WHAT IS BRONZclay™?

Welcome to the next step in the evolution of metal clay: BRONZclay™! BRONZclay 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.

FIRING BRONZclay™

Firing BRONZclay™ is a two-step process that uses low heat to prepare the kiln's atmosphere, then high heat to sinter the alloy. BRONZclay must be fired in a kiln. During firing, the non-toxic binder vaporizes, leaving a solid, pure bronze object. Note: Make sure your piece is completely dry before firing; it's not a problem for the piece to dry for weeks before firing, but firing a piece while it's still damp can cause the moisture to expand, creating blisters.

To reduce oxidation, the BRONZclay™ piece(s) must be surrounded by activated carbon during firing. The coconut shell-based carbon (#703-205) produces a light patina color; the coal-based, acid-washed carbon (#703-204) produces a colorful, more intense range of patinas.

To Fire BRONZclay™:

1. Spread 1" of activated carbon granules on the bottom of a stainless steel firing pan (#703-202).
2. Place the piece on top of the layer; if firing two or more pieces, leave at least 1/2" between pieces; leave more if the pieces are larger. Note: Most kilns are cooler in the front near the door, so the front of your firing pan will be cooler than the back and sides. Compensate for this by placing pieces closer to the sides and back of the firing container. If you're using a top-loading kiln, there's no need to adjust.
3. Pour more activated carbon granules on top of the piece until the container is full, making sure there is at least a 1/2" layer of granules on top of the piece. If you are firing several pieces in layers, make sure there is at least 1/2" of space between the vertical layers as well.
4. Cover the firing pan with its lid and place it in the kiln on stilts to allow good heat circulation.
    

   BRONZclay™ FIRING SCHEDULE

   For pieces 3mm (6 cards) thick or less: Ramp at 500°F/hour to 1550°F and hold for 2 hours (total firing time, including ramp-time, will be between 4 and 5 hours).

   For pieces thicker than 3mm (6 cards): Ramp at 250°F/hour to 1550°F and hold for 3 hours (total firing time, including ramp-time, will be about 9 hours). Note: The firing schedule for thicker pieces will work fine for thin pieces should you have both thicknesses in your firing pan.

   Warning!
   The firing pan will be extremely hot; do not touch! Allow the pan to cool completely before removing the lid. We recommend wearing heat-resistant gloves such as 12" welding gloves (#350-051 and #350-050) while removing the firing pan.
   
    
5. The firing pan should be allowed to cool completely before removing it from the kiln; however, if you need to use your kiln again right away, you can move the pan to a heat-resistant surface (e.g.: a soldering pad or ceramic tile) and allow it to cool there.
6. Once the firing pan and carbon have cooled, remove the BRONZclay™ pieces from the carbon bed and place them on a heat-resistant surface to finish cooling. You can re-use the activated carbon until you notice it starting to break down (broken grains and a sooty appearance). Note: If there are no stones embedded in the piece, it can be quenched in water.
    

The stainless steel lifting fork is ideal for removing a hot firing pan from your kiln. Gently slide the fork tines around the bottom half of the firing pan and lift the fork until the tines engage the lip at the top of the pan. Carefully lift the pan from the kiln and set it on a heat-resistant surface to cool. Note: The fork will only fit around the narrow side of the firing pan.

TIPS FOR WORKING WITH BRONZclay™

BRONZclay™, like any clay, is highly workable; but, because it is a metal clay, it has its own characteristics as well. Here are some tips for working with BRONZclay:

When you're not using BRONZclay™, keep it tightly wrapped in plastic and sealed in
a plastic bag for extra protection against drying. Store all BRONZclay in a refrigerator
until you're ready to use it. Refrigerate the clay between sessions, too.

Rub a dab of olive oil on your hands and tools before you begin working with the clay.

BRONZclay™ tends to dry quickly. You'll notice the clay stiffening and cracking when it begins to dry. While working the clay, refresh it periodically with a small amount of water using a spray bottle or brush.

Keep pieces wrapped in plastic and placed to the side when they are not actively being worked.

Avoid using tools that absorb water.

After prolonged exposure to air, BRONZclay™ develops a black surface. Scrape away this black layer until you reach the useable clay, which will be unaffected and ready to use

DRYING BRONZclay™

You will need to dry your BRONZclay™ piece thoroughly before firing to prevent moisture in the clay from expanding and creating defects during firing. To dry the piece, gently place it on a warming surface such as a coffee mug warmer or a vegetable dehydrator. When dry, the clay will be leather-hard, making it flexible and amenable to finishing touches such as filing, drilling, sanding and carving. After firing, this work is more time-consuming, so take advantage of this pre-fired stage to do as much of your detailed finishing work as possible.

BASIC FORMING TECHNIQUES

Rub a few drops of olive oil on your palms and tools before starting to keep them from sticking to the clay and to keep the clay moist.

To make sheets, use a roller and stir sticks or two equal stacks of playing cards on each side of the lump to make a uniform thickness (thicknesses of 3-6 cards are typical for jewelry items).

A knife, X-Acto® blade or playing card edge can be used to lift the pieces off the sheet.

To join parts, set them close together and apply a drop of water and slip with a pointed brush. Let the water penetrate for a few seconds, then firmly press the parts together and hold them in place for several seconds.

To achieve textures, press the BRONZclay™ against a rough surface or roll the surface over a sheet of BRONZclay. Even simple objects such as bottle caps create interesting trails, and leaves, bark and wood offer many possibilities.

One way to make a pendant bail is to roll out a slender rod and form it into a loop. Cut off the ends to make a solid attachment, moisten with water and press it into position.

To make rings, wrap enough wide tape around a dowel to create a form of the correct size (remember to allow roughly 20% for shrinkage). Cover the form with plastic wrap and create your ring. When it is finished (and preferably before the clay dries), slide the ring off.

Note: If the BRONZclay™ becomes dry as you work, spray or brush on a little water (not too much!) and cover it with plastic wrap for a few minutes to allow it to rehydrate. If you add too much water, just set the clay aside, loosely wrapped, and allow it to dry out.

FINISHING BRONZclay™

Once fired, the BRONZclay™ piece is solid metal and, like any other metal, it can be sawn, drilled, sanded, patinaed or soldered using traditional jewelry tools and materials.

Hand-Burnishing

Perhaps the most basic (and rewarding) way to polish BRONZclay™ is to rub it with any hard, smooth object. Commercial burnishers offer a time-tested tool shape held in a comfortable handle, but you can use knitting needles, teaspoons or polished wood nails. Rub the piece in all directions to bring out a shine. Follow this with a polishing cloth to smooth away burnishing marks.

Spectrum™ Finishing Papers

The screen mesh structure of Spectrum™ finishing papers resists loading to increase their effectiveness and help extend service life. Each sheet is reversible, doubling its useable surface area. The synthetic fiber backing of carefully graded white aluminum oxide abrasive can be used wet or dry and is especially effective on BRONZclay™. Sheets measure 8-1/4" x 11".

Scratch-Brushing

Brushes made from very thin stainless steel wires can be used to burnish BRONZclay™. Lubricate the brush with any sort of soap and work under a slow drizzle of water. Scrub in all directions. Scratch-brushing can be used in conjunction with any other technique.

Mass Finishing

A rotary tumbler is a mechanical device in which hundreds of steel balls and rods cascade against jewelry objects as they rotate in a drum like a miniature clothes dryer. Using this method, many pieces can be finished at once with minimal individual handling. A magnetic finisher with steel rods is also a very effective choice.

MAKING AND USING SLIP

Making Slip

Slip will quickly become one of your favorite tools for working with BRONZclay™, and it's easy to make. Simply mix tiny pieces of clay (filings, small fresh or dried pieces, etc.) with water (we recommend distilled water) until you reach a toothpaste consistency. Keep your slip stored in a sealed container; stir before using. Note: Slip lasts for about one week, so make only enough for your immediate need.

Making Repairs

Because of its strength, BRONZclay™ slip is suitable for attaching parts, repairing breaks and reinforcing delicate areas such as the point where a loop attaches to a pendant.

Transitioning

Use slip to fill between elements when creating an organic effect

ADDING STONES TO BRONZclay™

Add CZs or certain lab-created stones to BRONZclay™ to add design versatility. Because these particular gems are composed of laboratory-grown corundum, spinel or CZ, and are created at very high temperatures, they will not be damaged during firing. We do not recommend firing precious natural stones, most glass objects or any organic material such as pearl, opal, bone, shell and wood. Important: Never fire a doublet.

To Set a Small Faceted Stone

1. Prepare a seat or rim that will provide enough metal to surround the stone. This can be added to a completed form or built into the original design.
2. Make a conical hole with a pencil point or similar tool.
3. Use a straw or similar tool to remove clay from beneath the stone.
4. Set the stone in place and press it down until the table is below the surface of the work. Remember that the clay around and under the stone will contract, squeezing the stone upward.
5. Fire as usual; cool in the oven to prevent thermal shock.

MAKING MOLDS AND MORE

BRONZclay™ lends itself easily to working with molds you make yourself or with commercially made molds. Molds allow for repeated elements and the production of multiples. Hollow forms allow your work to be light. Here are some ideas for molds:

Soap

A simple way to get started is to carve a pattern into a bar of soap. Press BRONZclay™ into the depression, peel it away, and you have a molded form. If you don't like the result, re-work the carving and try again. Need a dozen? It's a simple matter of repetition.

Rubber Molds

Hobby shops sell a variety of molds intended for candy, candles and plaster. Specialty kitchen shops may be a good source for interesting cookie, butter or gelatin molds. All will work for BRONZclay™.

To make your own molds, buy a two-part silicone mold compound (such as Rio Cold-Mold™,
shown below). Most molds do not need lubrication, but if the clay sticks, spray the mold lightly
with an aerosol cooking oil.