Using metal clay molds

Start with one idea: Create an original piece of art using polymer clay, bake it, and then make a silicone mold from that piece. Add a second idea: Use various metal clays (each with different shrinkage rates) to make multiple metal-clay elements—turning those that shrink less into pendants and those that shrink more into earrings. Continue with a third idea: Make silicone molds from the sintered metal-clay elements and use the new molds to make even smaller metal-clay components for a daintier set of earrings. You could go on ad infinitum!

Consider this about metal clay: One type shrinks as much as 25–30 percent as it sinters; another, only 8–9 percent; and still others, somewhere in the 10–15 percent range. By taking advantage of what some may consider metal clay’s drawbacks, you can turn a potential design disadvantage into a strength.

Starting with a polymer-clay model means you can create an original mold with the exact look you want. You may experiment with the design without worrying whether the metal clay is drying out. When you are finished with this project, you will not only have a great-looking set of jewelry, but your mind will also be sharper when it comes to working with metal clay and factoring shrinkage into your designs.

The instructions below begin after you have made a polymer clay piece. For the complete project instructions and additional tips, click here for the free project PDF.

Materials

• Polymer clay, 3 ounces (84g), any color (or waste)
• Liquid polymer clay
• Two-part silicone mold compound
• Metal clay, 14g (shrinkage rate of 8–15 percent)
• Metal clay, 28g (shrinkage rate of 25–30 percent)
• Sterling-silver wire, 21 inches (53.3cm), 22-gauge
• 3 round beads, 4mm
• 3 sterling-silver spacer beads, 3*5mm
• Chain for necklace
• 2 ear wires
• Keum-boo foil (optional)

Tools & supplies

• Pasta machine* and/or deck of playing cards
• Acrylic roller or PVC pipe
• Cornstarch
• Texture sheet
• Circle template
• Square template
• Needle tool
• 2 straight-edged tools
• Paper towel
• 2 pieces of wire screen, different patterns
• Small objects: rubber M stamp, crescent moon, polymer-formed spiral, trilobite fossil, or others
• Craft knife
• Hotplate or toaster oven*
• 2 heavy plastic sheets
• Olive oil
• Jeweler’s file, flat
• Kiln with ceramic-fiber shelf
• Brass brush
• Wire cutters
• Round- and chainnose pliers
• Steel bench block
• Hammer
• Keum-boo tools (optional)
• Tumbler with stainless-steel shot and burnishing compound (optional)
• Liver of sulfur (optional)

* Dedicated to nonfood use.

Instructions

[1–2] Make a silicone mold. Using a two-part silicone mold compound, take a walnut-size piece of each part and use your fingers to knead them together until they are mixed completely. Since the parts usually are two different colors, mix them until a uniform color is achieved.

Working quickly, shape the molding compound so it is a little larger than the textured polymer-clay piece you made for this project. Put it on your work surface. Place your baked polymer-clay piece face down on top of the compound and press until the top of the textured polymer-clay piece is flush with the top of the compound. Press firmly so all the textures are captured in the silicone mold.

Let the compound set for 12–15 minutes. It is cured when you press your fingernail into it and the mark heals itself. Gently flex the mold to remove the polymer-clay piece.

[3] Make the metal-clay pieces. Roll out the metal clay. Start with approximately 14g of metal clay that shrinks in the 8–15 percent range. Working on a heavy plastic sheet that is lightly coated with olive oil, roll the lump of metal clay into a circle that is 4 playing cards thick.

Place the silicone mold face up on the work surface. Silicone molds do not have to be oiled before using them with metal clay. Place the metal-clay circle on top of the mold and gently press down, making sure the metal clay gets into all the textured areas of the mold. Trim the excess metal clay from around the mold and the raised-square area in the center.

Gently flex the mold, releasing the metal-clay piece. Place the metal clay on the oiled plastic. Allow the clay to dry as is, or speed up the process by placing it on a hotplate or in a toaster oven set to low.

Repeat using metal clay that shrinks 25–30 percent to create two disks to use for earrings.

Finish and fire the clay. When the metal clay is leather hard, use a flat jeweler’s file to sand the outer edge of the element and the inside edges of the square center. Place the metal clay on a ceramic-fiber kiln shelf and fire it according to the clay manufacturer’s directions. You may have to do separate firings for clays that require different firing times and temperatures.

When the metal clay is cool, use a brass brush to burnish away the white appearance of the sintered silver, but if you want to do keum-boo on some of the areas, do it before burnishing. For more information on this process, see Celie Fago’s book, Keum-Boo on Silver.

For a shinier finish, place the burnished pieces in a tumbler with stainless-steel shot and burnishing compound for 10–30 minutes. Rinse and dry the pieces after tumbling.

Add a liver of sulfur patina if desired. Be sure to follow the manufacturer’s directions for the product you are using.

To read the rest of the project instructions, click here for the free project PDF.