Its twists recall the gnarls of richly burled wood; its waves, the surging seas that lash at Japan’s shores.
So much more than mere chemistry, mokume gane is a fusion of two or more metals that, when manipulated by skilled hands, creates intriguing patterned stock coveted by jewelry designers and collectors alike.
The technique was developed in Japan some 400 years ago to adorn sword furniture—such as the tsuba or scabbard—of Samurai weapons. Since most people in feudal Japan didn’t wear jewelry as we think of it today, swords were a primary means of decorative expression. Mokume gane was originally fabricated to replicate what other artisans were already doing to adorn the warrior class' swords with lacquer.
Both mokume gane and lacquer were meant to evoke patterns found in nature. In fact, the term mokume gane literally means "wood-grain metal."
As the process was being re-discovered in the 1970s, many pioneers believed the technique's future lay in hollowware. To their surprise, metalsmiths instead began incorporating mokume into jewelry, for everything from bracelets to wedding rings. Today, Americans such as Phillip Baldwin, founder of Shining Wave Metals, are taking the craft to new heights.
Baldwin joins two or more metals—these days much of his work is with Argentium® Silver/copper (AS/Cu)–by allowing their crystal boundaries to grow into each other until they are about 50% bonded. His technique takes into account the metals' unique properties.
"One of the charms of Argentium® is that heat-treating the metals changes the ball game," Baldwin says. "You can take a thin piece of annealed material and make things that are light and strong—perfect for jewelry, especially rings. And using less material is especially important today with the rising cost of metals."
Baldwin established Shining Wave in 1983 with a mission to produce exotic metals on a commercial basis. He quickly found that making mokume gane on a production basis was very different from making it for studio use. He wanted to offer enough different types of mokume to fill a variety of needs, from blank stock to pre-patterned sheet, all in several different alloy combinations. It was a tall order, so his studio developed a hybrid process that relies on solid-state fusing. "It not only sped up the process, it made the results more certain," he adds. "Most of the metals with which I work are hot-brittle, so I have to go below that hot-brittle point," he explains. "After laying a series of layers of sheet, as many as 27 or more for a single billet or rod, I hot forge it to about half its original thickness." Dull edges are trimmed off, and the resulting mokume is ready for manipulation to create the pattern.
What happens from here is all up to the imagination of the designer, the limitlessness of which was compelling to Baldwin, a metalsmith since the age of 14. "The endless possibility was what got me into working with it at a young age," he notes. "I had a fascination with the techniques, wondering what could be done with other combinations of materials."
Sheet patterns may be formed by incising (cutting hollows into sheet and flattening), repoussé, or by punching. Incised patterns tend to produce designs that look like a topographical map, but Baldwin is especially fascinated by twist patterns.
Rod is almost always twisted, producing patterns that look like rope or snakeskin. Rods may be twisted to a pitch of at least 60 degrees to produce a tight pattern, usually requiring two annealing cycles for 1/4-inch rod. Even with the most abusive twist of all, a 270-degree reverse twist, he enjoys the superb working properties of the material.
"I've never observed any layer separation at all—which I believe is solid testimony to the strength of the bond resulting from these ancient techniques," he notes, "and the malleability of the material is better than sterling."
He added that the temperatures used are important as they avoid firescaling, "because scraping firescale is pure hell."" Also important, he hasn’t noticed surface degradation.
"Argentium® doesn't work harden as quickly as sterling silver or have its memory, so you can push it farther," Baldwin says. "In fact, I haven’t found a minus yet, and the real plus is the unique elements of color and pattern."
Despite the rich patterns created by manipulating the original stock, it is only after the final finish that mokume gane becomes the vivid material that captures designers' imaginations. A fairly bland surface with little visible pattern can be transformed to a strong visual element through either etching or patination. In fact, the duller the original material, the better, as somewhat matte surfaces show pattern better than highly polished ones.
Etching selectively removes one metal by chemical action leaving the un-etched portion high and it gives the pattern texture. Patina changes the color of the metal. Selective oxidation can provide preferential darkening to one of the component metals and increase contrast. Copper and copper alloys, when combined with precious metals, give the strongest possible contrast because of the ability to both etch and patina the copper.
Even with all the experience and thought that goes into developing each of Shining Wave’s stock patterns, Baldwin admits he has no idea how he comes up with their names.
"Civitas is 'city' in Latin, and I think the pattern looks like a city plan, so there you go," he laughs. "And Cusco got its name because I think it looks like Incan stone work."