Mokume Gane

This is a traditional Japanese technique of diffusion welding precious and nonferrous metals. The result is a Damascene-like composite which can produce all the patterns known from pattern-welded steel, such as random or controlled layered patterns or torsion patterns. Mokume Gane is much more sensitive to internal stresses than layered steel, resulting in cracks especially on the edges.

Mokume Gane, literally translated Wood-Gained-Metal, has been developed by Denbei Shoami (1651 - 1728) in ancient Japan. Shoami is actually the highest title given by the Shoam-School, one of the 5 Japanese Sword Schools. The privilege of using this title proves the outstanding talents of Denbei Shoami who has created remarkable artifacts in many fields of arts and crafts.

Mokume Gane Bowl

Bowl of Mokume Gane (K. Loose)

Mokume Gane has often been used for hilts and tsubas but was also used for precious metal containers and other artifacts. Today Mokume Gane is a soughtafter material for jewelry, and is being used by some artists for knife-handles and other objects.

Producing Mokume Gane

It is not possible to diffusion weld nonferrous metals by hammer since they cannot be easily freed from their oxide-skin by fluxes. It is necessary to heat oxide-free layers under high pressure to receive a proper diffusion weld.

The sheetmetal pieces have to be freed from grease, oxides and dirt when preparing to weld a Mokume Gane. Scotch Brite with soapy water is suited for this work. The sheet metal pieces are air-dried thereafter and may not be touched by bare hands.

The cleaned sheets are stacked according to the desired order. Caution has to be taken not to stack 2 sheets of the same metal upon each other, since this will cause a weak bond. The whole package is then placed into the "press" after being wrapped into a singe layer of paper to prevent it from sticking to the press. This press is made from 2 thick steel plates with several heavy screws, ideally from high temperature steel. High temperature grease should be used to prevent the screws from getting stuck. By tightening the screws, the packet of Mokume Gane is pressed. The whole is then placed into the fire furnace.

The combination of high pressure and temperature causes a diffusion weld between the sheets of metal. The lowest eutectic melting point of all present metal combinations limits the maximum permissible temperature. The temperature actually applied should stay about 10° to 20°F below the eutectic melting temperature which is always below the melting temperature of the metals used. When the eutectic melting temperature is reached small droplets of liquid metal are observed on the edges of the Mokume Gane packet. It looks as if the metal is sweating. Further heating will result in melting the entire packet.

When using more than 2 different metals, it is helpful if the eutectic melting point of all present combinations is located in a similar range. This way all bonds will have similar strength.

Cheating Techniques

By hard-soldering sheet metal, a compound similar to Mokume Gane is produced. The bond is produced by solder flowing, driven by capillary action, into the spaces between the layers. This generally causes wider alloyed zones, characterized by distinctly different mechanical properties. Often the solder is more brittle than the adjacent metals. It is hard to impossible to twist Mokum Gane produced by cheating techniques.

Working with Mokume Gane

Mokume Gane should be forged in the range between room temperature and black heat (when no heat color is visible). While forging the work, hardening is felt very pronounced; heating to dull red will soften the metal again. Special caution has to be taken while controlling the pattern.

Many nonferrous metals produce a translucent oxide layer. Often a shimmering effect can be produced by heat-oxidation. Copper can show a violet color caused by light refraction. The colors created by nonferrous metals are not as distinct as known from titanium. Anodizing titanium is also an oxidation, caused by a chemical process, driven by electric forces and not by heat.

Mokume Gane Rings

Rings made of Mokume Gane

© 2005 G.v.Tardy