To Create A Bronze Sculpture

At times our jobs become just that; a job, work, and we may look past what we are actually doing and its importance in our lives or to society. I must admit that at times this   happens to me. Every now and then we give tours to groups or individuals and show the process of casting a bronze sculpture. By the end of a tour people are fascinated by the process and even make comments to our foundry workers how lucky they must feel to be involved in creating a sculpture. It’s at these times, by looking at what we do through someone else’s eyes that the magic of our “job” suddenly appears and we step back and say, “You’re right! This is cool!” In this light, I want to discuss the wonderful process of making a bronze sculpture.

First thing is the idea or inspiration; where does it come from and what am I going to do with it when it strikes? After having my own children, I would watch how they play and interact with each other and their environments. A great deal of my sculptures, and some of my most successful pieces, came about from observing my children. Other inspirations come from reading, or catching a movie or television show about an individual or topic. For this discussion I will relate about a piece I titled Messenger of Light.

I had an experience take place that was something that I needed just at the very moment when I needed it. It was almost like an angel was right there handing it to me. That image came to my mind- an angel offering a blessing she holds in her outstretched, cupped hands. I could picture it and quickly did a sketch in clay. From my little clay sketch, I resolved the design issues and went to work with my armature, bending and shaping the wires to fit my design. The armature will act as a skeleton as I add clay and will give the sculpture stability. Many long, sometimes tedious hours are spent on sculpting the piece until I feel it is complete. Once I feel it is finished I turn it over to the foundry crew to cast it in bronze.

To create a bronze a mold must be made of the sculpture. Silicone rubber is used for this process. Many coats of rubber will be applied to the clay with the first coat being very thin so it can capture all the detail of the clay, even my fingerprints will be detectable. After a number of gradually thicker coats of rubber have been applied, dried and set up, a plaster mold is made around the rubber mold. This “mother mold” will help to keep the rubber mold closed properly so we can pour wax into the mold. We remove the mold and then reuse the clay for another sculpture.

The mold is taken to the wax room where hot wax is poured slowly into the mold; the mold is rotated to ensure complete coverage, and then dumped out. This process is repeated a couple more times so the wax is about an eighth of an inch thick. After it has cooled sufficiently it is removed from the mold and given to a waxchaser whose job it is to clean up the seams and fix any imperfections or fill in any bubbles that may have occurred when being poured. The waxchaser will also attach wax sticks called sprues and a wax cup to the piece that will act as a gating system for the bronze to flow through.

The wax is then taken to the slurry room where it is submerged into a sort of liquid ceramic called slurry and then sand is added to it to start creating a shell. Six or seven dips later (with sand added after each dip) the dried shell has the bottom of the cup drilled out and is taken to an autoclave to melt the wax out of the shell. This hollow shell is now an exact replica of the original clay and will be a mold to pour the molten bronze into.

            The hollow shells are placed in a furnace and heated to approximately 1,900 degrees. The bronze, which comes in ingots, are placed in a crucible that is lowered into a furnace and is heated to 2,100 degrees. The foundry workers dress in their gear to avoid the excessive hear, pull the shells out of the furnace then lift the crucible out of the furnace and pour the molten bronze into the shells. After a short while the shells are taken to the chipping room where this shell is chipped of and cleaned up.

            In the metal room the different pieces of the sculpture are welded together and different grinder bits are used to both grind down the welds and to fix the texture to make it look like the original texture that the artist created in clay. These metal workers, as well as the waxchasers, are artists in and of themselves. Once they get it all put together and looking good, the bronze is sandblasted and ready for a patina.

            A bronze can really be any color you like. A classic brown patina is achieved by blackening the whole surface with liver of sulfur, scrubbing it back with and abrasive pad, rinsing as it is scrubbed. This will accentuate the texture by leaving the blackness in the recessed parts of the sculpture. The bronze is then heated with a torch and ferric nitrate is applied followed by a lacquer or wax to seal the patina. For the Messenger of Light sculpture, I wanted a more ethereal feel so the patina is a butterscotch color. This is accomplished by a mixture of ferric nitrate and titanium and applied with a brush while the sculpture is being heated with a torch. Again, it will be sealed with lacquer and wax.

            The casting process is very labor intensive with many hours devoted to create each sculpture. Understandably if you are doing the same thing day after day the luster of your efforts may wane, but taken as a whole, the casting process is like another sculpture I created showing 5 hands, each hand gripping the wrist of another, titled Synergy- the whole being greater than the sum of its parts. There is also such a rewarding feeling to see the fruits of a thought or feeling now as a 3 dimensional tactile entity. Yeah, looking at it from the outside in, it really is pretty cool!