MOKUME GANE
Mokume Gane – Mokume (literally „wooden eyes“) means „wood grain“ and Kane means „metal“.
HISTORY
The forging technique of mokume gane was developed in feudal Japan in the 16th century. At that time, it was handed down from master to student as a well-kept secret. To this day, the swordsmith Denbei Shoami (1651-1728, Akita, Japan) is seen as the creator of the technique.
Due to their Japanese origin, the metals used have exotic names such as shibuishi, shakudo and kuromido. They describe the colour of these copper alloys after patination. In combination with pure copper and fine silver, they were used to make sword guards, known as tsuba. Such art objects were used to decorate precious samurai swords and were also a status symbol for the owner.
Consequently, the art of swordsmithing influenced all forms of metalworking in Japan. As soon as craftsmen began to forge other decorative objects such as bowls, vases and boxes from mokume gane. One of the most famous master craftsmen forging vessels from welded layered metals was Hirotoshi Itoh. His description of working with mokume gane also expresses my philosophy of goldsmithing.
»Work always from the heart. Love the hammer, let every blow gently knead the metal … listen to the metal and do not make it cry. Love the metal, and it will love you back.«
Hirotoshi Itoh
TRADITION AND PRESENCE
In the 1970s, the Japanese forging technique came to the USA and thus to the western world. The married couple Gene Pijanowski and Hiroko Sato learnt about the classic copper-based mokume gane at an exhibition in Tokyo. Inspired by the possibilities of the material combinations, they further developed the technique for the jewellery sector. They were the first to use precious metals instead of copper alloys. This created pieces of jewellery that are ideal for daily wear directly on the body. Alloys based on copper lose their beauty over time. Precious metal layered sheets, on the other hand, are durable and chemically resistant.
DIFFUSION WELDING
The starting material for the technique is always stacks of metal sheets in contrasting colours, which are joined in various ways. Either by soldering the individual sheets or by welding them together with an open flame. I decided in favour of the third method as it offers controlled conditions and many material combinations are possible. I join precious metals by diffusion bonding in a laboratory furnace.
Für Schmuckstücke, wie Trauringe aus Mokume Gane, bei denen die Maserung direkten Kontakt mit der Haut hat verwende ich ausschließlich Edelmetallegierungen.
What is diffusion bonding?
First, the different layers of different alloys are cleaned and degreased so that they bond better later. The stack of sheets to be welded is then pressed between two steel plates. Screws keep this stack under pressure during the entire firing process. To prevent the metals from oxidising, I wrap the package in steel foil and add some coal. As a result, an oxygen-reduced atmosphere develops inside. The billet spends several hours in the furnace, whereby the alloys are only heated to just under their melting point. New crystalloids form on the contact areas of the sheets. They diffuse to form a thin layer, a new alloy. Although this bond is still very fragile at the beginning of the hammering process, it stabilises through repeated forging and annealing.
For pieces of jewellery, such as wedding rings made from mokume gane, where the metal is in direct contact with the skin, I only use precious metal alloys.
- Sterling silver
- Palladium
- White gold
- Champagne-coloured gold
- Rose gold
- Yellow gold
- Green gold
