The process of making bronze statues is a common topic of inquiry. Lost Wax casting, often known as the procedure used to create bronze sculptures, dates back millennia. Casting foundries for fine art are now commonplace.
Firebird Bronze Foundry is our own business in Troutdale, Oregon, and we serve artists from all around the world by casting their creations in bronze. Although bronze casting is our speciality at Firebird, we also offer casting in silver, gold, and other precious metals.
Motives Behind the Artwork
The creative process behind each sculpture begins with an idea or concept in our heads. In order to bring your concept for a commissioned sculpture to life, we will investigate its background, meaning, and function.
As such, we approach each commission with an eagerness to learn about the client’s vision and a willingness to listen to and incorporate feedback. Because we share a common artistic vision, we are able to tackle collaborative projects as if we were a single artist.
As our ideas develop, we sketch up visual representations that capture the essence of the final product in terms of its composition, scale, and motions. In the case of commissions, we will first present a rendering for your review and approval before beginning work in clay.
Making Clay Figures
The first step in the creative process is to begin shaping clay using reference materials and models. To ensure the stability of the clay, we shall construct a “bone structure” or armature out of wire or foam.
We used actual measurements to create the monument out of foam, which we then covered with clay. After that, we started the laborious process of sculpting in clay.
This sculpture had to be disassembled into smaller pieces before it could be moulded and cast. The size and complexity of the work determine how many parts it will have. Notches were cut into each piece as a guide for metal joining.
Creating the Form
We poured liquid silicon rubber over each part of the clay artwork to make a mould. The rubber created an exact negative of the sculpture. After the silicon hardened, we used a plaster mother mould to secure the form.
Our moulds are two pieces joined together at their seam, taking inspiration from the “walnut shell” metaphor. The moulds used to cast an edition of sculptures are destroyed once all of the copies have been made. They Bred Good Horses was a one-of-a-kind, therefore the mould was only used once before being put away.
Wax Pattern Making
We heated wax to around 200 degrees Fahrenheit, removed the original clay sculpture, and poured the wax into the rubber mould to create a thin layer. When making wax patterns, the first “hot” layer is used to fill in the small details, and then the form is built up using colder wax (160-180 degrees) to achieve a thickness of 1/8 inch to 3/16 inch.
We pursued the wax patterns by hand to bring out the sculpted intricacies and textures when we removed them from the mould after they had cooled. When there are air bubbles or rough lines in the wax, we utilise chasing to smooth them out with sculpting tools and hot tools.
Designing a Gated System
Once the wax was located and removed, we designed a gating system to create passageways for the bronze to cool in. To join the wax sprues to the wax pattern, we utilised wax.
Designing a gating system involves striking a balance between maximising the flow of liquid metal and allowing gases to escape. A separate gating mechanism is required for each type of wax.
Making a Ceramic Casting Mould
After the wax “tree” with its gates was finished, it was placed inside a ceramic casing. We coated the interior and outside of the hollow waxes on the tree with a ceramic slurry that we dipped it in. We first ceramic-dipped it, then washed it in silica sand. We did this 8-10 times, letting each layer dry in between, to create a dense ceramic shell around the waxes.
Wax Destruction by Fire
After the ceramic moulds had dried and cured, we melted the wax out of them at roughly 800 degrees in the burnout oven at our foundry, earning the name “Lost Wax.” The 1/8″ wax pattern and gating mechanism were burned out, leaving an empty space inside the shells. The shells’ internal cavities and passages transport the molten bronze to various locations.
Casting a Bronze Figure
Typically, the metal pour requires the participation of three of our staff members. While the “deadman” is in charge of keeping the crucible from tipping over, the “lead pour” guides the molten metal to the waiting shells.
The third person makes sure there is no slag or other contaminants floating on top of the molten bronze. Cooperation between the three is crucial to ensuring the pour goes smoothly and without incident.
Joining the Metals
We used images and measurements taken from the original clay sculpture to piece together the new version. We used a TIG welder and a rod made from the same bronze alloy to join the pieces together.
We chased and cleaned the metal in the same way that we did the wax patter to eliminate any surplus and fill any pits. To make it look more cohesive with the rest of the sculpture, we sanded down the weld lines and used carabid-tipped grinders to add surface texture.
We guarantee the best quality welds in terms of both beauty and strength, and we’re proud of the fact that our seam lines are undetectable.
Making Use of Patina
Coloration applied to a bronze sculpture is called a “patina.” It’s caused by a chemical exchange between the bronze’s surface and various metal salts. Using Ferric Nitrate, Liver of Sulphur, and other compounds with varying degrees of heat, we were able to create this reaction.
Different application methods will produce varying effects, from an absolutely uniform coating to a naturally marbled look, since each metal salt, typically a nitrate, responds as a different colour.
Wax is applied to the hot bronze to preserve the patina. Several layers of wax are applied by hand and rubbed to give the sculpture its final lustre after the wax has melted and sealed the pores of the metal.
Putting Up the Statue
It’s always an emotional event to put up a sculpture, and a bronze will last for centuries.
