Mokume-gane
From Wikipedia, the free encyclopedia
Mokume-gane ( 木目金 ) is a mixed-metal laminate with distinctive layered patterns. Literally translating as "wood eye (i.e., burl) metal", the name was borrowed from one type of pattern created in the forging of swords and other edged weapons.
First made in 17th-century Japan, the mixed-metal was used only for sword fittings until the Meiji era, when the decline of the katana industry forced artisans to create purely decorative items instead. The inventor, Denbei Shoami (1651-1728), 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-gaine (wood-grain metal), and yosefuki. (Pijanowski & Pijanowski, 2001)
The traditional components were relatively soft metallic elements and alloys - gold, copper, silver, shakudo, shibuichi, and kuromido - which would form liquid phase diffusion bonds with one another without completely melting. After the original metal sheets were stacked and carefully heated, the solid billet of simple stripes could be hammered flat and folded to increase the pattern's complexity.
The modernized process typically uses a controlled atmosphere in a temperature controlled electric furnace. A hydraulic press is also used to apply far more force than hand-forging and induce lower temperature solid-state diffusion between the interleaved layers, allowing the inclusion of 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. (Binnion & Chaix, 2002)
[edit] Coloring
To color the shakudo and gold, submerse the piece in boiling rokusho, and hold there - agitating constantly - until it reaches the desired color. Rokusho colors shakudo a black-purple. The more gold is in the alloy the more purple it turns. Rokusho is a solution of 6 g cupric acetate, 1.5 g copper sulphate, table salt in 1 L of distilled water.
Some people used a paste made of ground daikon radish. The recipe is the following; 1 part Daikon radish to 5 parts water, ground with a mortar and pestle.
The paste is applied immediately before the piece is boiled in the rokusho to protect the surface against tarnish and uneven coloring. After the coloring process is over, the finished piece is waxed. (Pijanowski & Pijanowski, 2001)
Shakudo can also be darkened by adding salt with ammonia in a plastic bag. The warmer the solution the faster it will darken the metal.
[edit] See also
[edit] References
- Pijanowski, H.S. and Pijanowski, G.M. (2001). "Wood Grained Metal: Mokume-Gane". Retrieved on 2007-01-26.
- Binnion, J. E. and Chaix, B. (2002). "Old Process, New Technology: Modern Mokume Gane" (PDF). Retrieved on 2007-01-26.
