Mokume-gane: Wood Grain Metal For Knives
Mokume-gane (Jap 木目金/杢目金, metal textured like wood) is a Japanese technique for making decorative damask from various soft metals. It was originally used for decorating expensive samurai swords. The name of this technique is commonly translated as "metal similar to wood" because of the structure of its pattern, resembling wood bark. The method is believed to have been invented in the 17th century by the Japanese craftsman Denbei Shaomi. Initially he was making swords with a Damascus steel wood pattern, and then he started to make parts with the same pattern for sword handles from softer metals. Three centuries later, jewelers turned their attention to this damascus with its interesting pattern and it gained popularity in the production of jewelry: rings, bracelets, tableware, etc. It has also taken its place in the knife industry and is used on the most expensive knives of outstanding masters all over the world.
The technology of mokume-gane production consists of forming a package of various soft metals: gold, silver, platinum, copper, brass, nisilber and titanium. In Japan, alloys of gold and copper as well as copper and silver were traditionally used. In the production of this damascus, layers of varying thickness are heated to high temperatures and sintered together to form a unique multicolored pattern. Muffle furnaces are used to create the necessary temperature. Then the layers are processed by forging or pressing. Since 2005 a titanium version of damascus with the same design as mokume-gane has been produced - Timasus alloy.
Modern technology of manufacturing damascus from soft metals requires devices such as an electric furnace with a temperature of at least 760 degrees Celsius; a grinding device such as a surface grinding machine, and a pressing machine or forging press. In addition, magnesium oxide in the form of a slurry is needed, which acts as a so-called "releasing agent" to separate the sintered metals from the surface of the machine. Before work, each metal workpiece is cleaned with a dry cloth, running water and alcohol. The metal plates are stacked in the desired order on top of each other and clamped by the press. At this point, the diffusion reaction in the metals is initiated. The package is held under pressure for some time and then placed in a furnace heated between 760 and 820 degrees Celsius. The temperature of the furnace will depend on the materials used in the workpieces. The alloy is kept in the furnace for several hours and then quickly removed and forged under a pressure of 5 to 10 tons. After the press, it is again the turn of the annealing of package of steels, and the cycle annealing-forging is repeated several times. Experienced craftsmen are guided by the color of the heated metal during work, and its changes give them a signal to move on to the next stage of the production cycle. Already in the process of pressing the material, some peeling at the edges of the workpiece becomes noticeable, which can be removed with an electric saw. During the pressing process, the original workpiece is significantly reduced in size. After the forging is finished and the metal is cooled, it is cut into desired shapes using metal saws or cutting wheels.
There are many nuances in making mokume-gane that can lead to spoilage of the workpiece. The main problem is the way to select the required temperature. If the temperature setting is wrong, the metal layers can turn into a monolithic single ingot without forming a clear pattern, and this process will be irreversible and the workpiece will be spoiled. If the temperature is too low, the package will delaminate and the damascus plate will not be forged. Mokume-gane also has an alternative "budget option" in the form of baked polymer clay processed in the damascus style. Precious Metal Clay (PMC) - consists of small particles of various metals mixed with an organic binder. Often the objects created from it are very similar to mokume-gane at a significantly lower cost. In addition, the clay can be processed without sophisticated professional equipment, giving creative freedom to people who do not have a lot of production resources and knowledge of metallurgy.
Mokume-gane has taken its place in the modern knife industry. This material is used to create bolsters and tips for expensive knives with a fixed blade. As well as pads, pins, back spacers and clips on expensive, "custom" folding knives. The damascus made using this technology always gives the knife an expensive appearance and originality. The ancient Japanese metalworking technology has survived through the centuries and is highly prized by knife makers and jewelers today.