The Korean technique of Keum-boo translates to "gold added." It is a way to apply 24k gold to fine silver and was used in various Asian cultures to adhere gold to iron, steel, and copper. The Korean method is also spelled kum-bu.
The Keum-boo process involves depletion silvering a flat sterling piece (bring up the fine silver) by repeated heating, quenching, and pickling until it is completely white. Then the piece is heated to 650 degrees F on a hot-plate. 24k gold foil is placed on the piece and burnished in place. These pieces can then be used in the fabrication of jewelry. The finished piece may be patinated, polished, or left white.
In feudal Japan, swordmaking was a ritual process that resulted in a blade similar in pattern, although not process, to Damascus steel. In some cases, the blade's pattern was reflected in the Mokume-gane, or wood-grain metal, that was found on the hilt and guard of the sword or the sword furniture.
The wood grain pattern is achieved by laminating sheets of differently-colored metals together, reducing their thickness, and then patterning them. In feudal Japan, this was accomplished using a forge. Today, thanks to the efforts of James Binnion and Steve Midgett, and to advances in technology, there are simpler ways of producing Mokume-gane.
I use Binnion's kiln-fired process to fuse differently-colored sheets of metal into a billet. Once fused, the depth of the billet is reduced by rolling. This process also compresses the layers. I pattern the sheet by raising bumps with punches and then filing them away or by drilling into the sheet and then rolling. This produces a topographic map-like pattern in the metal.
It usually takes me eight hours to fuse the billet in the kiln, and another 8 hours to roll and pattern the sheet. After that, the sheet may be formed, sawed, sanded,or soldered into jewelry.
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