Metal Clay - A World of New Design Options

Metal clay is an extraordinary material that opens a world of new design options, allowing for jewelers, designers and even amateurs to create nearly any design they can imagine in precious metal!

Metal clay is made of fine precious metal particles (silver or gold), organic binder and water. When fired to the correct temperature, the water and binders burn away, and the remaining metal particles fuse ("sinter") together. What remains is .999 silver (or "fine silver," vs. sterling silver which is only .925 silver) or 22K gold.  It can be manipulated similarly to polymer clay (using many of the same tools), but the result is precious metal. It can be shaped by hand, pressed into molds, cut, extruded, rolled, etc. When fired, it is metal, and can be manipulated like other forms of silver or gold, e.g., filed, sanded, stamped or embellished with patinas like Liver of Sulfur.

Two Major Brands

The two major brands of metal clay are Precious Metal Clay (AKA PMC), manufactured by Mitsubishi Materials Corporation of Japan, and Art Clay from Aida Chemical Industries Ltd.  The two are remarkably similar, and the end products are identical: .999 silver or 22K gold.

Four Main Types

Both PMC and Art Clay are manufactured in four different types:

Lump Clay

Unless otherwise specified, when people refer to "metal clay" they mean the lump form of the clay. This is similar in consistency to polymer clay. Unlike polymer clay, however, it is ready to use right from the package and needs no kneading to soften it.

Paste Type

"Paste type" metal clay is lump clay thinned with water to a thick, smooth, creamy consistency that can be painted on with a paintbrush. Its most important uses are 1) attaching two pieces of unfired clay together and 2) painting layers of clay over objects, generally ones that will burn away during the firing process (such as cork clay, leaves, twigs, or cereal puffs).  While you can make your own paste from lump clay and water, it is almost never as smooth and creamy as the ready-made paste.

Syringe Type

"Syringe type" is lump clay that has been thinned out enough to be able to extrude. It is not as thin as paste type. It comes already packed in its own non-refillable syringe. Syringe clay can be used to create bezels around certain gemstones that can be safely fired with the clay, to create decorations, or to create lacy beads over a foundation that burns away during firing. When working with syringe clay, it's important to keep the tip submerged in a small cup of water so that the clay at the opening doesn't dry out and clog the tip.

Paper Type

"Paper type" clay can be folded to create fine silver origami, cut with a knife or paper punches to create embellishments, or wrapped around a lump clay base to form a bezel for cabochons that must be set after the clay has been fired. It feels a little like vinyl, but it's delicate and cannot be repaired if torn or damaged. Art Clay paper type is about twice as thick as PMC paper type.

In addition to these four main types, there are also other specialty metal clay products, such as Art Clay Silver Oil Paste, an oil-based silver clay thick paste that adheres pieces of fired metal clay together (and must be re-fired), Accent Gold for Silver (AGS) and Aura 22, both gold clay "paints" that can be painted on freshly-fired silver clay (or fine silver) and re-fired to result in 22K gold accents.

Different Formulations

Even within the four basic types of metal clay, there are different formulations with slightly different characteristics. For example, PMC comes in Original, PMC+ and PMC3 formulations. Original PMC shrinks the most (about 28%), while PMC+ and PMC3 both shrink about 12%. Art Clay Silver comes in a Slow Dry formulation that has a longer working time than the regular formula, a Low Fire formulation that can be fired at a lower temperature than standard Art Clay Silver, and a slow-drying, low-fire formulation that has both characteristics.

You can use these different characteristics to advantage when designing your pieces. For example, if you want to make a matching pin and earrings, you can make all three pieces identical in their unfired state, but make the two earring pieces out of a higher shrinkage clay and the pin out of a lower shrinkage clay (e.g., earrings from PMC3 and the pin from Original PMC).

Basic Tools and Supplies

Metal clay is fairly expensive, but fortunately it's possible to get started with a minimum of tools and other supplies. You can start with as little as:

• A heavy plastic report cover, used as a work surface to roll the clay on and keep it semi-covered while working with it
• Olive oil to lightly grease your hands, your roller, your tools and your work surface
• Plastic wrap to keep your clay covered as much as possible while working on it
• A 6" piece of PVC pipe to use as a "rolling pin"
• A deck of vinyl-coated playing cards to use as spacers so that you can roll lump clay to an even thickness
• A butane kitchen torch 
• A soldering pad or block 
• Any sort of cutting tool you wish, from a craft knife to tissue blades to aspic cutters
• Inexpensive paintbrushes 
• Water (preferably distilled)
• Various grits of wet/dry sandpaper, from medium to superfine
• Salon boards (large nail files) in multiple grits, from coarse to fine
• Empty film canisters (for mixing and storing slip)
• A palette knife (for mixing and scraping slip)

You can use found objects to impress interesting textures. Try the corrugated sides of a toothpaste cap, a plastic ballpoint pen cap, toothpicks, silverware handles, pieces of fabric or lace.

You can go a long way with metal clay without buying any fancy tools or supplies. But once you start working with metal clay, you'll probably want to expand your toolkit to give you more options. Some of the first things you may want to add include needle files, a needle tool (you can use a sewing needle with the blunt end glued into a piece of cork or baked into a polymer clay handle), Liver of Sulfur (patina), carving tools, flexible non-stick baking sheets/liners (a great work surface), fine automotive grit wet/dry sandpapers (400-2000 grit), superfine grit polishing pads and polishing papers, a dehydrator to speed the drying of your clay, and a kiln for firing it. (There are also other firing methods, such as the Speed Fire Cone and the Hot Pot system, but they have significant limitations if you're going to be firing a lot of metal clay.)

Learning to Work in Metal Clay

Before you start to experiment with an expensive material like metal clay, you'll want to get some detailed instructions to guide you.

Books

Metal clay books I recommend include Sherri Haab's "The Art of Metal Clay," CeCe Wire's "Creative Metal Clay Jewelry," Jackie Truty's "Art Clay Silver and Gold," and Tim McCreight's book "Working with Precious Metal Clay," among others.

Videos/DVDs

Videos and DVDs I strongly recommend include Hattie Sanderson's DVDs, Linda Bernstein's video series, and the "Push Play for PMC" DVD by Celie Fago and Tim McCreight.

Classes and Certification Courses

The best way to learn is to take a class. You may find one at a local high school, college, or adult education program, or you can find local teachers through the two main industry organizations, the PMC Guild and Art Clay World USA, both of which are fantastic resources. Once you're comfortable with the basics, you may want to take a certification course. There are separate Art Clay and PMC certification courses, and also crossover courses for people who have been certified for one brand and want to become certified for both.

Basic Guidelines

Some things to keep in mind when working with metal clay:

• Plan ahead and work fast! Metal clay dries out very quickly. If you're used to working with polymer clay, you'll need to adjust your working style and pace. Think through (and maybe sketch out) your design before you begin. Make sure you have all your tools and supplies ready to go before you open your metal clay packages.
• Keep your clay covered while you work. Try to keep as much of your project covered with plastic wrap as possible to slow down the drying process while you're still working. You may need to mist your clay with water periodically while you work to keep it from drying out prematurely.
• Firing hotter and longer = stronger. Detailed firing instructions for each brand/type/formulation of clay come in the package also can be found on the sites of the PMC Guild and Art Clay World USA. The longer and hotter you fire the clay, the stronger it becomes. If you don't fire long or hot enough, the clay will not sinter (fuse) properly and the resulting piece can break easily. It's a good idea to fire at the hottest temperature for the longest time you can (within the prescribed firing schedule for the clay you're using). In general, firing at 1650 degrees Fahrenheit for 2 hours will produce the strongest metal.
• When mixing formulations and brands of clay, always fire at the highest temperature/longest time. Different formulations of clay are fired at different temperatures and for different lengths of time. If you are mixing more than one brand, type and/or formulation of metal clay, always fire at the temperature/time required for the type that needs the highest temperature and the longest time. 
• Embed only kiln-safe stones. Whether you are firing with a torch, on a stovetop or in a kiln, make sure that any stones you embed in your clay can tolerate the necessary firing temperatures. Most lab-grown and synthetic gemstones and CZs are kiln-safe, and some natural stones (including peridot and garnet) usually can tolerate the necessary heat. To be safe, buy the stones you will be using in your metal clay pieces from a reputable supplier who can vouch for their ability to be fired safely.
• Make lemonade. One of the beauties of working with metal clay is that nearly any mistake can be corrected. Cracks can be filled and re-fired, and mistakes that can't be corrected to look as originally planned can be embellished to create unexpected new designs. Embrace the opportunity to stretch your design horizons!