Will Precious Metal Clay Revolutionize Jewelry Making?

Nationally known designers assess a startling new material intended to give them more freedom in creating jewelry

Mitsubishi Materials Corp. of Japan has developed a remarkable new material that combines the forming ease of clay with the luster and permanence of precious metal.

The material, called PMC or Precious Metal Clay, was introduced to the U.S. this spring when 15 nationally known jewelry designers gathered at the intentionally isolated Haystack Mountain School on the coast of Maine. The designers experimented with PMC in an environment that fostered playful risk-taking and freewheeling associations. The results point in an interesting direction for the field.

This revolutionary material is enigmatic to those familiar with metal. It is clay, pure and simple. It looks like clay, feels like clay and can be rolled, pinched, squeezed and joined like clay. Unless told, average users would think they were modeling with children’s plastiscene. But the material consists of extremely small particles of metal suspended in an organic binder.

The idea of powder metallurgy is ancient, but this product is distinguished by the fineness of the particles, which have a diameter of less than 20 microns. When fired in the proper atmosphere, these tiny grains fuse together to create a material that is metallurgically identical to its parent material, which could be sterling, fine silver, fine gold, platinum or several colors of 18 karat gold.

The material is produced at Mitsubishi’s high-tech plant in Sanda City, Japan. That plant also produces incredibly thin gold wires used in the production of computer chips.

Simplicity: PMC straddles several millennia in that it employs 21st century technology to create a material that a Neanderthal could work. The tools needed to create innovative forms in PMC are nothing more than your fingers, with perhaps such simple tools as a pointed stick and a sharp rock if you want to get fancy. The firing, which burns away the binder and fuses the metal, might be beyond our primitive ancestors, but is easily within reach of even a modest studio. A small electric kiln like those used for enameling or burnout is all that’s necessary.

As a child of the scientific lab, PMC has been through several years of research and development. Systematic testing has produced exhaustive data, extensive charts and detailed diagrams. From this we can know with authority that the average shrinkage is 28.3% and the average reduction in volume is 63.1%. In laboratory tests, PMC was combined with ceramic clay, fused onto metal matrices and formed over cores of cellulose to create hollow forms. Health and safety testing ensured the material is non-toxic.

The one thing that could never be proven in a lab, however, is the artistic value of the material. Once the scientists were convinced of its technical viability, it was time, as the saying goes, to take PMC on the road.

In this case, the road led to the home of Ronald Pearson, an innovative designer whose elegant forged jewelry has held a respected position in the fine art and commercial world for decades. The Japanese request for assistance in bringing PMC to the U.S. triggered the idea of a hands-on workshop to test the range of this intriguing substance.

Workshop begins: The facilities of the Haystack School in Maine were rented for a week and the group of 15 designers was assembled. In addition to Pearson, the workshop included Jack Prip, John Paul Miller and J. Fred Woell as senior masters. Also attending were Pat Flynn, Patty Daunis-Dunning and Micki Lippe, who each run their own production studio, and Eleanor Moty, Sharon Church, Gene Pijanowski, Kim Cridler, Chris Ramsay, Myra Mimlitsch Gray, John Marshall and myself from the worlds of education and one-of-a-kind work. The first miracle of the week was that a group as diverse in background, aesthetics and approach could be brought together to put this material to the test.

The week started with a videotape tour of the Japanese plant where PMC was developed. It showed huge spotless rooms where technicians in white space suits attended with studious precision to the manufacture and quality control of the clay. We saw computer-linked furnaces with state-of-the-art control systems in which the elaborate testing had been done. We saw highly trained workers peering through microscopes, making dense notations on serious-looking clipboards. Then we shoved our hands in our parkas, trudged through the woods to a plank-floored studio and fired up 10-year-old enameling kilns. This was going to be a test indeed, and if our two Japanese collaborators were concerned, they were courteous enough not to show it.

In its first week in the field, PMC conducted itself admirably. Over the next five days, we proved that creative people working with familiar equipment and a bias against following rules could successfully make interesting objects from metal clay.

We were each given a generous supply of fine silver clay, preferred over sterling clay because it is easier to fire. Our initial reactions ran from pleasure to understandable self-consciousness. As the first batch came out of the kiln, everyone gathered around to watch. The pieces are fired for about two hours, after which they can be quenched in water immediately. What was so recently soft and fragile emerged as a solid metal object, ready to be burnished, colored and polished. It was a miracle that took some getting used to.

Each day the group was treated to further demonstrations in ways to work PMC, and participants were generous in sharing the results of their experimentation. Most people worked from early morning well into the night, only to return eagerly the next day.

Assessing PMC: At the end of our week, a round-table summit meeting was called to assess Precious Metal Clay and its future. Like any material, it has drawbacks. The clay is frustratingly soft in hands most familiar with the delightful resistance of metal; some of us felt all thumbs. This was most pronounced in our early attempts, and everyone managed to improve. The clay can slump during fusing, which creates a softness of form that is not always desired. Its shrinkage, almost to half the original size, was easy enough to compensate for, but it caught us off guard at first.

Because of its porous nature, objects made of PMC are not suitable where high tensile strength is needed, such as findings, chains or settings. On the positive side, this porosity yields objects that are about 80% lighter than the same piece in conventional wire or sheet. The advantages of working larger with less cost and weight are immediately apparent.

In addition, PMC allows a freedom of construction that even the most accomplished goldsmith cannot hope to achieve with conventional materials. Pieces can be cut, textured and assembled literally in minutes once you get the hang of the process. The implications for three-dimensional sketching are obvious; they open the field to a tremendous freedom of forms. Constraints of cost for equipment, time for training, studio space or physical hand strength can be eliminated from the list of elements needed to make jewelry.

The implications of PMC for the field of jewelry are vast and still unclear, which is the underlying excitement of the clay. Nothing like this has existed before, so the path ahead is yet to be mapped. There will always be a role for traditional goldsmithing and the rich traditions and skills associated with it, but we now have one more exciting process to add to our arsenal.

Tim McCreight is professor and department head at the Maine College of Art inPortland. He has taught and exhibited for 20 years and has written six books on metalworking as well as numerous articles and reviews.