What is Metal Clay?
There are many examples and definitions of what metal clay is, how it was developed, differences in types, etc. We have included a few of them below.
Metal clay is a clay-like medium used to make jewelry, beads and small sculpture. It consists of very small particles of precious metals (such as silver, gold or platinum) mixed with an organic binder and water. Metal clay can be shaped just like any soft clay, by hand or using moulds. After drying, it can be fired in a variety of ways including in a kiln, with a handheld gas torch, or on a gas stove. The binder burns away, leaving the pure, sintered metal. Shrinkage of between 8% and 30% occurs (depending on the product used), but this is exploited by artisans to produce very fine detail.
Silver metal clay results in objects containing .999 pure silver - aka fine silver, which is ideal for enameling. Although gold metal clay is much more expensive to use, the color and richness is phenomenal. It can be used to make stunning solid gold objects or used sparingly to make beautiful accents on silver pieces.
Lump metal clay is sold in sealed packets to keep it moist and workable. The silver versions are also available as a softer paste in a pre-filled syringe which can be used to produce extruded forms, in small jars of slip and as paper-like sheets, from which most of the moisture has been removed.
There are two popular brands of this material, Precious Metal Clay (PMC) and Art Clay Silver (ACS). Please note that this article was written before bronze and copper clays were developed.
Precious Metal Clay or PMC was developed in the early 1990s in Japan by metallurgist Dr. A. Morikawa. The material consists of microscopic particles of pure silver or fine gold powder and a water-soluble, non-toxic, organic binder which burns off during firing. Success was first achieved with gold, and later duplicated with silver. The original formula of PMC, now called "Standard", must be fired in a kiln at 900 °C (1,650 °F) and has a shrinkage rate of 30%. Mitsubishi Materials Corporation, a subsidiary of Mitsubishi, later developed two additional versions of silver called "PMC+" which can be fired as low as 810 °C (1,490 °F) for 30 minutes, and "PMC3", which can be fired as low as 599 °C (1,110 °F) for 45 minutes. Both PMC+ and PMC3 have a shrinkage rate of 12-15% and may also be fired with a handheld torch for 4-7 minutes. A 22k gold gilding material called "Aura 22", and lump 22k yellow gold clay (an alloy of fine silver and gold) are also available. PMC also manufactures an 22k gold clay and a platinum clay, but these latter two are only marketed in Japan.
Art Clay Silver or ACS was developed by AIDA Chemical Industries, another Japanese company. Art Clay followed PMC Standard with their Art Clay Original clay (more like PMC+ than PMC Standard), which allows the user to fire with a handheld torch or on a gas hob. Due to subtle differences in the binder and suggested firing times, this clay shrinks less than the PMC versions, approximately 8-10%.
Further developments introduced the Art Clay Slow Dry, a clay with a longer working time. Art Clay 650 and Art Clay 650 Slow Dry soon followed - both clays that can be fired as low as 650 °C (1,202 °F), allowing the user to combine the clay with glass and sterling silver which are affected negatively by the higher temperatures needed to fire the first generation clays.
AIDA also manufacturers Oil Paste, a product only used on fired metal clay or milled fine silver, and Overlay Paste, which is designed for drawing designs on glass and porcelain.
In 2006 AIDA also introduced the Art Clay Gold Paste, a more economical way to work with gold. The paste is painted onto the fired silver clay, then refired in a kiln, or with a torch or gas stove. When fired it bonds with the silver, giving a 22ct gold accent. The same year also saw Art Clay Slow Tarnish introduced, a clay which tarnishes less rapidly than the other metal clays.
Precious Metal Clay, PMC, is an exciting material developed and patented in the 1990s by Mitsubishi Materials of Japan. Microscopic particles of silver are mixed with a moist binder to create a material that has the feel and working properties of modeling clay. Using simple tools, objects are easily given shape, texture, and character. After air-drying, the objects are heated to temperatures approaching the melting point of the metal, where the particles fuse together to make a dense, fully metallic object. Fired PMC work can be polished with a burnisher or in a tumbler, soldered, enameled, and enjoyed like any other silver item. PMC is available in three different versions of silver and in a 22k gold alloy.
There are three versions of PMC, called Original, PMC+, and PMC3. Each has special properties, as summarized here. For further details, download "ABCs of PMC"
Ideal working properties, lowest cost, 28% shrinkage, high firing temp.
Good working properties, denser, 12-15% shrinkage, three firing schedules
Densest material, short working time, 12-15% shrinkage, can be torch fired
How Does it Work?
Powder metallurgy is an ancient field, and is widely used in industry. What makes PMC special is that this technology is now available for small studios and classrooms. By using only pure silver and gold, PMC is able to sinter, or fuse, in a normal atmosphere without external pressures or the use of molds. The ability to produce the tiny flakes of metal, and to mix them uniformly with water and binder bring this revolutionary material to us.
What about Cost?
Because is it a high tech material, PMC costs more than conventional silver wire and sheet. This is balanced by the amazing speed with which forms can be made, and the very low investment in tools. Also, all versions of PMC can be rehydrated before firing, so there is no waste.
Who is using PMC?
Jewelers, certainly, who immediately appreciate the ability to achieve effects that would either be time consuming or impossible through traditional methods. Ceramists and polymer clay artists naturally gravitate to PMC too, as do dollmakers, beadmakers, and artists who work with glass. PMC spans all ages, with advocates as young as grade school and as mature as... well, very mature.
How Do I Get Started?
Some people like to take a class or workshop to learn new skills. Other people are comfortable learning on their own, perhaps using some of the books and videos published recently. Can't wait? You can find tons of information here at Metal Clay Guru.
The above metal clay information was obtained from The PMC Guild
When Art Clay Silver is taken out of the package, it is a slightly moist lump of clay. The clay is composed of 1-20 micron sized silver particles, organic binders, and water . The clay is then molded into its desired generic shape, and dried. Once the clay is completely dry it can then be filed, carved, and sanded; after which it is fired with a gas stovetop, butane torch, or kiln.
During the firing process, the organic binders burn away and the resulting silver particles "sinter", becoming denser and stronger. The burning away of binders and sintering of metal causes the piece to shrink 8-10% in overall size while retaining the original form. Once completely fired, the remaining piece is composed of 99.9% pure silver.
What is the difference between Sterling Silver and Pure Silver?
Sterling Silver is composed of 92.5% silver and 7.5% of one or more other metals. A common misconception is that copper always makes up the remainder, when in reality titanium, platinum, palladium, and a list of other metals are often used. The addition of another metal to the silver creates an alloy. Sterling Silver is stronger than Pure Silver, and as an alloy, it tarnishes more quickly as well. Pure Silver is composed of 99.9% silver and nothing else.
These two slides compare Art Clay Silver, finished with a perfect mirror shine, to a piece of Solid Silver. Magnification 2100 times. Note the similarity and the fine surface of the Art Clay.
Is Art Clay safe to use?
Yes, all but one of Art Clay’s products are non–toxic, and most carry the ACMI "AP" seal.
The manufacturer of Art Clay, Aida Chemical Industries, Co., Ltd. is a member of the Art & Creative Materials Institute. The Art & Creative Materials Institute, Inc. is an international association composed of a diverse and involved membership, and is recognized as the leading authority on art and creative materials. ACMI's members are art and creative materials manufacturers, and currently there are over 210 members.
Since its inception, ACMI’s certification program has certified that products in the program are either non-toxic or appropriately labeled with any cautionary language and safe use instructions. Of the 60,000 art materials in the program, 100% of the children's products and 85% of those meant for the adult artist are certified as non-toxic. This certification program has received the endorsement of experts in the field of toxicology and is one of the finest industry programs in existence. ACMI seeks to create and maintain a positive environment for art and creative materials usage; to promote safety in art and creative materials; and to serve as an information and service resource on art and creative materials.
What do the ACMI Seals mean?
The AP (Approved Product) Seal, with or without Performance Certification, identifies art materials that are safe and that are certified in a toxicological evaluation by a medical expert to contain no materials in sufficient quantities to be toxic or injurious to humans, including children, or to cause acute or chronic health problems. Additionally, products bearing the AP Seal with Performance Certification or the CP Seal are certified to meet specific requirements of material, workmanship, working qualities, and color developed by ACMI and others through recognized standards organizations, such as the American National Standards Institute (ANSI) and the American Society for Testing and Materials (ASTM).
Who makes Art Clay?
Art Clay is manufactured in Japan by Aida Chemical Industries. Aida Chemical Industries is a family owned company that recycles and reclaims metals, including the precious metals gold and silver. In 1991 Aida Research and Development obtained a patent for the manufacturing process for a metal clay, which became Art Clay. The clay, paste and syringe types were introduced to Japan in late 1992. The Aida Planning Department began to develop the books and other accompanying materials and, in April, 1994, Art Clay Silver and Gold were officially introduced into the general public in Japan. Art Clay World, USA is the North American distributor of Art Clay, and you can click here for a list of links to other worldwide distributors.
Aida Chemical Industries is a "green" company. It collects metals which already have been used and reclaims these metals. Such items as computer circuit boards and silver from photographic supplies are processed in tremendous quantities every year. A portion of this harvest becomes Art Clay Silver and Art Clay Gold.
Aida combines these reclaimed metals with non-toxic, organic binders. The result is a product which can be handled safely. Every effort has been made to assure the safety of artists using Art Clay. Even the production processes used to create Art Clay are designed to have minimal effects on the environment.
The above metal clay information was obtained with permission from The Art Clay Society
Welcome to the next step in the evolution of metal clay: BRONZclay™! It provides an incredible artistic range. And, because it's bronze, it's so affordable, it can be used to sculpt large pieces and create specialized tools—it can even be thrown on a potter's wheel to shape bronze hollowware. Available in generous 100- and 200-gram blocks, BRONZclay allows the artist to experiment with how far (and big!) designs can go.
BRONZclay can be pinched, rolled, sculpted and manipulated. In its dried state, it's still highly flexible and easy to carve—an ideal canvas for applying details and finishing touches prior to firing. When fired in a kiln, the binder vaporizes, leaving a solid, pure bronze object that can be sawn, shaped, drilled, sanded, patinaed or soldered using traditional jewelry tools and techniques. This exciting medium offers a new world of possibilities for jewelry makers, artists and sculptors.
The Art of Metallurgy
The metal of choice as far back as 3500BC, bronze delivered more strength and durability than iron and commanded a higher price. Every day, bronze artifacts are unearthed, still in excellent condition, still rich in color, full of history and representing an incredible combination of skill and art.
Growing up, Bill Struve, the inventor of BRONZclay™, thought about being a physicist or maybe a psychiatrist, but he wasn't interested in math or medical school. Instead, he earned a doctorate in classical chemistry and a master's in electrical engineering, working 20 years in each field before embarking on a third career: art, in the form of metallurgy.
His desire to produce a new medium for his wife to use to create strong, durable and wearable jewelry inspired Bill to experiment for countless hours before achieving success with BRONZclay™. As Bill developed BRONZclay, one of his goals was to keep its ingredients safe to use. Another was to keep the tools needed for working with the clay simple: nothing fancy, just the basics, a kiln and the artist's imagination. BRONZclay would be a gift to the artist, a new addition to the tool box.
The Right Formula
BRONZclay™ consists of 11% tin, 89% copper, water and non-toxic binding materials. The binding materials vaporize completely during the kiln-firing process, leaving a solid bronze piece with a density 90% that of cast bronze.
Commercial Bronze vs. BRONZclay™
BRONZclay™ is true bronze (although a bit less dense) and is composed of tin and copper, not the brass form that you see in most commercial bronze.
What is COPPRclay™?
The Right Formula
COPPRclay™ consists of pure copper, water and non-toxic binding materials. The binding materials vaporize completely during the kiln-firing process, leaving a solid copper piece with a density over 95% that of cast copper. And, all copper used to make COPPRclay™ is recycled!
What is PMC Pro™?
PMC Pro™ is like the other forms of PMC only better! It can be rolled, modeled, carved, layered, cut, textured, and assembled like Original PMC, PMC+ and PMC3. It has a longer working time and more green strength. As with bronze and copper clays, use the same tools but wipe them with a cloth when switching between materials. Allow a little longer for PMC Pro™ to dry.
PMC Pro contains 90% silver with the balance being a proprietary alloy. Sterling contains 92.5% silver, balance typically copper.
Click here for more specific details on PMC Pro™.