The Bronze Process

The lost wax bronze casting process has a very long history in art; going back to ancient Greece when bronze sculptures were first made. The process is very long, and involves a lot of techniques and expensive equipment, so most artists go to a foundry to have their work cast.  I work part time at Schaefer Art Bronze in Arlington back in Texas. Right now while I am at the Armory I have been working on a new bronze piece. I am learning to do all the steps of the process myself. First, I started with an original sculpture.

Once this oil clay sculpture is complete it is ready for cutting and molding. a piece like this has to be cut into multiple sections to be molded because the forms are too complex to cast in one piece.

Each rhino was cut off of the base at the ankles, leaving the feet attached to the base. The rhinos were then cut in half to simplify the forms and make a nice open space on each half to pour the wax into the mold.

The base will be a  simple one piece mold. All the parts of the sculpture were set up on boards that left a 2-3 inch boarder all the way around the piece.

I used thin metal sheet to shim the seam line between the two halves of each rhino. This will be the divider between the rubber that will make it a two piece mold. Plastic keys were used to create a locking mechanism between the pieces of rubber. The pieces are all sealed with a layer of spray shellac and a layer of universal mold release. This will keep the rubber from sticking to the shims or to the oil clay.

Once the shimming was complete I used urethane rubber to make the molds of each rhino. Urethane rubber or silicone rubber is usually used to mold pieces for bronze because they release the waxes very well. Urethane molds can also be used to cast resin and some plastics. I started these molds by painting on a thin layer of the mixed rubber and once this was tacky, I was able to continue adding layers of rubber until thick enough in all areas.

When the rubber molds were completely set, the edges were trimmed and the rubber was sprayed with a few coats of epoxy parfilm. Since these molds were being made with a resin mother mold, epoxy parfilm keeps the resin from sticking to the rubber.

To make a mother mold, resin is mixed and poured out on cardboard. Fiber glass sheets are cut up into squares and patted into the resin until soaked. These are laid on the rubber and built up in several layers.

A mother mold is a hard shell that holds the rubber in the correct shape when you pour waxes. The fiber glass acts as a weave holding the resin together. This method makes a strong and lightweight mother mold.

When the resin has set the molds are ground with an angle grinder on the edges and the mother mold is pulled away from the rubber.

Once the molds were cleaned, and bolted together tightly the waxes were poured.

The waxes are removed from the molds and chased. This means that I sculpt on the wax to restore original textures and small details that were distorted in the mold and melt down seams from where the two halves met.

Because the base of this piece is so large it is cut in half. Wax rods called sprues are used in gating the waxes. Gating provides channels for the bronze metal to flow quickly and evenly to all parts of the sculpture.

The rhinos are also cast in two halves on one sprue tree. This will make it easier to dip the pieces in ceramic shell, and make the welding in the metal less difficult to work on.

Ceramic shell is a mixture of fused silica and a binder. The waxes are dipped in this mixture and then covered with fused silica sand.

The piece is dipped in the shell multiple times. The shell dries hard and solid making a negative impression of the inside and outside of each part of the sculpture, acting like a “shell”.

After the shell has dried it is fired in a burnout kiln and the wax is melted out. This firing hardens the shell so that it can then hold the molten bronze.

DSC03867After the bronze is poured and has cooled, the ceramic shell has to be broken off the metal and sandblasted clean.

20130614_154823Once the metal pieces are cast, they have to be lined up and welded. 20130614_141849Welding leaves a thick bead like a seam that then has to be ground down and made to match the texture of the piece.

20130618_114219Once all the pieces are welded together it is sandblasted clean one more time before it is given a patina.

20130619_134507To patina bronze a torch is used to heat the metal so that it can be sprayed with different chemicals. The heat allows the chemicals to react with the metal and create a color on the surface. Brushes and scrubbing pads can be used to create highlights in the patina.

Here is an image of the finished piece!

DSC04580“Clash of the Titans”


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Residency Exhibition and New Work

My residency at the Armory Art Center has come to an end! I had such a great time teaching and making sculptures there!

Here are some images from my residency exhibition opening, along with some close ups of my new work.

DSC04406DSC04412DSC04414DSC04425New Work: The Prehistoric Circus

Elements of the circus in each of my sculptures represent the wonder in discovering prehistoric animals, and their amazing feats of evolution. The brightly colored drapery that adorns the broad back of an ancient giant brings about the impossible idea of a prehistoric circus; a tragic circus lost in time along with the animals themselves. Colors and intricate patterns are fading; the paint peels and wood rots away under heavy feet and wrinkled hide. My sculptures express the joy I find in the animal form while lavish decorations celebrate these creatures as the greatest show on earth.

The Pyramid of Pachyderms



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New Pieces in Process: Saber-toothed Cat and Florida Fossils

Here is an update on some of the new pieces I have been working on at the Armory Art Center this fall. These pieces are still in the works, and all of them are at different stages in the process.

This saber cat was a much larger piece that I fired recently. I reassemble all my larger sculptures on a piece of drywall that is then burned out in the kiln. Drywall will not harm the kiln or the elements in an electric kiln, the paper burns away and the plaster moves with the piece and remains through the firing. This way I don’t have to lift the heavy or fragile piece to get it into the kiln.

First,  I raise the lift to the level of my work table and put down a little grog, this rough fired clay material acts like small ball berrings and helps the heavy sculpture slide onto the lift easily.

With the lift in place and lowered to the height of the kiln floor I can slide the drywall and the piece off the lift and into the kiln. The excess drywall is cut away after the piece is positioned. The saber cat fired for about 4 days in a small gas kiln. I always load large work at the leatherhard state so that the clay is less fragile, and any breaks that happen during loading are easy to fix.

After the piece is bisqued, I will add non ceramic elements. Since I am doing a cold finish, paints, stains, ect. on these new sculptures they won’t be needing a second firing for glazes. This saber cat will be wearing an antique leather collar. I carved a space for the collar in the wet clay, usually a little wider than necessary to account for the clay shrinking. Once the collar is in place I use Bray-poxy to sculpt additional hair that will help it look more like part of the piece. Bray-poxy is a two part epoxy putty that can be sculpted with and added to fired clay. It dries as hard as bisque clay and can be painted to match any surface. It can be purchased over the phone from the Archie Bray Foundation.

I have been experiementing with new techniques for armatures and scale as well. Here, you can see a poster in the background. This is an image I took of a maquette for this piece and then enlarged to the size I wanted the final sculpture to be. This is a great aid for sculpting as well as figuring out what size armature rods will be needed. I usually use galvanized stell pipe as an armature along with dowel rods. I am also using multiple dowel pieces taped together with electrical tape for legs and extremities. These are flexible and act as a movable joint even when clay is put over them. This allows me to change the gesture of the legs more easily.

This prehistoric deer, a blastomeryx, is life size at about 24 inches long. These types of small deer were found in a fossil pit near Tampa. Many of the modern deer in Florida are descendants of deer like this one. These deer ranged in size from a rabbit to a small dog. Their living relatives the key deer that live in the  Florida Keys. The small size of these early mammals often helped them survive climate changes and atmospheric changes that killed off much larger animals.


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Welcome to Florida: The Armory Art Center Experience


This year I was accepted as an artist in residence at the Armory Art Center in West Palm Beach, Florida. Tibbers and I made it through the 20 hour drive from Dallas and I am now making work in a great studio with lots of other artists.

This year the Armory accepted six resident artists from all over the country working in ceramics, sculpture, jewelry, and painting. I will be a sculpture resident for the next 8 months. I plan to work in both clay and bronze and use non-ceramic materials on my pieces while I am here. The Armory provides a generous stipend to residents and pays artists to teach classes during their residency as well. Check out the course catalog. I am teaching classes in figure sculpture, animal sculpture, and bronze sculpture.

The first project that I started at the Armory was an original sculpture for a large bronze. I used a hard foam shape as the base and covered this with a layer of clay. The two rods have been hammered down into this foam base to hold up the rhinos.

On top of these rods I use electrical tape and dowel rods to hold up the animals and the weight of solid oil based clay.

I smear the oil clay over this structure and begin to form the rhinos. This pair of Arsinotherium, an animal that existed in Ethiopia 30 million years ago, will be charging one another similar to modern day rhinos.


With the musculature and gestures roughed out, these rhinos are ready for detail. Unlike my water based clay sculptures, these pieces do not have to be hollowed out, they will be molded as part of the bronze casting process and then the clay will be recycled, not fired.

Here is the finished oil clay sculpture with all the details and texture. There are some real rocks embedded in the base because these can be cast with the molds.

When this piece is molded, a wax version will be cast so that it can become a bronze. Check out the studio blog later on for the rest of this process! Subscribe to this blog to keep up with all the pieces I make at the Armory Art Center during my residency!


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New Pieces: Chronos

One of my most recent pieces has been based on my research trip to the Paris Natural History Museum. This is the 20ft. tall giant ground sloth, or Megatherium that I studied there. Seeing this complete skeleton up close gave me a really good idea of how to go about sculpting this strange animal.

While there were once many different species of ground sloth that roamed North and South America, Megatherium was the largest. Living as far back as 2 million years ago, these sloths were not as slow as their living relatives the tree sloth. They could move quickly and because of their size they had few predators. These animals were omnivores as well and are believed to have scavenged for meat as well as vegetation.

Megatherium also had very long claws on its front and hind feet. It used these in self defense and to scrape leaves from the large tree branches. The giant sloth had feet and forepaws that rolled outward when it walked so that these long claws were turned upward and protected.

I started by doing some studies of the giant sloth’s anatomy and making a small version of the larger piece I wanted to make. This maquette often helps me make decisions about gesture and expression before I begin work on the larger piece.

This piece was about 2x the size of the maquette. Making a scale maquette helps me get proportions more accurate on the larger one. I try to multiply scale by 2 with most of my pieces to keep things simple. Above is the solid rough start of the large piece. I used a 24” h galvanized pipe with threading that screwed into a metal base attached to the board. This helped the clay have something to stick to. The weight of larger solid pieces can often make them collapse or sink in if the clay is wet enough, so even a simple armature can help a lot.

Here, more of the details have been roughed out, and all the anatomy and musculature is finished. This is usually the point where I hollow out a piece. This way no detail is lost or needs to be redone because of the hollowing process. I will leave making the claws until the very end because they will dry quickly and be the most delicate part of the piece.

I start by cutting off a small section first. Usually the head needs at least two sections so that the snout can be hollowed out. I hollow out the nose and then cut off and hollow out the head. After this I reattach the sections and continue hollowing the rest of the body the same way.

Hollowing larger body sections can be a bit daunting. I try and keep the wall thickness of my pieces between 1/2 and 1/4 inches. I start by drawing a line around where I want to start to be more careful with my carving. Once this line is reached I use a rib and smaller loop tools to make the walls as thin, even, and compressed as possible. This is what will hold up the piece with no other internal structures.

As I cut each section with the wire tool I am able to lift it right off the armature pole in the center. I always make sure that the piece is completely leatherhard before hollowing. This helps keep the walls from moving as I hollow, so the piece fits back together well. I keep areas like feet, tail and arms wrapped up as I hollow so that they don’t get too dry.

I start reattaching the  hollowed sections of the body on a new board. For large pieces I often cut a piece of drywall to fit the piece and once it is reassembled I fire it on the drywall. The paper burns out but the plaster on the inside stays and provides support for the sculpture during the loading and the firing. Here, the hollow bottom and middle sections have been reattached first, and the rest of the piece stacks on, much like a handbuilt pot.

Here you can see the thinness of the walls and the lack of internal supports. The piece will support itself if the walls are compressed and even. I put the arms on last because they add weight to the front of the piece. When this sculpture was solid clay it weighed around 200 lbs., after hollowing it weighs around 45lbs.

I make sure to slip and score each section to attach them. This way the slip goes in between the scratch marks in each side of the sections and acts like glue. I made a small support for the belly of this piece using a solid piece of clay that I poke holes in so it drys quickly. This piece was front heavy, and the support at the belly kept it from leaning forward during the firing. I also pre-cut a groove for the leather strap on the muzzle of this piece. This gives me a place to glue in non-ceramic materials, and makes it seem as though the leather strap is very tight against the animal’s flesh.

Here, the piece is finished and ready for firing. The claws were each sculpted individually and then slipped and scored into holes in each of the toes and fingers. More hair texture was added as well. I then load the whole piece, drywall and all, into the kiln while it is still leatherhard. This way if anything is to break during the move or loading it is still fixable. I let the piece dry out for a few days with the kiln off and then do a slow firing, about 3-4 days depending on how dry the piece is.

Oh no! When this piece came out of the kiln parts of the head had blown off! This can happen for any number of reasons, but in this case I think the clay on top was wetter than the clay underneath, or there were air pockets between the layers of clay. Lack of compression of the clay when solid building or differences in the dryness of the clay can cause little blow outs like this one. They are easily fixed! I used 5 min. epoxy to glue the larger pieces with the ears back on, but the rest of the pieces were too small to glue.

For filling large areas of a blow out or cracks in sculpture I use East Valley Epoxy, which can be purchased from the Archie Bray Foundation in Montana. This excellent epoxy paste works and looks just like clay! It also drys just as hard as fired clay. It can be smoothed with water and worked in the hands like clay. Sculpting tools can be used on it to perfectly match any texture, and it can be sanded smooth when dry. East Valley Epoxy can also be colored with ceramic pigments, or painted to match any glaze surface. There are also cheaper alternatives that can work for filling large spaces, plumbers putty, bondo, pc-7 and pc-11 are all great materials that are sold at any hardware store. They all have different solvents and durability depending on what they are needed for.

For the surface of this piece I used flat interior house paint. I loved working with this cold finish and not having to worry about how glazes might turn out. The finished piece here also has the leather strap and twine attached.

This piece was inspired by the dancing sloth bears in India. The leather strap and twine is a common harness for these seemingly dangerous animals. Similarly, the giant sloth with its long claws seems more than an match for such a feeble attempt to control it.

In Greek mythology, Chronos is the personification of time. I felt that the giant sloth was  like this as well. He seems an ancient giant, strange and unknown, from a time when all nature was untamed and unrestricted.

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Porcleain Menagerie

Check out my new Etsy Shop! Porcelain Menagerie is a line of animal figurines that I designed inspired by my trips to European porcelain factories. They are all made from original sculptures that I mold and assemble myself.

You can also visit the studio blog for Porcelain Menagerie and see how these pieces are made!

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The New Studio

Since graduating from KCAI I have been working on fixing up my mom’s studio. Now there is room for both of us (and everything is much more organized….). I really love the space, despite the lack of ac/heat. It is great to be so close to the nature and animals that I grew up with.

These are the shelves tools and glaze. We had so many of each tool I decided to just put each kind of tool into a separate tub. This way its easy to find and prepare tool sets for workshops or demonstrations.

On the other side of the studio, my mom works on figurative sculpture and functional pottery. We have a working antique cast iron wood stove that was great for heating the studio in a Texas winter. We have one barrel kiln hooked up right now and a kiln patio with a gas, centenary arch, wood fire kilns, and raku.

These casting tables are where I make plaster molds. They have slate tops that the plaster doesn’t stick to. And of course, my studio dog, Tibbers, who lends a paw when I need a live model.

Here are some images of recent work in process.

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