How Do You Use Precious Metal Clay?

What is Precious Metal Clay?

Precious Metal Clay (PMC) is a crafting material made from precious metal particles like silver or gold suspended in an organic binder. It has a soft, clay-like texture that allows it to be hand-shaped into detailed designs. Once shaped and allowed to dry, the pieces are fired in a kiln, burning away the binder and fusing the metal particles into a solid, 99% pure precious metal artwork.

The most common type of PMC is silver clay, made from pure silver particles. However, PMC also comes in gold, copper, and bronze clays. The ingredients are simple: finely divided precious metal powders combined with an organic binder and water. The binder is often a plant-based substance like cornstarch or methyl cellulose.

Some of the main types of precious metal clay include:

• Standard Clay – The original formula, suitable for most applications.
• Paste Clay – A thicker clay for adding textures and appliques.
• Paper Clay – Thin sheets for cutting out shapes or wrapping.
• Slip Clay – A liquid clay used like glue or for joining pieces.

The different types allow a wide range of jewelry designs and techniques using PMC.

Tools and Supplies Needed

When working with precious metal clay (PMC), you’ll need a variety of basic tools and supplies on hand to create your pieces. Having the right setup will make working with PMC easier and ensure success. Here are some of the key tools you’ll need:

Clay – The PMC itself comes in a variety of formulas with different precious metal contents. Choose the type suitable for your project. You’ll need enough clay for the size and number of pieces you plan to make.

Work Surface – This can be a smooth glass work surface or tile that can withstand the heat of fired clay. Keep your work area and tools clean.

Blades – X-Acto knife, tissue blades, or clay cutting blades to cut and shape the clay.

Roller – An acrylic roller to flatten and condition clay before working. A clay roller with ring handles provides good control.

Texture Sheets – Flexible rubbery sheets can press patterns into the clay. Use them to add interest and design elements.

Cutters – Metal cutters and formers in different shapes help cut and mold clay shapes efficiently.

Kiln – You’ll need a kiln suited for firing PMC, able to reach temperatures between 1475-1650°F.

Firing Container – Such as a stainless steel firing pan or fiber blanket to fire your pieces safely.

Conditioning the Clay

Properly conditioning your precious metal clay is one of the most important steps in working with PMC. The clay must be kneaded thoroughly in order to achieve an optimal consistency before shaping begins. Kneading helps to distribute moisture evenly throughout the clay and removes any air bubbles that may have formed during packaging or shipping.

Start by cutting off a workable piece of clay from your block. The amount you cut off will depend on the size of the piece you intend to make. Roll the clay into a ball and begin kneading it in your hands. Apply even pressure as you push, pull, and squeeze the clay repeatedly. Fold the clay over itself and continue kneading to blend it thoroughly.

As you knead, you’ll notice the clay becoming more pliable. If it feels stiff or crumbly, spritz a small amount of water and continue kneading to incorporate it. The clay is ready for shaping when it has an even, smooth, clay-like consistency—not too stiff or sticky. Properly conditioned PMC is soft but not tacky. Kneading for 5-10 minutes is usually sufficient.

If the clay ever starts to dry out, add a little more water and knead it in. Try not to over-wet the clay though, as excess moisture can cause cracking or explode into steam during firing. When in doubt, it’s better to have clay that’s slightly too dry versus too wet.

Shaping the Clay

Once the PMC is properly conditioned, it’s ready to be shaped into your desired design. There are several techniques for shaping precious metal clay:

Rolling

If you want to create a flat sheet or slab, you can use a rod or acrylic roller to roll out the clay to your desired thickness. Dust the work surface and roller lightly with mica powder to prevent sticking. Roll from the center outward using even pressure. Rotate the clay 90 degrees periodically to ensure uniform thickness.

Cutting

Use tissue blades, craft knives, or various cutters to cut shapes out of rolled sheets or slabs of PMC. Cut gently with a rocking motion to get clean edges. You can also use cutters like cookie cutters to punch out shapes.

Molding

Press clay into silicone molds or forms to create 3D shapes or detailed textures. Apply a light dusting of mica powder so the clay releases more easily. Flexible molds work best. Allow the clay to dry completely before removing it from the mold.

Sculpting

PMC can be hand sculpted just like any clay. Use tools like ribs, loop tools, and rubber tipped clay shapers to sculpt free-form shapes. Add armatures or foam shapes if support is needed. Let your creativity guide you in sculpting original designs.

Applying Textures and Patterns

One of the great things about precious metal clay is how easy it is to apply textures and patterns to your creation. There are a few different techniques you can use:

Texture Sheets

Texture sheets provide an easy way to impart patterns onto your clay. These are thin flexible sheets that have various designs etched into them. To use them, lay the sheet over your clay then run a roller over it. This will press the design into the surface of the clay. Some common textures include basketweave, scales, and stone. Play around with layering multiple texture sheets to create more complex designs.

Roller Patterns

You can also find rollers that have patterns etched into them. As you roll over the clay, the design gets transferred. There are rollers with geometric patterns, nature motifs, and more. Use these to quickly add ornate designs to your clay.

Stamping

Rubber stamps are another great texturing option. Press these into the clay to leave behind imprints of the stamp design. You can find stamps with floral patterns, alphabets, and custom motifs. For more control, use stamping tools like those used for printmaking. These allow you to apply as much or as little pressure as needed to get the right impression.

Get creative with layering textures and alternating stamp orientations. This can yield truly unique patterns and designs in your precious metal clay creations.

Allowing to Dry

Once you have shaped your precious metal clay piece, it’s important to allow it to dry fully before firing. As the water evaporates from the clay, the binders start to burn away. If you fire a piece before it is completely dry, steam and gases can become trapped inside and cause cracks or blisters.

Make sure your piece is bone dry by letting it sit at room temperature for 24 hours. Avoid drying in direct sunlight or near heating sources, which can cause uneven drying. Place the piece on a mesh screen or glazed ceramic to allow airflow all around.

As the clay dries, it will shrink slightly. To prevent warping or cracking, avoid drying too quickly. Thick areas may take longer to dry than thin areas. If warping starts to occur, you can place the piece between two ceramic tiles or mesh screens while drying to keep it flat.

Check your piece before firing to ensure there are no soft or tacky areas, which indicate moisture remaining. The clay should be completely hardened and have a matte appearance when totally dry and ready for the kiln.

Firing the Clay

Firing is the most important step in working with precious metal clay. It sinters the fine silver or gold particles together, burning away all binders and organics to leave a pure precious metal object.

There are two main ways to fire PMC – using a kiln or using a handheld torch. Kiln firing provides more even heating and better results, especially for larger or complex pieces. Torch firing with a handheld propane/butane torch allows more flexibility but can lead to uneven firing if not done properly.

The recommended firing schedule will depend on the type and brand of PMC used. Most clays fire at temperatures between 1100-1600°F (600-900°C). It’s critical to follow the manufacturer’s firing guidelines to avoid under-firing or over-firing the piece.

When using a kiln, place the dry PMC piece on a layer of kiln posts on a metal firing pan, and program the kiln with the recommended ramp up rate, hold time and cooling cycle. Monitor with a kiln sitter or pyrometer if possible. When torch firing, use an even circular motion about 2-4 inches from the piece, making sure to heat the entire piece thoroughly.

After firing, the pure silver or gold piece can be carefully quenched to cool rapidly. Finish and polish with fine wet sandpapers, buffing wheels or specialized PMC polishing systems to reveal the pure precious metal surface.

Finishing and Polishing

After firing, precious metal clay pieces will have a matte, grainy texture. Finishing and polishing is done to smooth the surface and bring out the metallic shine. There are several techniques that can be used:

Filing

Filing with a jewelers file can flatten seam lines and shape edges. Move the file in one direction across the metal, applying light pressure. Be sure to support the piece being filed so it doesn’t bend or warp.

Sanding

Use wet/dry sandpaper to smooth the surface. Start with a lower grit sandpaper like 400 and work up to higher grits like 600 or 1000 for a polished finish. Rub the sandpaper across the metal, rinsing often. Sanding can be done before or after polishing.

Buffing

Buffing wheels charged with polishing compounds can quickly achieve a brilliant shine. Apply buffing compound to the wheel and hold the PMC piece gently against the spinning wheel to buff. Use a softer wheel first then move to harder wheels for a final shine.

Polishing

A jeweler’s polishing cloth with a fine polishing compound can also be used to polish PMC pieces. Rub the piece against the cloth in a circular motion until you achieve the desired luster. Rinse the piece periodically while polishing to remove residue.

Setting Stones (Optional)

One of the great things about precious metal clay is that you can easily set stones directly into your finished pieces. This allows you to add color, texture, and sparkle to your PMC creations. There are a few simple steps for setting stones:

Cutting Seats

You’ll need to cut a seat or setting for each stone you plan to set. This can be done by cutting out a space in the desired shape and size using hand tools before firing the PMC piece. Or you can drill a hole into the fired clay using a diamond drill bit or cutting disk. The seat should be slightly smaller than the stone to create a tight fit.

Securing Stones

Once your seats are ready, place your chosen stones and secure them by pressing them firmly into the setting. You may also want to apply a high temperature kiln paste around the edges of the stone to help hold it in place. The firing process will shrink the metal clay around the stone to create a tight, secure setting.

With some simple tools and techniques, you can easily set stones into your finished PMC pieces for beautiful results. Just be sure to plan ahead for where you want stones placed when designing your original piece.

Caring for PMC Pieces

Proper care and maintenance is important for preserving precious metal clay (PMC) pieces. Here are some tips for keeping your PMC jewelry looking its best:

Cleaning

PMC can be cleaned with a mild jewelry cleaner or dish soap and warm water. Gently scrub the piece with a soft brush to remove dirt and oils. Rinse thoroughly and pat dry with a soft cloth.

Avoid using ultrasonic cleaners or harsh chemicals like ammonia, bleach or acetone as these can damage the metal.

Storage

Store finished PMC pieces in resealable plastic bags or covered containers to prevent tarnishing. You can also add anti-tarnish strips to help prevent discoloration over time.

Keep pieces in a cool, dry place and avoid exposure to direct sunlight for long periods.

Repair

Minor scratches or dents in PMC can often be gently rubbed out with very fine sandpaper or a fiberglass brush. For cracks or broken areas, new PMC can be applied and re-fired to mend the piece.

Seal any repaired areas with a thin layer of liquid clay or PMC paste before refiring to help blend the repair. Take care not to overfire when repairing existing pieces.