I was at LTUE in March of 2017, when I bumped into Isaac Stewart. He asked if I might be interested in sculpting the logo for Dragonsteel Entertainment, Brandon Sanderson's production company. I of course was super interested. I had met Brandon several times before at various writing conferences. In fact, he was the first professional author I had ever met. I ran into him and David Farland (Wolverton) at a Barnes & Noble in Layton, Utah many years ago when he was on his original Mistborn tour.
Even though I was acquainted, I had never actually read any of Brandon's books. So after taking on the project, I decided I had better get started. I don't have time to do a ton of reading as I own a software company, and I can only sculpt in my spare time when I am not busy with my family. But I listen to audible on my way to and from my office each day. So I purchased the original Mistborn trilogy and started listening.
I didn't have any idea what I was in for. I loved all three Mistborn books. I liked how thought provoking they were, and how they delved into faith and religion. The books became more and more epic as they went, and I knew Brandon's books would now rank among my favorites of all time.
Of course I went on to read the next trilogy with Wax and Wayne. Awesome as well. Loved every bit. Now I have gone on to the Stormlight Archive, and the story of Kaladin, Dalinar Kholin, Jasnah and Shallan. I got hooked on that series as well, and am now listening to Oathbringer.
After looking into Brandon's novels and becoming a full fledged fan of his work, I felt much more qualified to capture the spirit of the Dragonsteel logo. This sculpture came together quickly because it was in relief (flat). But there ended up being a ton of detail at the end. Also, this was the first time I had built in an LED backlight, so that was super awesome.
And I would be ungrateful if I didn't thank Brandon, Emily, Issac, Kara, Adam and the rest of the folks at Dragonsteel. They were so gracious and hospitable during this process. What great people.
From Clay to Bronze
I'll go through the steps to create the Dragonsteel Logo Sculpture one by one so that you can appreciate the work that goes into a lost wax bronze casting. As you'll see, there are many people involved that use expensive and at times, dangerous equipment. You may click on the images below for a larger view and description.
Step 1: Design
I was given a reference design for the Dragonsteel logo. I printed this out and traced the outlines in pencil. I played around a bit with the design. Then I sculpted a 1 hour mockup, just as a proof of concept. And yes, that's my iPad Pro underneath. It makes a nice sculpture stand in a pinch.
Step 2: Roughing In the Form
Because this sculpture ended up being done in relief (flat), it didn't require any armature. I traced the logo in Adobe Illustrator, then printed it out at the right size. Then I pressed the clay directly on the paper. For this first version of the sculpture, I matched the logo exactly. If it had stayed like this, it would have been anchored to the wall in separate pieces.
Step 3: Detailing the Form
I worked with Isaac at Dragonsteel to get a final design. Then I detailed it heavily. In the second photo, I took off the horn to better get at the sword details.
Step 4: Flexible Silicone Mold
After the clay sculpture is complete, it is ready to be molded. The first step in molding is to apply a flexible silicone rubber mold to capture all the details. During this stage, the strategy for molding is agreed upon and if the sculpture needs to be cut apart, it is done here. Molding a clay sculpture typically ruins it, so for this reason most sculptors contract this out to someone who does it for a living. If you have one shot to get it right, you make the most of it.
Step 5: Rigid Plaster Mold
The flexible rubber mold is too "bendy" to facilitate a proper cast, so it needs a rigid support structure to hold the general form. Plaster is mixed with fiberglass for reinforcement and applied to the silicone rubber mold to make a mother mold. The two molds together are capable of reproducing the general form and fine detail of the sculpture.
Step 6: Wax Casting
Molten bronze is over 2200 degrees Fahrenheit, and would melt the silicone mold instantly. For this reason, we need to make a one-time use ceramic mold that can take the heat. Bronze sculptures are typically not solid. Not only is the bronze metal expensive, it is heavy. So a wax casting is made first by pouring in wax and swirling it around and dumping it out over and over again until the sculpture is between 1/8 inch and 1/4 inch thick. This will be the final thickness of the bronze.
Step 7: Preparing for the Ceramic Mold
In order to take a wax casting and prepare it for the ceramic slurry molding, you must first clean it up and fix any blemishes that may have arisen during the wax casting process. This is called wax chasing. Sometimes parts that were molded separately can be joined together in wax, and sometimes parts that were cast intact must be cut into or broken apart in order for the ceramic mold to work properly. After that, wax rods called sprues must be attached to form the channels that the molten bronze will flow through during the bronze casting phase.
Step 8: Ceramic Slurry Molding
The sculpture is dipped into a ceramic slurry to create a hard, durable shell. This shell will serve as the mold for the molten bronze once the wax has been melted out. The first slurry is very fine and capable of accepting all the detail captured in the wax. It is then coated several more times in progressively coarser and thicker slurry producing a mold strong enough for casting.
Step 9: Preheating the Mold/Melting the Wax
The finished molds are then placed in a high pressure oven called an autoclave. There the high temperature and pressure melts the wax. At over 1800 degrees, any wax that might be trapped in the mold is incinerated. Now that the wax is gone or "lost", the mold bakes in the heat ant pressure and is fully prepared for bronze casting.
Step 10: Bronze Casting
Silicon Bronze is heated to about 2250 degrees Fahrenheit. At that temperature, the molten bronze is hot enough for its radiant heat to melt hair and burn skin, so protective gear must be worn.
Step 11: Chipping/Demolding
The ceramic mold often cracks and begins to fall off in chunks as the bronze cools. However, sometimes it is difficult to remove. A small pneumatic hammer can chip away the ceramic mold without damaging the bronze beneath. Sometimes a sandblaster is used to wear away tiny pieces of the mold that gets stuck in the crevices. Sometimes tiny bits of the ceramic investment is left in areas, like inside the hollow sculpture, where it won't be seen.
Step 12: Metal Chasing/Welding the Parts Together
During metal chasing, the technician will weld together all the pieces and blend in the weld seams using metal tools. He'll also fix any defects in the metal like bubbles or seam marks. Metal sprues will be cut off with a plasma torch and be ground down.
Step 13: Sandblasting
The piece will get a final sandblasting to make sure all the surfaces are free from defects or discoloration. Walnut shells are frequently used as they are hard enough to just barely abrade the surface but not in any material way. It takes off the outer layer of bronze, but won't disfigure the sculpture in any way.
Step 14: Patina
You patina a bronze sculpture by causing its surface to react to chemicals and oxidation. In this case we spray on potash (liver of sulfur or sulfurated potash). This will cause the metal to turn a dingy gray. If it is applied heavy enough, it can help turn the sculpture black. After the potash is applied it is carefully scrubbed back using a mildly abrasive pad. This leaves it darker in the recesses and lighter on the surface. Then the sculpture is heated up to 220 degrees Fahrenheit, and then ferric (ferric nitrate) is applied while hot. This adds a red color to the bronze. The ferric and the potash together will produce colors ranging from gold, orange, brown, and a rich black.