal" or "wood eye metal" and describes the way metal takes on the appearance of natural wood grain. [1] Mokume gane fuses several layers of differently coloured precious metals together to form a sandwich of alloys called a "billet." The billet is then manipulated in such a way that a pattern resembling wood grain emerges over its surface. Numerous ways of working the mokume gane create diverse patterns. Once the metal has been rolled into a sheet or bar, several techniques are used to produce a range of effects. [2]

Contents

Mokume-gane has been used to create many artistic objects. Though the technique was first developed for production of decorative sword fittings, the craft is today mostly used in the production of jewelry and hollowware. [3]

History

Origins

First developed in 17th-century Japan, mokume-gane was 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. [4]

To meet this demand, Denbei Shoami (1651–1728), a master metalworker from Akita prefecture, invented the mokume gane process. He initially called his product guri bori for its simplest form's resemblance to guri, a type of carved lacquerwork with alternating layers of red and black. Other historical names for it were kasumi-uchi (cloud metal), itame-gane (wood-grain metal), and yosefuki. [5]

The early components were relatively soft metals and alloys (gold, copper, silver, shakudō, shibuichi, and kuromido) 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. [4]

Over time, the practice of making mokume gane faded. The katana industry dried up in the late 19th century with Meiji Restoration returning ruling power to the emperor and 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 in mokume gane along with most other sword related artisans largely transferred their skills to create other objects. [3]

The West, 1877-

Tiffany & Co.'s silver division under the direction of Edward C. Moore began to experiment with mokume gane techniques around 1877 and at the Paris exposition of 1878 Tiffany's in its grand prize-winning display of Moore's "Japanesque" silver wares included a magnificent "Conglomerate Vase" with asymmetrical panels of mokume gane. (The Conglomerate Vase which has been widely acclaimed as the most important work of nineteenth-century American silver was sold at Sotheby's on January 20, 1998 for $585,500.) Moore and Tiffany's silver smiths continued to develop its popular mokume techniques in preparation for the Paris exposition of 1889 where it displayed a vast array of Japanesque silver using ever more complex alloys of shakudō, sedo and shibuichi 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 mokume up into the twentieth century. [6]

20th-21st century development

By the mid 20th century, mokume gane was almost entirely unknown. Japan’s movement away from traditional craftwork, paired with the great difficulty of mastering the mokume gane art, had brought mokume gane artisans to the brink of extinction. It reached a point where only scholars and collectors of metalwork were aware of the technique. [4] It was not until the 1970s, when Hiroko Sato Pijanowski who learned the craft from Norio Tamagawa. Hiroko and her husband Eugene Pijanowski brought the craft of mokume gane back to the United States and began teaching it to their students, at this point the artform re-emerged in the public eye.

Today, jewelry, flatware, hollowware, spinning tops and other artistic objects are made using this material. [3]

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. [4] 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 mokume gane materials, along with new possibilities for laminating metals such as the use of friction-stir welding.

Techniques

Mokume-gane brass/copper billet Mokumebillet.png
Mokume-gane brass/copper billet
Example of Mokume-gane patterns in gold and silver alloys Gold Mokume.png
Example of Mokume-gane patterns in gold and silver alloys

Liquid Phase Fusion (historic)

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 the traditional 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. [4]

Soldering (brazing)

In attempting to recreate the appearance of traditional mokume gane 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. Flux inclusions could be trapped or bubbles could form. Commonly, imperfections need to be cut out, and the metal re-soldered. Ultimately the brazed sheets do not display the ductility and work-ability of diffusion bonded material.

Solid-state bonding (contemporary)

The modernized process 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. [4]

Development of the mokume pattern

After the fusion of layers, 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. [5]

Coloring

To increase the contrast between the laminate layers many mokume-gane 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.

Niiro patination and rokushō

One example of a traditional Japanese patination for mokume-gane is the use of the niiro process, usually involving rokushō, 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 is applied immediately before the piece is boiled in the rokushō to protect the surface against tarnish and uneven coloring. [5]

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 mokume-gane could have many more.

See also

Related Research Articles

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Brazing High-temperature soldering; metal-joining technique by high-temperature molten metal filling

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<i>Shakudō</i> Japanese copper and gold alloy

Shakudō (赤銅) is a Japanese billon of gold and copper, one of the irogane class of colored metals, which can be treated to develop a black, or sometimes indigo, patina, resembling lacquer. Unpatinated shakudō visually resembles bronze; the dark color is induced by the niiro artificial patination process, involving boiling in a solution, generally including rokushō.

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Rokushō (緑青) is a traditional Japanese chemical compound used in the niiro process for artificially inducing patination in decorative non-ferrous metals, especially several copper alloys, with the results being metals of the irogane class. These "colour metals," virtually unknown outside Japan until the late 19th century, have achieved some popularity in craft circles in other parts of the world since then.

<i>Shibuichi</i> Historically Japanese copper alloy

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Kuromido is an historically Japanese copper alloy, typically of 99% copper and 1% metallic arsenic, one of the class of irogane metals.

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Colored gold

Pure gold is slightly reddish yellow in color, but colored gold in various other colors can be produced.

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Titanium ring

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Copper in architecture

Copper has earned a respected place in the related fields of architecture, building construction, and interior design. From cathedrals to castles and from homes to offices, copper is used for a variety of architectural elements, including roofs, flashings, gutters, downspouts, domes, spires, vaults, wall cladding, and building expansion joints.

Cóilín Ó Dubhghaill is an Irish artist and academic, crafting as a silversmith and also in copper and Japanese-inspired copper alloys, gold and other metals. He lived in Japan and studied Japanese metal crafts for seven years in the national arts university. His art is held in a range of national and other museums and galleries, and has been widely shown. His research work bridges art and materials science, and he is co-inventor of a new hybrid metal, mikana.

Irogane is the term for a set of Japanese metals – forms of copper, and copper alloys – treated in niiro patination processes, traditionally used in sword-making, catches for sliding doors, and luxury highlights on larger objects, and in modern times, in jewellery. The alloys contain two to five metals. Some scholars believe that methods similar to those involved in irogane production may also have been used in ancient Egypt and the Roman world, as well as China and Tibet (dzne-ksim).

Niiro, also known as niiro-eki (煮色液), niiro-chakushoku (煮色着色), nikomi-chakushoku (煮込み着色) or niage (煮上げ) is an historically Japanese patination process, responsible for the colouration of copper and certain of its alloys, resulting in the irogane class of craft metals, including shakudo, shibuichi and kuromido. It is now practiced in a number of countries, primarily for the making of jewellery and decorative sword fittings, but also for material for hollowware and sculpture. Importantly, the same process operates differently on different metals so that a piece with multiple components can be treated in one patination session, developing a range of colours.

References

  1. Midgett, Steve (2000). Mokume Gane A comprehensive study. earthshine press. ISBN   0-9651650-7-8.
  2. "Blog Article Mokume Gane". Larsen Jewellery. 2016. Retrieved 2016-04-08.
  3. 1 2 3 "About Mokume Gane". Andrew NYCE Designs. 2002. Retrieved 2015-02-10.
  4. 1 2 3 4 5 6 Binnion, J. E. & Chaix, B. (2002). "Old Process, New Technology: Modern Mokume Gane". Archived from the original (PDF) on 2009-08-29. Retrieved 2007-01-26.Cite journal requires |journal= (help)
  5. 1 2 3 Pijanowski, H.S. & Pijanowski, G.M. (2001). "Wood Grained Metal: Mokume-Gane" . Retrieved 2007-01-26.Cite journal requires |journal= (help)
  6. Loring, John (2001). Magnificent Tiffany Silver. Harry N. Abrams. ISBN   0-8109-4273-9.

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