Since Steve Midgett is the expert on mokume gane, I turned to his book, Mokume Gane: A Comprehensive Study, to explain a little of the nature of mokume gane and a little of its history. If you want to know more, I recommend reading the book: it’s like taking a class from Steve — another good idea. If anything here isn’t quite right, though, it’s my doing, not Steve’s.

There are different methods to creating mokume gane; Midgett uses diffusion bonding, in which two metals form an alloy at the planes of contact which binds the parent metals together. Diamond wedding rings, platinum and 18K gold. Photo: Ralph Gabriner.

Mokume gane is an ancient Japanese metalsmithing technique that creates beautifully patterned metal. The process involves layering different colored metals, welding them together while maintaining the original colors, then texturing or manipulating the metal in a way that reveals a bit from each of the layers, which in contemporary jewelry may number from about 12 to 25. Creating the patterned metal is an art in itself; it is another art to create beautiful pieces from this crafted metal.

While researching this technique, Steve came across the published works of Hiroko Sato Pijanowski and Eugene Michael Pijanowski. Thanks to their extensive research, we know that Denbei Shoami was the inventor of mokume gane. Shoami worked for a feudal lord in Japan during the 1700’s and was clearly influenced by the sword making he did. This is where he first found that nonferrous laminates could be joined together to create patterns similar to the earlier lacquer and pattern-welded-steel work he did. He adapted the principles of forge-welding to create mokume gane. Mokume gane is a technique that was undoubtedly passed down from master to apprentice and originally was used exclusively for sword making. At some point (precisely when is unclear), Japanese craftsmen began using mokume gane for other decorative objects.

Currently, the most accomplished practitioner of mokume gane in Japan is Norio Tamagawa, a ninth-generation metalsmith and former student of Gyokumei Shindo. Tamagawa practices traditional diffusion techniques, which the Pijanowskis have studied thoroughly.

Armed with their acquired knowledge of diffusion-welded mokume gane, the Pijanowskis came back to America to continue their pioneering work in the field, exploring the traditional technique. In the 1980’s, Steven Kretchmer and Eugene Pijanowski began laminating colored golds — and by doing so, opened a whole new arena for the application of mokume.

Much work has continued from there, with new metal combinations, greater understanding of metallurgy, and technological advancements in the manufacture of mokume such as digital, atmospherically controlled kilns. All these things and more combine to make the 21st century the most exciting time in history to be making mokume.

There are many different approaches to the creation of mokume gane, and while most serious craftsmen working in this medium have their own favorites, they share many similarities. The main differences lie in the way in which the layers of metal are bonded together, which include solder bonding and two kinds of diffusion bonding.

Solder bonding is done by sweat soldering layers of contrasting colored metal together. Solid state diffusion bonding is one option that forms a permanent bond between the metals. It occurs if the proper conditions at a temperature well below the eutectic, or melting, point of the metals involved are reached. The eutectic point of an alloy is what is sometimes observed when you see the “sweating” of metals when bonding mokume gane, or the “flash” of fusion during the process of granulation.

Liquid phase diffusion bonding is known to be the most common bonding process both today and throughout history. In this bond, pieces of differing metals are joined without the use of a lower melting temperature interlayer. Instead of sandwiching a piece of solder material between the layers, the two parent metals, through the process of diffusion, form a third alloy at the planes of contact. This alloy liquefies and fuses the layers together.

There are four main groups of metals used in mokume: pure or alloyed copper, silver, gold, and the platinum. The metals used in creating the mokume are cut into small squares, cleaned, and stacked into a billet.

A billet is a stack of layers of metals of contrasting colors permanently bonded together into a single unit. If using mokume for jewelry puposes, Steve recommends using 16- to 24-gauge sheet and to have no more than 25 layers in the finished stack. The finished height of the forged stack should be equal to the dimension of the rolling mill being used for reducing. The key to a good billet is maintaining the bond between the metals and retaining the defined color boundaries between the layers. This is even more difficult than it sounds.

In creating a billet, you run the risk of underfiring and having the billet delaminate during patterning because of immature welds. You also run the risk of the opposite, overfiring, and going beyond the welding stage to the point where the metals diffuse, or melt together, to form a new homogeneous alloy with little or no definition to the individual layers.

There are compatibility issues with metals, too, which can be overcome by knowing which metals work well together. Steve offers an extensive guide in his book, but suggests experimenting with different metals to create your own personal combinations and palettes of colors.

Once you have created a billet, it needs to be forged and then reduced by about 15 percent of its original size. Next, trim and clean up the edges, forge again, and then roll it through a rolling mill until it is about 1û4-inch thick. Once you have it to the proper thickness, you’re ready to pattern the metal. How you approach patterning depends on what you are going to do with the material. You can make an almost unlimited number of patterns with mokume. Steve prefers to use hand processes like forging, twisting, cutting, and chiseling. Once you have a specific finished piece in mind, whether a spoon, knife, decorative piece, or piece of jewelry, you can determine which method of patterning works for you. With any sheet, you are limited only by the number of layers it contains, their thicknesses, colors, and your expertise at manipulating the laminate. Some of the basic patterning techniques include using punches, gouging, twisting, rolling and elongating the patterns, mokume veneer, double lamination, or using carved or eroded surface treatments.

Once you have patterned your metal and created your piece, you need to bring it to a final finish. The fruits of your labors will be most evident once you have finished this process. There are a few alternatives that can be used to bring out the patterns, grains, and textures of the metal. You can use an acid-etching technique, which will remove certain individual metals from the surface, create texture, and define areas of color. Etching followed by sandblasting will remove tool marks left from carving. As a general rule, highly polished surfaces do not work well with mokume gane. A reflection on the surface of the metal distracts the eye from the patterns in the metal. To cut down on this reflectivity, most artists working with mokume put a matte, or brushed finish, on their pieces using acid, steel wool, Scotch Brite® pad, wire brush, or glass bead blasting (as seen in the finished bracelet project found on page 40). As with all design decisions, the proper finish is a personal one. You can also use patinas to enhance the look of your mokume, but if it’s being used in a piece of high-wear jewelry, this might not be the best idea. —TH

Back to the Story

---

Steve Midgett can be reached at his business, Earthshine, by calling 800-374-6423, or via e-mail through his Web site at www.mokume.com.