What is Bronze?One of the comments that I have commonly heard is goes something like this, “Wow, I really like this but it is way too expensive, it costs as much as my car”. How do I respond? The first thing I usually do is to say you are right, bronze is expensive. The next thing I do, if my audience seems receptive, is to begin the process of explaining why bronzes are always priced so high. Let me try to describe this process here. The bronze that a consumer sees is the final product of many separate, expensive and time consuming steps. The first step is the creation of the original artwork.
The Original ArtworkAfter coming up with an idea of what I am interested in doing I make several rough sketches of what I would like the final product to look like. If my idea involves an actual living or extinct animal I spend some time here doing research. When creating the piece Centaur Warrior, I photographed and video taped horses standing, walking and running. I researched the anatomy and musculature of a horse. When creating the Plesiosaur I read and consulted with leading paleontologist in the field to make sure the details were as correct as we can make them with the knowledge we have. I then create a metal armature. The armature is a framework for the soft clay or wax that I will layer and sculpt into a finished piece. This is for me one of the best parts of creating bronze sculptures. The wire armature lets me create something airy, light and full of movement and energy. The clay or wax coating lets me add detail over this light support. Neither product is all that great in itself but taken together something really neat can be created. The time for this process varies with the piece but it is not unusual to spend weeks or even months on an original sculpture. One problem with this combination of materials is that it is not permanent, clay pieces are quite fragile and are easily damaged. Bronze is tough and extremely durable material, so now to turn the clay piece in to bronze.
Making Molds and CastsThe clay can not be directly turned into bronze, there are several intermediate steps, and the first of these steps is making a mold. A mold is made of the clay original, usually out of some type of rubber, which is poured around the original as a liquid and then allowed to harden. This rubber can be expensive. A five-gallon bucket may cost around 600.00 dollars. I am constantly amazed at the detail this rubber can pick up; fine markings on a sculpture down to faint fingerprints are faithfully reproduced. The trick to this process is to make a mold that is easy to remove without destroying your sculpture. Molds can be very simple one-piece molds of relatively flat two-dimensional surfaces with little relief. They can also be very complicated multiple part molds surrounded by multiple part mother molds. Generally the more complicated the original the more complicated the mold. My large winged dragon sculpture, Out of the Blue, required numerous molds totaling about 16 separate pieces, in this sculpture the original actually had to be cut into smaller pieces and have molds made of these parts. After the molds have been successfully poured they are removed from the original and cleaned. They are now ready to create a wax cast of the original sculpture.
In this step wax is melted and poured in to the molds prepared earlier. This is an important step; an artist who invests time and materials into getting a sculpture to this stage does not want a bad wax cast. Care is taken to ensure any air bubbles, mold seams or other blemishes on the surface of the cast are removed. A well-prepared mold helps but there are always some details that need cleaning up. If the mold had many parts this is one stage in which many of these are reassembled.
Now, off to the foundry.All true cast bronze is still created using some variation of the traditional technique of lost wax casting. In this process the wax cast is encased in ceramic shell. Dipping the wax into a resin compound and then into fine sand letting it dry and then repeating the process many times creates the ceramic shell. When completely dry this is put into a kiln and baked to melt and drive out the wax. This leaves a hollow shell with a cavity inside that looks exactly like the original clay. Wax pieces had been added prior to creating the ceramic shell, which when melted away leave a hole in the shell for molten bronze to be poured in and air to come out. The bronze is melted from ingots at more than 2000 degrees Fahrenheit. When the crucible containing this bronze is taken out of the furnace it glows like the sun. It is very impressive! The molten bronze is poured into the shell filling up the smallest cavities. At these temperatures it flows like water.
Cleanup and ChasingAfter the bronze has been allowed to cool, on a big piece something that may take a day, the ceramic shell is broken off of the cast bronze. It pretty much just shatters when lightly struck. The bronze right out of the shell is not a pretty site. It has to be cleaned and chased to remove any imperfection. If the sculpture was not cast in all one piece the separate parts are now welded together with additional attention being paid to chase and clean up the weld joints. It still does not look like a finished piece but it has come a long way. It is now sand blasted to remove any remaining shell or chemical residue from the casting process.
PatinaAll bronzes must have some type of finish. The finish can be applied at the foundry or can slowly form over the surface of the bronze. This finish is called the patina. Patinas vary widely in color from black to blue to green to red to brown to white. What all patinas have in common is that they are chemically a part of the sculpture’s surface, they are never a painted coating. Patinas are often applied hot. To do this the bronze is heated back up to about 400-500 degrees Fahrenheit and various chemical solutions sprayed or brushed on. These react with the bronze to form the durable patina.
MountingThe bronze is now almost done. The final step is to mount the sculpture on some type of complimentary base. Mounting material can be some type of stone such as marble or granite; it may also be a fine wood like cherry, walnut, maple or oak. Bases are often a combination of material chosen to display and accentuate the sculpture.
DurabilityTrue bronzes are made of tough durable pure metal. There are cheaper versions of bronze sculpture. Some of these go by name cold cast bronze. This is nothing more than bronze powder mixed with a resin. They often have a piece of metal inside to give them the heavy feel of real bronze. When dropped they are easily marred in a fire they would burn or melt. They are not true bronzes. A true bronze sculpture will virtually last forever. Bronzes have been recovered intact from ship wrecks and the buried ruins of ancient civilizations. True bronzes weather raging fires and might need nothing more than a little sandblasting and patina to be as good as new. A cast bronze will last for thousands of years. A beautiful bronze sculpture can add excitement and joy for generations.
Limited Additions and CostCreating bronze sculpture is very expensive. Foundry charges alone can be more than half the value of a finished artwork. This does not even include the initial investment by the artist in both time and materials. Much of an artist expense goes into many of the steps before the artwork ever makes it to the foundry. Making copies can spread this cost out. Most of the bronzes sold are limited editions. This means that the artist decides ahead of time how many copies he or she is going to make. An open addition means that the artist reserves the right to make as many copies as he wants. Generally the more copies made the less expensive an artwork might be while the fewer copies the greater the expense to the consumer. In my descriptions of my sculpture I always list whether or not the sculpture is open or not and if limited how many I plan on making. The molds will be destroyed when the last cast has been made. The number of the addition is on each piece.
Pick out a sculpture, take it home and enjoy!