Mokume Gane: Manufacturing Works of Art Part 2

This is part 2 of an article written by my friend Mark Mann. It was published in 2004 in a magazine that unfortunately no longer exists. Mark has kindly allowed me to post this here.

By Mark B. Mann

Technical Contributions by James Binnion, James Binnion Metal Arts, LLC, Bellingham, WA

Last month, we reviewed methods and techniques used by James Binnion to design and manufacture mokume gane jewelry. In this installment, we review installation methods of the rails and liners on his mokume-gane bands and common service features associated with mokume-gane articles of jewelry.

Rails and Liners

Rails and liners are terms used to describe edge trim pieces and the inside solid flat surface of a single alloy for mokume gane bands. They are optional features on James Binnion’s mokume gane bands and here are some examples of how his products are offered:

This band has no rails or liner and the mokume gane pattern is visible from all views.

There are yellow gold rails on each side of the band and the pattern remains visible on the top and inside ring views. The rails provide a single-color design element on each side, essentially framing the mokume gane pattern.

This band has yellow gold rails and a liner. The pattern is visible from the top view. The liner enhances engraving possibilities on the inside of the band making it easier to read. Occasionally certain individuals may have  a sensitivity to one or more of the metals in a mokume gane laminate and the liner (made of gold or platinum) inhibits direct and constant contact with those alloys and this can alleviate the sensitivity issue.

Installation Techniques for Liners

Caption – This palladium white gold and sterling silver mokume gane band is being prepared for a 14-karat palladium white gold liner. Here it is mounted in a lathe and the cutting tool will create a flat surface inside the band.

The inside edges of the shank are then chamfered. The palladium white gold liner is made to specifications and after precise fitting, it is inserted and mechanically pressed into the band then flared on each edge.

Installation Techniques for Rails

For this palladium white gold and sterling silver mokume gane band, grooves are cut on the sides and 14-karat palladium white gold rails are precisely fit. The rails are wired to each side and the band is prepared for soldering.

Beads of 14-karat white gold easy solder are evenly placed around the seam between the rail and the band. A hot air gun is used to dry the flux and to secure the beads of solder. The ring is placed on a custom stand and soldering is completed.

Mokume Gane Jewelry Service Considerations

Like most jewelry products, mokume gane jewelry may require sizing and alteration to meet customer’s special requests. Here’s a quick guide to handling mokume gane for the retailer:

  1. Sizing – Binnion Metal Arts offers sizing to retailers carrying his products. The ring sizing is accomplished through compression and expansion to fulfill the sizing requirements. Since ring sizing gauges and ring mandrels differ, Binnion provides brass sizing blanks marked with the ring sizes for his customers. They are calibrated to Binnion’s studio mandrels for precise sizing results. By performing the ring sizing through expansion and contraction, the pattern remains consistent around the ring.
  2. Custom Orders – Binnion accepts custom orders for his mokume gane jewelry. He creates and provides CAD (Computer Aided Design) images to his customers for easy viewing of the custom designs.
  3. Finishes – Binnion Metal Arts produces several finishes on their mokume gane jewelry. Jewelers can easily reapply the finishes after wear or they can be returned to Binnion’s studio for refinishing.
  4. Gemstones and Settings – Gemstones and settings can be added by jewelers using standard soldering and setting techniques. Flush setting can be done in the mokume gane as well as soldering for settings.
  5. Display – With daily handling (set up and take down of displays) mokume gane jewelry will need to be periodically cleaned. Binnion provides easy cleaning instructions or offers to clean the products free of charge.

Mokume gane offers a unique product category for retailers. The metal combinations, colors and patterns created in mokume gane jewelry are endless, so it’s virtually impossible to have two items alike. Although wedding sets are designed to be complimentary in color and pattern, each is a singular work of art.

James Binnion has been a jewelry designer and metalsmith for over 20 years. He established James Binnion Metal Arts in 1991 to refine the art of mokume gane. His line includes earrings, pendants and cufflinks in addition to his wedding, engagement and commitment rings. To find out more about mokume gane and James Binnion Metal Arts, visit For questions related to mokume gane, contact James Binnion at For questions related to Binnion’s mokume gane jewelry products, contact Terry Binnion at 360-756-6550 or by e-mail at

Mokume Gane: Manufacturing Works of Art Part 1

This is an article written by my friend Mark Mann. It was published in 2004 in a magazine that unfortunately no longer exists. Mark has kindly allowed me to post this here.

By Mark B. Mann

Technical Contributions by James Binnion, James Binnion Metal Arts, LLC, Bellingham, WA

This mokume gane 9 millimeter wedding band contains 14-karat palladium white and sterling silver. It is a comfort fit wedding band with 18-karat yellow gold millgrain rails and a liner. It was designed and produced by James Binnion of James Binnion Metal Arts, LLC in Bellingham, WA.

Mokume gane translated from Japanese means “wood eye metal”. This rare metal lamination process was developed and used by Japanese craftsmen in the 17th century for the adornment of samurai swords. Today, mokume gane jewelry is growing in popularity and this article (part 1) covers the details related to the manufacturing process. Next month, part 2 will cover other features such as ring liners and rails, settings, servicing and quality issues.

The Layering and Bonding Process

The mokume gane process begins by layering and bonding several sheets of two to four different metal alloys together. The bonding of metals can be done using solder or by fusion bonding. This overview describes a solder-free solid state diffusion bonding method developed and used by James Binnion.

The materials used for this mokume gane manufacturing overview are alternating sheets of 14-karat palladium white gold and sterling silver. The central portion of the featured mokume gane example in photograph #1 is made of the same materials. Each sheet of metal is approximately 1.5 millimeters thick.

Chipp Allard, Binnion’s assistant who studied at the Revere Academy meticulously cleans each sheet by placing them in a holding spring in a plastic bowl. Tiva cleaning solution is added and the bowl then held in the ultrasonic.

Next Allard individually sands the sheets using a three step abrasive procedure. After the abrasive procedure is completed, the sheets are rinsed and dried by blowing them off with nitrogen. They are then placed in a vacuum chamber to pull off any remaining water vapor.

Binnion places the cleaned sheets (indicated by the arrow) in a torque plate in preparation for compression. The torque plate is positioned in a hydraulic press as shown and the sheets are mechanically compressed. Binnion states that compression creates “intimate contact” between layers.

The torque plates with the compressed metal are placed into a container and then covered with hot powdered charcoal. The container is then capped and lowered into the kiln for diffusion bonding. The time and temperature for bonding depends upon the alloys. After the bonding is complete, the torque plates and metals are allowed to cool. The newly bonded metal sheets, now referred to as a billet is removed from the torque plates.

Next Binnion reduces the thickness of the billet by 30 to 60 per cent. This step also increases the integrity of the bond. To do this, he will heat the billet to annealing temperatures in a small furnace, then place it in a heavy drop hammer and quickly hit the foot pedal. The hammer drops and compresses the billet. He repeats this process several times to obtain the required reduction.

The billet is then cut into bars then twisted and rolled round. The rounded billet is forged in the hydraulic press in preparation for the jewelry piece, in this case, a comfort fit band

Creating the Pattern

The next step is patterning – which is the creation of the pattern of bonded metals around the band. In this example, the yellow, red and palladium white gold pattern resembles wood grain. Patterns are accomplished by repeating a multiple step process of high speed carving, de-burring, forging and shaping. This is where Binnion’s true artistry comes into play in creating his unique mokume gane jewelry. Notice the pattern is visible from the top and inside views of the band. The rails are made of 18 karat yellow gold and soldered to each side of the band after the ring is formed.

For the first step in creating the mokume gane pattern, Binnion uses a high speed 1/2 horse power turbine air tool running at 45,000 rpm with a carbide bit to carve patterning indentations into the billet.

After carving and deburring the billet, Binnion inserts it into a custom made ring forming dye and places it in a hydraulic press to be forged. The forging process flattens the carved billet, ultimately creating the unique pattern. This photo shows the billet after several repetitions of carving, de-burring and forging.

The billet began measuring 8.25 millimeters in width and needs to be 6.5 millimeters when completed. Final shaping and forming will be done with custom made dies and a rolling mill.

Allard then takes the ring blank and cuts it to length to fill the order. He uses an adapted vice to hold the billet for sawing.

The ring blank billet is placed into a tube furnace for annealing. Argon flows into the chamber creating an inert atmosphere and limiting oxidation. When completed, Binnion pulls the blank out of the furnace and it drops into water.

To form the ring, a bending device with custom made forming jigs is used. The Delrin jigs eliminate excessive tool marks

Allard shapes the ring and adjusts the alignment preparing it for soldering.

Soldering is done at a custom soldering station with the hardest possible solder allowing leeway in performing future alterations on the ring. The ring is firecoated with a mixture of boric acid and denatured alcohol. Because there are different metals in the ring that expand and contract at different rates, its necessary to “confine” the ring during the heating process with the custom made holding device.

All that’s left is the finishing. Binnion uses a variety of finishes on his pieces. His favorite is a matt finish to highlight the contrasting metal colors. He often uses an etched finish on pieces containing silver. Here are some examples of his designs, patterns and finishes.

This pattern is referred to as a “tight star” and has a matt finish. The metals are 18-karat yellow gold, 14-karat palladium white gold and 14-karat red gold. The ring has a platinum liner and rails.

This ring is a 6 millimeter wide comfort fit band with an etched finish. It has a tight star pattern and contains 14-karat palladium white gold, 14-karat red gold and sterling silver.

This ring is 6 millimeters wide with a tight wood grain pattern. It contains 18-karat yellow gold, 14-karat palladium white gold and sterling silver. The center stone is a mandarin garnet and the side stones are green diamonds and they are set in 18-karat yellow gold bezels.

Next month, part 2 will feature Binnion’s methods for the installation of liners and rails on his designs, servicing and aspects of quality for mokume gane jewelry.

James Binnion has been a jewelry designer and metalsmith for over 20 years. He established James Binnion Metal Arts in 1991 to refine the art of mokume-gane. His line includes earrings, pendants and cufflinks in addition to his wedding, engagement and commitment rings. To find out more about mokume gane and James Binnion Metal Arts, visit For questions related to mokume gane, contact James Binnion at For questions related to Binnion’s mokume gane jewelry products, contact Terry Binnion at 360-756-6550 or by e-mail at

Photographs by Mark B. Mann

© 2004  Visual Communications, Inc.

Shibuichi and Sterling

A new metal combination for our rings.

Shibuichi / Sterling Wedding Rings

Shibuichi & Continuum™ Sterling Silver
We are very excited to offer our newest metal combination, which is visually striking and durable; also the most affordable of our precious metal combinations. Given the high cost of gold, palladium and platinum it has been difficult to offer a high quality, lower cost mokume gane ring using precious metal alloys in the laminate. Our Damascus steel and blackened stainless steel have a lower cost than our gold or palladium mokume rings, however those metals don’t necessarily appeal to people who want a precious metal ring. By combining Continuum™ sterling silver and shibuichi we are able to offer a ring with beauty and high durability at a much lower cost than rings with other precious metal alloys.

What is shibuichi?

Shibuichi is a traditional Japanese copper / silver alloy. The name translates into English as “one quarter”. Shibuichi was often used to decorate a samurai sword’s handle and scabbard. Shibuichi has a nominal composition of 75% copper and 25% silver but can range from 5% – 60% silver. At 75% copper / 25% silver it has a pale copper color. In traditional Japanese work it was typically patinated to various shades of grey. I chose to use the 75% copper 25% silver alloy as it gives the resistance to corrosion and strength properties I was looking for.

What Is ContinuumTM Sterling Silver?

ContinuumTM sterling silver is a patented alloy from the jewelry supplier Stuller. It was developed to produce a sterling silver with improved hardness and tarnish resistance. Its use in our mokume gane in combination with shibuichi allows us to offer a beautiful, tough and long-lasting ring.

Color: While shibuichi is initially pale copper in color the alloy quickly will turn to a medium grey color with some copper tone highlights in daily wear. We will normally apply a treatment that colors it to grey before shipping. As it is worn it will develop a unique patina of grey with some coppery highlights.

Corrosion resistance: Shibuichi with its silver content is much more resistant to corrosion than I had initially thought. I conducted extensive tests similar to those I did on copper silver rings to see if this metal combination would be satisfactory for daily wear. This metal combination passed all of my tests. I feel confident in offering this metal combination as part of our precious metals mokume line.

Options: We can use this metal combination in all our ring styles and jewelry. Prices will be significantly lower than any of our other metal combinations that include gold, palladium or platinum.

In order to have a high contrast in the pattern, this metal combination will only be offered as etched.

To see more information and images got to the Shibuichi catalog page

Who Wants To Come To Japan?

In late October 2017 I received an email from a woman with a TV production company in California; she wanted to know if I would be interested in trying out to be on a Japanese television show, which best translates to “Who wants to come to Japan”. My first reaction was to question if this was some kind of scam! After watching the YouTube links she had sent and with a bit of guesswork (I don’t speak Japanese) my impression was that the premise of the show was to find people around the world who had a strong interest in practicing some form of Japanese craft. The show’s definition of the term craft is a bit broad; they featured people interested in a wide variety of Japanese cultural activities ranging from traditional handcrafts to cooking to martial arts.   I responded that I would be interested in becoming a contestant. They asked me to answer a fairly long list of questions and provide a one-minute video selfie introducing myself.  A few weeks later the production company contacted me asking about a couple of dates for a camera crew to come here to shoot me in my studio to show both my work in mokume gane and studio practice.  They also wanted to film in my home with my wife Terry and with my adult daughter Joya with the focus being a meal prepared by us and shared with the director on camera. We agreed to a time, which needed to be rescheduled to a later date due to some transportation difficulties.

We welcomed the director and a cameraman from Japan along with an interpreter from LA at 10 AM on Christmas morning 2017.  Unfortunately due to the date change for their arrival, Joya was not able to be with us during the filming. We started with a couple of takes of us meeting the director as she came to our front door and we introduced ourselves. The production company had given us a proposed schedule for the Christmas day with the possibility of some additional shooting the next day. Since they wanted to see us prepare a meal I had told them I would prepare a BBQ Texas style brisket (one of my specialties) for the evening meal.  It is best smoked low and slow so I was up early to get it on the smoker for a scheduled 5 PM meal; it was smoking away when they arrived.

After capturing meeting at the door, introductions were made inside and we spent time with our 3 guests commenting on and shooting many of the Japanese items that are in our home. We have always enjoyed the Japanese decorative arts and have collected a few items that are on display.  They also filmed Terry wearing the some of the jewelry I have made her.  At one point while they are filming and talking with us, Terry and I noticed that the cameraman was focusing on our holding hands and a comment was made that we were a cute couple.; this will become important later on.

We discussed mokume gane and when I became interested in it (high school) and how I learned to make it (reading/self-taught). I brought out the books and papers that had been my starting point with mokume gane. I explained that Hiroko and Gene Pijanowski had brought the technique from Japan to the US metalsmithing community in the 1970s and that their and their students’ writings were what had given me the information to begin my exploration with mokume gane. The director asked if I was chosen to go to Japan who would I like to meet: I told her Norio Tamagawa would be my ideal choice.  He taught Hiroko how to make mokume gane and is a Living National Treasure in Japan for his work in mokume gane.

After the initial shooting in the house we went to the studio and I began demonstrating the process of making a mokume gane billet. I had been asked to have some material prepared in advance so that we would not have to go through the whole process sequentially from start to finish.  However, even though we did jump around a bit they filmed the whole sequence of preparing, firing, forging, patterning and finally making a ring from the billet. It was a long day in the studio. This will not be surprising to those who know me: when it comes to mokume my ADD switches into the hyper focused mode and I can easily lose all track of time and they were happy to keep filming. After finally finishing the whole process it was time to go tend to dinner.


Since I like to smoke brisket around 10 hours and we had discussed having dinner around 5pm, I was up very early that morning to put the brisket on the smoker.  I had planed to pull it off the smoker around 4pm, but we did not return from the studio until close to 8PM so it was getting a bit dried out. We prepared some pinto beans, cornbread and an apple-bell pepper salad to accompany it. The crew filmed the preparation and then shot a lot of close up images of the finished food. It really was beginning to make me wonder if I had somehow ended up on a food show! Eventually the director, Terry and I sat down and ate the meal while the cameraman and interpreter filmed and provided translation. Once the director was satisfied she had what she needed everyone was able to relax and eat.  This was their first taste of smoked Texas brisket. Prior to their returning to their hotel plans for the next day were discussed.  They wanted to film downtown Bellingham in the morning but it was going to be pretty quiet since it was the day after Christmas; we suggested the Fairhaven area with its many shops and views of the Bay instead.

The next morning they spent quite a while with Terry and I sitting on our couch on camera while the director interviewed us. She wanted to know more about mokume gane and my background; a lot of it was repeating things briefly covered the day before. They are very observant.  Terry was only answering questions when asked, but at one point the director said something to the interpreter who smiled and told Terry she could jump in and add comments to Jim’s comments if she wanted to…because they knew she usually would!  Again we noticed the cameraman taking some shots with our arms entwined while we talked. We were beginning to wonder if public displays of affection were somehow unusual in Japan.  We returned to the studio to capture a few more things the director wanted to focus on.

They had asked Terry if she would mind if it was only myself they took to Japan.  Since 2018 is our 20thwedding anniversary year we had hoped to go to Japan in the fall; we suggested our paying for Terry to come out at the end of my trip to Japan for time on our own.  The last thing they needed from us was to capture a signature piece for the show: all the participants are filmed moving in towards the camera and loudly saying “Nihon ni ikitai” while raising their arms up in the air; this means “I want to go to Japan”. This was probably the funniest part of the experience. We were outside and the director had both Terry and I run at the camera while holding hands saying loudly “Nihon ni ikitai” (and then extending our arms out to the camera) and it took several takes to fully understand what was needed and get it right. We finally did it right and after the director said cut the cameraman pointed up in the air and we could hear the airplane that had chosen that moment to fly overhead so we had to do it again so that that would not be in the audio.  They also had me do it myself as they explained they might sponsor both of us or only me so they needed both versions.

We said our good byes and were told that after they got back to Japan and the production people had looked at the video someone would be in contact. So the wait began.  There was no guarantee I would be chosen.  They had filmed someone else in the US prior to filming here so we did not know if we would be picked or someone else would.

The story continues in my next post…

Love to Research, Hate to Write

DSC_0027 copyI don’t (really don’t) like writing, and I like a hard deadline to get things done. But I love doing research as much as most people love going on vacation. Maybe more. Much of my research has led to improvements in my manufacturing and design processes, so research always has always had an economic benefit for me. But I have to admit, most of the time I don’t start doing research for economic benefit—I start it because I am curious.

If you are in the jewelry industry, you already know about the Santa Fe Symposium. If you are not in the jewelry industry, then you should know that the Santa Fe Symposium is an annual gathering of curious minds in the jewelry industry, all interested in improving the way we do things. The Symposium was started by a guy named Eddie Bell (Rio Grande Jewelry Supply), who strongly believed that the people working in metallurgy, jewelry design and jewelry production should share their knowledge for the betterment of all. It’s an impressive event; four days of serious presentations that have led to over 30 years of improvements in jewelry manufacturing production techniques, worker safety, environmental benefits, and product innovation.

So, back to the part about how I hate writing but I love research. For the past 14 years I have volunteered to write and present papers for Santa Fe Symposium ten times (have I mentioned that I also hate making presentations?). Why? Because A) I love research, and B) there’s a deadline. I have produced research papers on everything from the history of Mokume-gane to the bonding characteristics of difficult metals.

Today I am staring at a studio with 40 models of the same ring. I am going to test 40 different production approaches in an attempt to explain why the resins used in 3D model-making don’t behave consistently during manufacturing, and I’m looking for insights regarding how to improve results. If you’re a jeweler, you’re likely interested in anything that can be done to improve your production results. If you’re a jewelry consumer, then the way this affects you is to improve the quality of your jewelry and to keep your jewelry prices reasonable.

The testing of all these molds will be great fun for me. I’ve already designed the 40 different tests I am going to do, and now I just need to put in the time doing the tests and document each step and result. Then I have to write the paper, so . . . good thing there’s a deadline.

Interested in learning about my findings? Join me at the Santa Fe Symposium, May 15-18 in beautiful Albuquerque, New Mexico! Here’s a registration link to get you started:

Papayas, Tacos, Metal and Creativity

Cooking TacosDo you think a person’s essential personality shows up in the way they cook? In my case, it might.

I’m the primary cook at our house, so I’ve had some time to think about this. Some people follow recipes to the letter, other people don’t use recipes at all. I use recipes as a starting point, a suggestion that can set me off in any number of directions (and sometimes one recipe can send me in many different directions over time). Continue reading “Papayas, Tacos, Metal and Creativity”

A Bit of Heat, A Bit of Pressure, and a Lot of Skill

Making mokume-gane is a pretty complex process, and those of us who do it become immersed in the physical science of how metals behave (or don’t) when heated, punched, carved, cut, and handled in dozens of ways. In fact, I write scientific papers about making mokume-gane about once a year, and my ability to get too technical is pretty well known. In this blog though, I’d like to share with you different aspects of making mokume-gane, but in less technical terms for those who don’t wear pocket protectors and stare at phase diagrams for fun! Today, let’s talk about what a billet is (and no, I don’t mean a place where soldiers lodge). Continue reading “A Bit of Heat, A Bit of Pressure, and a Lot of Skill”

A Private Showing at the Museum of Fine Arts Boston

Image Credit: The Sword Site Online Sword Museum
Image Credit: The Sword Site Online Sword Museum

When you build your business around an ancient, not-very-well-documented art form as I have, any opportunity to see the work of past masters is pretty exciting.  It was 2002, and I was scheduled be in Massachusetts to teach a class at MetalWerx School for Jewelry. I contacted the Museum of Fine Arts Boston to see if it would be possible to see a mokume-gane masterpiece in their collection. Continue reading “A Private Showing at the Museum of Fine Arts Boston”

Why you don’t want a copper and silver mokume gane ring.

AgCuDay10_1 Corroded copper and silver ring with the copper almost completely gone

No, I will not make you a copper & silver mokume ring.

It is not because I don’t like the color contrast. I love the color contrast that copper alloys have with silver in mokume gane. The original Japanese  work in mokume gane was almost all done in copper alloys and copper alloys with silver. Those strong color contrasts are one of the things that originally attracted me to mokume gane.

It is not because it is cheaper than the precious metals that are in most of my ringsThe rings I make are labor intensive. The mokume process is very time consuming and exacting. We hand make every ring for a customer; we do not mass-produce or machine-produce these rings. I and my studio assistant make every piece of mokume gane. We cut, clean, stack fire and forge the mokume billet from the individual sheets of metal. Most of the metals I alloy, cast, forge and roll into sheet myself to get the color and working properties I want for my mokume gane billets. Almost all the rings we make are intended to be wedding or engagement rings. They hold great significance for my customers as the visible symbol of their love and commitment for one another. Because of this I strive to make the best mokume gane rings we can possibly produce for each and every person who has entrusted us with the job of making his or her ring. So even if we were to make a copper and silver mokume gane ring it would not be inexpensive due to the time and care we put into each and every one of the mokume rings we make.

The reason I will not make you a silver and copper mokume gane ring is that they self-destruct.  Copper is a base metal as opposed to being a noble metal. In chemistry, noble metals are those that are resistant to corrosion and oxidation in moist air. The noble metals are gold, platinum, palladium, silver, iridium, osmium, rhodium, and ruthenium.  In and of itself copper being a base metal is not the problem. By itself when worn on the skin copper will corrode and turn your skin green; this is a nuisance but many people are ok with these phenomena and wear copper bracelets or rings. The problem comes from a physical property of metals: galvanic corrosion.

A galvanic cell is what is created when you connect two different metals in the presence of an electrolyte. It makes an electrochemical cell otherwise known as a battery and electrical current will be produced. So what has this got to do with a copper and silver ring?  There is a battery formed by the copper and silver when the ring gets wet; salts on the skin, lotions and soaps or other substances in the water create an electrolyte. This current will flow from the more negative metal to the more positive one. When this happens,  galvanic corrosion causes the more positive metal to dissolve or corrode into the electrolyte and the more negative metal is inhibited from corroding. Copper is the more positive metal in the copper silver pair and it begins to dissolve every time it gets wet. The speed with which this happens is controlled by many variables and it is impossible to predict how fast the process will be for any individual. However it will happen! Any ring made from a base metal (such as copper) in contact with a noble metal (such as silver) will corrode. Rings made from noble metal pairs (such as gold and silver) will still form galvanic cells but their resistance to corrosion (nobility) keeps them from being dissolved into the electrolyte.

When I first started making mokume gane rings I did not understand this. I made rings with gold and shakudo and with silver and shakudo. Shakudo is a traditional Japanese decorative copper alloy that is about 95% copper with the balance being gold. It takes on a dark black color that is very striking when laminated to high karat gold metals.  Another artist told me about galvanic corrosion and I began to research it. After learning more about it I decided self-destructing rings were probably not a good idea so I quit making them. But over the years I have had the occasion to see rings that I had made where this corrosion was very obvious.

Top photo after about 18 months of wear. Bottom photo the same ring when it was brand new. Top photo after about 18 months of wear. Bottom photo the same ring when it was brand new.

The experimental ring.

To illustrate the problem of galvanic corrosion I decided to make a copper sterling silver ring and perform an experiment with it.   I published my experiment on another blog on a jewelry-making site. Since we often get requests for copper silver rings I thought I would share that post here as well.

Since this was first posted several people have somehow assumed this is a problem with all mokume gane.  It is not! The corrosion will occur only if one or more of the metals in the ring are a base metal and two metals are connected in a wet environment. This corrosion will not happen with rings made entirely of precious metals. Rings worn daily are the jewelry items that will typically be affected due to the fairly constant wetting of ones hands.

This test is an accelerated aging test so you will not see this level of effect with normal wear in this short a time, but it will occur. How quickly will vary widely with the individual and their environment. I have seen this level of corrosion over the period of a couple of years on some individual’s rings that had copper or shakudo elements in contact with gold.  Two metals joined together in the presence of an electrolyte create an electrolytic cell that is in essence a battery. In a ring the electrolyte is provided by the water you constantly expose your hands to through washing, sweat, swimming etc. One of the metals will be more electrically positive called anodic and one will be more electrically negative called cathodic. The difference between these poles is measured in volts. When exposed to the electrolyte the anode will dissolve and supply ions to the electrolyte. The higher the voltage the greater the activity and the faster the anode will dissolve.  The higher a metal is on a galvanic series chart the more noble it is and the more cathodic or negative it is. The precious metals are at the top of the chart which why you will occasionally hear them referred to as noble metals.

So what all does this mean? If you combine silver (noble metal) and copper (base metal) as in the ring above you will have an electrolytic cell where the silver is the cathode and the copper is the anode; the copper/anode will corrode.

No matter how the two metals are joined (bonded as in mokume, soldered, riveted), it will always create an electrolytic cell. When copper is placed in contact with an electrolyte the copper will give off ions to the electrolyte and dissolve. How quickly is the next question, which is what I wanted to know. When copper is placed in contact with an electrolyte the copper will give off ions to the electrolyte and dissolve. I wanted to know how quickly this happens so I set up a test to find out.

Believe it or not there are defined standards for test solutions to simulate human sweat for testing properties such as colorfastness of fabric dyes; the EU uses another one to test for nickel release in jewelry items. I looked up several of them and picked one that seemed to be both easy to make and not too concentrated. I chose 7.5g/l NaCl, 1.2g/l KCl, 1g/l urea, 1ml/l lactic acid with a pH of 4.57. I placed this mixture into a beaker at room temperature and suspended the ring in it with nylon fishing line. I thought I would check on it once a week or so but I took a peek at day one to see if anything had happened. Much to my surprise etching had become visible in only 24 hours.

Silver Copper Day0 Day 0: The experimental ring, highly polished, non-etched in sterling silver and copper before beginning the test.
The copper showed definite signs of etching in just 24 hours The copper showed definite signs of etching in just 24 hours
AgCuDay1Close1 Day 1: The crystal structure of the copper is clearly visible where the sweat solution has begun to etch it.
AgCuDay3 Day 3: So I decided to check back in another 2 days. At this point the etching was quite pronounced.
AgCuDay7 Day 7: The ring was severely etched.
Day 7 close up: In fact in some places the copper had been totally eaten away. Day 7 close up: In fact in some places the copper had been totally eaten away.
AgCuDay10_1 Day 10: The end of the test.
At this point the copper rich areas of the sterling were beginning to be affected by the solution and in many places the copper was totally gone. In another few days the ring would have fallen apart. Day 10 close up: At this point the copper rich areas of the sterling were beginning to be affected by the solution and in many places the copper was totally gone. In another few days the ring would have fallen apart. Quite beautiful in a very distressed way.

What should you take away from this?  Copper-silver rings will corrode/etch over time….it may take months or years but it will happen.  It often starts subtly so it may be a long time before you notice.  However if you want a ring that will last a lifetime buy a ring made from a combination of noble metals (platinum, gold, palladium and/or silver).

If you would like to see some of the rings we make that will not have any issue with galvanic corrosion take a look here

Thanks for reading,