"30,000 Miles" Bronze Casting
Bronze casting of my old motorcycle boots, worn on four cross-country trips.
30,000 miles - The Lost Wax Casting Process
The Lost Wax Casting Process Explained
Preparing the boots for the rubber mold
Beginning to apply rubber in layers, after mixing parts A and B. Room temperature vulcanization.
Many layers of rubber, hardened after two days. Preparing to cover the rubber mold in a plaster shell.
Applying the plaster shell in two halves.
Removing the plaster shell. After cutting a seam in the rubber mold, extracting the original boots. Cleaning and smoothing the plaster to prepare for the wax pour.
Pouring and sloshing hot wax multiple times to build up 1/4" thick layer inside of mold. Carefully removing the cooled wax boot from the mold.
The original boots with the was replica. Fabricating the inside straps. Three wax copies.
Tools for wax clean-up work. Soldering iron with rheostat to control its temperature. Modifying tools to fit the specific needs of the project. Studio wax working set-up.
Detailed wax preparation. Filling air bubbles and other small defects with green wax. Scraping to create texture. Working outside when possible (and listening to lots of NPR).
Attaching the boots to a wax spruce, which will channel the molten bronze. A hole called a door is cut to allow ceramic slurry to enter and exit the sprued wax.
Dipping the waxes in liquid ceramic shell (slurry), the first of multiple dips. The ceramic shell will be strong enough to withstand thermal shock of thousand degree temperature differences. It is the same material used on the outside of the space shuttle to protect it during re-entry into Earth's atmosphere.
Other waxes in different times of their dipping cycles hanging on the drying rack. Sprinkling the slurry area with refined silica sand. Drying the ceramic shell with forced air.
Melting bronze blocks in the furnace to prepare for the pour. Pre-heating the ceramic shells with propane. Checking the temperature of the liquid metal - it should reach 2100 degrees Fahrenheit.
Scraping away the impurities that rise to the top of the liquid bronze. Removing the crucible from the furnace and navigating it to the ceramic molds.
Pouring the bronze.
Cooling the shells with water.
Replacing the crucible.
Returning the crucible to the furnace.
Bright Foundry artists: Raymond Graf, Matt Weir, Brad White, Jep Bright, Scott Boyer
Breaking the cooled bronze out of the ceramic shell. Chipping the shell from the insides of the boots.
Removing the sprue with a plasma cutter. Sandblasting away the remains of the shell.
Grinding away the remains of the sprue. Liver of sulphur will be used in the final patina. It is used now to reveal imperfections and to represent the final look.
Replicating leather textures in the bronze using sandpaper and other abrasives.
Grinding the edges of the plate and tig welding it back into the bottom of the boot.
Tig welding and detailed grinding.
Stamping identification into the metal. Removing "knurdles" (bits of bronze left over from the casting process) with a Dremel tool. Inspecting flashing due to a small crack in the ceramic shell.
Filling and cleaning up "dropouts" - places where the metal cooled before reaching the edge of the shell.
Using heat while applying the base patina of liver, building up dark tone in layers. Not pictured: The final sandblasting before patina.
Using water and scrub pads to remove liver off the surface of the bronze. What remains in the low points will add contrast.
Applying ferric nitrate, the final layer of patina. The metal must be hot enough to force the liquid to evaporate quickly before it drips.
Coating the still warm metal with paste wax.
Raymond Graf and Matt Weir at the Bright Foundry. Sarah with finished boots.