BRONZclay is a non-toxic metal clay product used by jewelry artists and craftspeople to create one-of-a kind and small run jewelry, models, prototypes, sculpture and decorative items.
Just about anything you can image can be sculpted, formed or molded using the moist clay. Objects are fired in a table top kiln to transform them into solid bronze metal. Gemstones and some other items can be embedded in the wet clay and fired together. After firing, the metal is polished and finished. The final product is actual metal because the clay is made of real metal powders.
Bronze is an Alloy. Just like there are lots of different kinds of fruits with different shapes and tastes and nutritional values or "properties", each metal and metal alloy has a unique set of physical properties.An alloy is a word used to describe metals that have been mixed together. There are special alloys (think of it as a recipe) for specific uses. If we mix some amount of tin into copper, we call it bronze. The amount of tin added affects the properties of the alloy. There are special bronze alloys that used for many surprising things, such as a special alloy just for making bells. Too much tin in the recipe and there's no ring to it!
Creating with BRONZclay is used like ordinary modeling clay, but has a few differences that require slightly different tools than those used with earthen clays.My list of basic tools will serve as your core tool kit. Additional tools can be gathered from every room in your home to texture, form and shape your BRONZclay creations, and nature offers an endless supply of textures and ideas to draw from.
For those who work in silver clay, you'll need a separate set of "dusty" tools for BRONZclay to avoid cross-contamination. Unfired dust and bits of BRONZclay clay must be kept separate from silver clay. Needle files and diamonds files should have a set dedicated to BRONZclay. Brushing the dust off the tools is not good enough. The tools must not mingle. The rule is easy: if the tool creates dust or if dust builds up on it, keep a separate set for BRONZclay.
After the metal is sintered, files, sanding sticks, polishing papers and other metal working tools can be used both on silver and bronze.
Tip: Cool Slip sprayed on a cleaning cloth makes an excellent cleaner for removing metal clay residue from tools and provides an anti-stick coating at the same time.
Tip: Keep a sanding tray handy with all your BRONZclay sanding tools in it. Use the tray in your lap or in your sweeps drawer as you work. The entire tray can be moved out of the way when not in use.
Basic BRONZclay Tools: Cool Tools Product Code: KIT-401
Bronze/Copper Complete Tool Kit
Worksurface - Teflon, laminate, glass, silicone all make great surfaces
Claymate Hand Conditioner - To keep clay from sticking to your hands
Glove in a Bottle - Hand sealer
Cool Slip Anti-Stick Spray - Releases clay from textures, surfaces
Lavender Oil - Use to make Lavender water to inhibit oxidation
Rolling Tool - To roll out slabs of clay
Cards - Use to gauge the thickness of the clay
Needle Tool - For cutting clay
Scalpel or Xacto Knife - A craft knife that can be used to trim, sculpt, cut the clay when wet or dry
Tissue Blade - To cut long strips of clay
Pallete Knife - Use to mix paste, cut clay, smooth edges
Mixing Plate - This is a small disc used to mix the paste
Snake Roller - Used to roll out lengths of clay snakes
Blending Tool - Silicone tipped tool for blending clay
Paint Brush - A good quality brush to apply water to the clay
Rubber Bench Block - For working and finishing
Swivel Vice - To hold drills for making holes
Drill- 2.5mm and 3mm drills for drilling holes
Diamond Tweezers - For handling gems and small parts
Bent Tip Tweezers - For gems and small parts
Sponge Sanders - Use to shape and refine the dry clay
Diamond Needle Files and Burs* - Great for shaping, carving and sanding
Millimeter Gauge - To determine firing schedule of the clay
Wet/Dry Sandpapers 220 & 400 grit - For finishing
Polishing Papers - For finishing to a high shine
Polishing Cloth - For polishing
Cling Wrap - For air-tight wrapping of the clay, the thickest you can find
Water Dish* - To hold water
Sanding Tray - To catch the dust and bits when sanding, carving and shaping dry clay
In addition to these tools, of course, is an endless list of texture and tool possibilities that you can add as you go along. *Not included in the kit, but highly recommended
BRONZclay comes packaged in blocks of 100 grams and 200 grams. There is no paste, syringe or paper currently available. BRONZclay Storage:Keep your BRONZclay happy and fresh by storing it in the refrigerator.
BRONZclay prefers to be cool and stiffens as it warms, so unopened packages should be stored in the refrigerator. For opened clay, wrap tightly to exclude air, clip, and then place in a plastic bag with a damp sponge (not wet). Place this bag in the refrigerator. A home vacuum sealer is great for air-tight sealing.
Ideal Workspace For BRONZclay
BRONZclay prefers a cool, moist environment. Most basements make great metal clay studios because they offer naturally cool temperatures and high humidity. A cool room (72F or cooler) with good humidity (at least 50%) and indirect natural light is ideal for BRONZclay working. If you do not have perfect BRONZclay conditions in your studio, you can simulate them. Use a humidifier to increase the moisture in the air. Set the temperature to 72F. Avoid warm rooms. BRONZclay stiffens as it warms, so the warmer the room, the harden the clay will be to work with. Do not work outside or in direct sunlight. Drafts or air blowing across your work area or from overhead will accelerate drying of the clay. Air conditioners and heaters both dry the air, so add humidity when running either appliance. A work space can be anything from a tray on your lap to a dedicated studio designed and built for metal clay work. At the very least, you need a comfortable chair, good lighting, a work surface and magnification.
Comfort is essential in creating. A chair that puts a hitch in your get-a-long will probably put a hitch in your metal clay productivity and enthusiasm as well. I use an adjustable height chair because my bench needs to be at different heights for different tasks. An adjustable height chair allows me to stay at one workplace with one chair and do multiple tasks. When I'm working in wet metal clay, I want my chair at desk height. When shaping, filing, sanding, drilling, polishing at the bench pin, I want my chair much lower. The determine the correct height for your chair, sit with your back straight. Rest your elbow on the table. Lower your chair until your arm is parallel with the floor. Not all adjustable chairs have the full range of adjustment needed, so try out a chair before you buy it and make sure you have all the travel you need. If you have the luxury of space, you can set up different work stations for different tasks and provide the right chair for each station.
The type of lighting needed depends on the job at hand. Indirect natural lighting is the first choice for general clay working.. If artificial lighting is needed, choose full-spectrum or daylight balanced bulbs. Daylight and full spectrum bulbs offer economical natural-looking light to brighten things up without adding heat to a room. If you have only overhead lighting, you might consider an articulated task light that can be set at any height or angle and use cool, low-wattage bulbs. A graphics or drafting type light or and Ott Lite is a great choice.
Seeing Things Clearly
The x-ray vision I had as a kid is long gone. I use 2.5+ readers for general work, an Optivisor for fabrication, soldering, polishing, finishing, etc, and a <10 power loupe to inspect stones and other super fine details.
BRONZclay is very stiff right out of the package and must be kneaded to make it soft and pliable before it can be worked. Fresh BRONZclay can also be somewhat sticky, so you will need to condition your hands with something the clay will not stick to. BRONZclay contains water, so a water-repellent coating is needed to keep the clay from sticking to your hands. Some use straight olive oil, others use balms made from olive oil such as Badger Balm and Burts Bees. Cool Tools makes Slik which is a soy-based balm and Claymate which is a cream. Both products were formulated for metal clay and do not contain olive oil. Some people find that the copper in BRONZclay irritates or stains the skin.
Gloves in a Bottle is another product that can be used to seal the skin prior to working. (It is also wonderful for all sorts of other skin conditions). Try what you have on hand and see how it works for you. If your hands become stained, try something else until you find the best product for your skin type. When you have the right release, there will be no staining or sticking.
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Do not use any type of petroleum-based product with BRONZclay (or any other metal clay). Vaseline is a petroleum jelly, so it cannot be used as a release. Do not use industrial lubricants such as WD-40 or silicone spray lubricants.
To keep BRONZclay cool at my bench, I've made a little cooler out plastic storage containers. When I'm not working with the clay ball, I put it inside the cooling well. This cools the clay very quickly and makes it very workable. To make a clay cooler use 2 nesting containers, one larger than the other. I fill the bottom container with ice, nest the smaller one inside (photo near right) and cover the unit with aluminum foil, as shown in the photo on the far right. The lid to the larger container is used under the unit to catch water as it condensates, avoiding a puddle on the workbench. The lid to the smaller container is used to cover the cooling well. The ice well (the larger container) can be filled with ice cubes, or the whole unit can be frozen. Ice cubes lasted about 3 hours in my studio. In the photo at the right, I have filled the container partly with water and froze the smaller container in place. This will last much longer than ice. Add weight inside of the smaller container so it bouys about 1" from the bottom of the container. This way you will end up with the smaller container sunk deep in the ice.
I first apply Claymate or Gloves in a bottle to my hands. Both products contain an ingredient that bonds to your skin to keep the properly conditioned clay from sticking to or staining your hands. For best results, allow Claymate or Gloves in a Bottle to dry on your hands before beginning work with the clay.
The goal in conditioning is to achieve the proper consistency and then maintain it throughout a working session and when in storage. The clay is stiff when freshly opened and the amount of moisture in the clay can vary from package to package. You'll need to learn to recognize when the clay needs more or less water and rehydrate as needed.
After opening a fresh package or clay, I first test the clay surface for stickiness by pressing my finger lightly on the clay. If any clay sticks, I let the clay sit for 30 seconds or so to allow some of the moisture to evaporate from the surface. Test again (with a different finger), and when my finger comes away clean, I turn the lump over and let the other side evaporate a little so it's not so sticky.
A 100 gram package contains a single bar of clay. A 200 gram package contains two 100 gram bars that are scored in the middle for easy separation. I work with 100 grams at a time. If I have a 200 gram pack, I wrap one of the 100 gram bars in cling wrap and set aside while I knead the other one.
I break a 100 gram bar in half and stack the two halves. I use my thumbs to press lightly from the center outward to form a patty about 1/4" thick. I avoid touching the outside edges of the clay which are very moist and sticky, and no matter what you condition you hands with, this stiky kind of clay will stick to to your fingers, so try not to touch it. I also go very lightly so I don't break through the "crust" of the surface.
Once I've formed a rough patty, I fold the sticky outer edges to the center of the patty and then continue folding the edges in until I have a nice ball.
Now all the wet sticky parts of the clay have been worked in and I can freely touch the clay without any stick to or staining my fingers. I knead the clay until pliable and smooth, then flatten it into a patty about 3" across.
Next, I smear Slik on one side of the patty, keeping just a litle away from the edges. Then fold in the edges to the center, form a ball and roll out the clay a few times. Add another smear of Slik and knead and roll out again, then form a ball. The clay should feel piable, cool and moist but should not be sticky. If it's too dry, you can smear a paintbush of water over the surface and rehydrate. Once the clay is at the right consistency and moisture content, form it into a ball.
Place the ball of clay in the center of a 12" x 12" sheet of cling wrap. Twist the plastic around the ball and wrap the excess plastic around that. I hold the plastic in place with a chip clip or some other large-sized clip or rubber band and set it aside to rest.
It's important to allow the clay to rest after kneading because working it with my hands heats up the clay. BRONZclay stiffens as it warms, and even body heat is enough to stiffen the clay. Keep in mind that the binders in BRONZclay are different than those in silver clay, so this is a property unique to BRONZclay. I like to keep 2 balls of clay so one can rest and cool while I use the other. Lavender Water
Put a drop of pure lavender essential oil in your water dish at a rate of 1 or 2 drops per 1/4 cup of distilled water. Lavender oil slows the oxidation of copper.
Use lavender water to re-hydrate, make paste and moisten BRONZclay. I've kept a dish of lavender water on my bench for several days with no signs of oxidation. If the bits that settle at the bottom of your water container become dark, dscard the water, clean out your water dish and make a fresh batch.
Lavender essential oil has been used throughout the ages as an antiseptic (kills germs), anti-inflammatory (controls swelling), insect repellent, (lice, fleas and spiders steer clear of it). Give a bottle of Lavender Water to your teenager...it's said to help clear acne. Distilled Water Use only distilled water when working with BRONZclay to avoid contaminating the clay with impurities and additives from well or city water supplies.
BRONZclay can be rehydrated to add moisture to a working lump or to make clay or paste from totally dried bits and filings.
Lump clay is re-hydrated regularly during a working session as needed. I re-hydrate lump clay several times over a work period, and it's very easy to do. One caution, though, trying to re-hydrate too large a lump at once can lead to a muddy mess. I can rehydrate about 50 grams at a time. First make a patty about 4 cards thick. Use your fingers and your calibrated eye; it doesn't have to be exact. Paint water over the clay patty, avoiding the very edges. The patty should just be moistened, not dripping. Fold the edges into the center, being very gentle and watching for water that might want to ooze up in the center. If you have the right amount of water, there will be no oozing. If some water oozes out the middle, blot it off so you don't end up with mud. Keep your fingers on the dry clay, folding in the sides of the patty, pressing them down and working into the middle of the ball. Then knead until smooth and pliable. At this point, I wrap the clay and let it rest so the binders can fully absorb the moisture. If you add water and the clay still feels too dry, add more.
Dried bits and filing can be re-hydrated to make paste or lump clay. The filings must be clean and free of foreign particles. Some sandpapers and salon boards shed abrasive particles as they are used, so you may wish to use only the bits from filing and carving. I use a mortar and pestle to grind the clay bits into powder, then add in distilled water a few drops at a time (I use a dropper). Stir with the palette knife. Add in more water as needed to form a dough. Once a dough is formed, use a mini bowl scraper to turn the clay out onto a piece of cling wrap, wrap tightly and allow to rest.
Tip: Make a drilling block from BRONZclay. When you want to drill a clean hole in dry clay, you need to drill all the way through the clay and out the other side. If you drill into a block of the same material, you will create dust of the same material, which means no contamination of a foreign material. Here's how to make a drilling block: Form a slab of BRONZclay 1/2" thick and cut into a square or circle. Air dry for the first hour, turning the piece every 15 minutes for even drying. Then place in dehydrator and dry as normal or, leave to air dry. A 1/2" thick piece will take about 6 hours to dry in a dehydrator and several days to air-dry completely.
BRONZclay does not sinter well when too much water has been added, so I aim for the consistency of peanut butter when I make paste. I mix paste on a flat surface using a palette knife. I use a flat disc that I hold in the palm of my hand. The disc is a really handy way to make and use the paste. I use the palette knife to cut a small bit of clay off the lump and wipe it onto the disc. I paint the clay with lavender water (lavender water keeps the clay from oxidizing) and mix into the clay with the palette knife. I make up just what I want for the moment and always have fresh paste that is the exact consistency I need. I like the acrylic disc because the paste stays put when it's wet and slides right off when dry. The paste can be allowed to dry and re-hydrated for use later.
Burnable forms give support during creation and drying. When you fire pieces formed over cork clay, paper clay or any other combustible form, be sure it is properly supported during firing. The burnable forms offer no support during firing. Be aware that cork clay does not completely burn out in a BRONZclay firing. Creative Paper Clay leaves a residue of volcanic ash.
Place your pieces in the firing pan so that gravity has the least chance of collapsing the form. Use an appropriate thickness for the item to support itself. A head for physics will help, but whatever item you make, keep in mind that it needs to have integral strength in the design and thickness to maintain it's shape during firing. Larger pieces need to be thicker than smaller pieces, but too thick willcause a collapse from the weight. Here are some thickness suggestions for support using a domed disc as an example:
Arrange pieces in the firing pan so that they do not have the pressure of gravity working against them. A domed disc should be placed so the dome side is down in the carbon, horizontally. Lentils, on the other hand, are two domes put together. They should be oriented vertically to counteract gravity. Round beads only need to be thick enough to support the span of their circumference.
If you want pieces to bond, attach the parts with lump clay or very thick paste made from lump clay. Pieces can be added when wet, or when dry. To paste dried pieces together, first moisten the areas to be attached with a damp brush, apply the clay-paste to one or both of the parts and press the parts together so they "seat", but do not use excessive pressure. If you used a generous amount of clay/paste, some of it may squeeze out from the joint. You can use a clay shaper to rub this in now or file it smooth later.
BRONZclay extrudes beautifully through syringes and extruders. The clay should be freshly conditioned and have a soft, pliable texture before loading into the extruder or syringe. Extruding through a syringe can be a challenge to those with weak hands, but our syringe accessory makes it much easier. As a test, I extruded BRONZclay from a syringe onto a pre-formed ring. No attempt was made to adhere the syringe. It was just extruded, dried and fired on the ring. All of the syringe fused to the ring.
Embedding and Co-Firing
Most cubic zirconia and lab created gemstones can be fired in place in BRONZclay. In fact, most stones are relieved of their time and temperature limiations when fired in activated carbon. This is very interesting and fortunate because now we can use those gorgeous tanzanite cubic zirconia stones that we all love, but burn in silver clay at very low temperatures. More on gemstones can be found in my BRONZclay firing article.
- - Glass cannot be co-fired with BRONZclay. The firings are too long and too hot.
- - Sterling silver and fine silver cannot be co-fired with the BRONZclay. The metals will attempt to alloy (mix) with each other in an unattractive way.
- - Precious metal clay cannot be co-fired with BRONZclay. These two clays can be combined, but not during the sintering phase of BRONZclay.
- - Copper, Brass and Bronze can be embedded in BRONZclay and co-fired.
Sterling and fine silver findings cannot be fired in place in BRONZclay. As the bronze sinters, the silver will try to alloy with it. The result is rather ugly. Brass, bronze and copper can be fired in place with bronze clay. Brass finding can be fired in place with BRONZclay.
I do not recommend using brass, bronze or copper for ear wires because the high-copper content in these metals can cause piercings to become sore and infected. Use sterling silver, fine silver or karat gold wires for earrings and posts.
A sterling silver post was inserted through a hole in a test piece and fired according to the 3-Hour Firing Schedule. The sterling silver attempted to alloy with the bronze. The white area in the center is what's left of the 6mm post.
The photo to the left shows what happened when a sterling silver setting was co-fired with PMC in the BRONZclay firing pan. On the first firing, the binder burned out but the silver clay did not sinter. On the second firing, the silver clay sintered, but attempted to alloy with the sterling. Incidentally, the blue stone is a Tanzanite CZ. Normally this stone can only be fired to 1110F for 10 minutes, but in the oxygen-reduced atmosphere of the activated carbon, this color survives beautifully.
This photo shows the back side of the same piece. Notice the large gap where post comes through the clay. The bronze did not sinter tightly around the post, it only attempted to absorb the silver.
Carbon crumbs can get in between a gemstone and the edge of the setting. A small piece of fiber paper can be laid on top of the stone to protect it from carbon dust. Use a small piece to avoid creating air pockets in the carbon.
Sanding & Refining
BRONZclay is very easy to sand, file, shape and carve when dry, and much more difficult in the fired stage. Do all the work you possibly can before the clay is fired. Smooth out with sandpaper. The clay can even be "pre-polished" and burnished.
BRONZclay is wonderful to carve. Use miniature carving tools, wax carving tools, ball burnishers, needle tools, etc. I like using diamond tips of various shapes to "rub" away areas. They can be used to carve by rubbing. Use them in a hand-chuck rather than a rotary tool. BRONZclay is so soft that no power is needed to "power carve" it. Save the chips from carving to rehydrate or use as embellishments.
Bronze clay is easy to solder, however, pickling will dissolve the tin from the surface, making it look like copper. Be prepared for a copper colored surface if you pickle. In this way you can end up with both copper and bronze clay from one material.
Polishing and Patina
BRONZclay can be worn right out of the kiln with no polishing or finishing at all and people love the look. The beautiful peacock colors that come from the coal-based carbon are stunning and surprisingly durable, but BRONZclay is a true bronze when fired. It can be polished and patinated just like any other bronze. It can be oxidized by heat or by chemical. It can be colored with a wide variety of patinas and polished to look like gold, adding almost limitless possibilities for creating. BRONZclay can also made to look like copper just by pickling. The mild acid of a pickling solution dissolves the tin from the surface of the metal; similar to when silver is pickled, leaving an enriched copper surface.
Copper and the Green Finger
Copper is famous for it's beautiful green patina, but most of us prefer that patina on architecture and sculpture, not our fingers. BRONZclay is composed of 85% copper. Most peoples' skin oils will react copper and oxidize very quickly, leaving a green stain around the finger (or wrist if it's a cuff bracelet). Where there is sweat, there will be oxidation. There are a few approaches to this problem. You can avoid making rings, accept the patina on your skin, wear bronze rings and cuffs only long enough that they don't cause a reaction, use a sterling silver, silver or gold insert to keep skin from contacting the bronze, or silver plate the item. For a cuff bracelet, snakeskin, leather or Ultrasuede could be used as a liner.
If your clay starts to show moldy looking green/black patches or spots, this is oxidation. If it's just lightly darkened, just knead it into the ball. If its heavy or really gross, scrape it off and discard it. The rest of the lump will be fine. Use Lavender water and keep your clay tightly wrapped to avoid oxidation. A little bit of oxidation on the clay won't hurt the firing process.