LOSS WAX PROCESS
Mold Making- This is creating a mold of the original model or sculpture. The rigid outer molds contain the softer inner mold, which is the exact negative of the original model. Inner molds are usually made of rubber or silicone, which is supported by the outer mold. The outer mold can be made from plaster, but can also be made of fiberglass or other materials.
Wax Making and Rework- Once the mold is finished, molten wax painted into it and sloshed around until an even coat covers the inner surface of the mold. This is repeated until the desired thickness is reached. This hollow wax copy of the original model is removed from the mold and reworked. Reworking is fixing any imperfections in the wax piece till the wax looks like the original piece.
Gating- The wax piece is attached with a tubing structure of wax called a gating system. The carefully planned gating system will eventually provide paths for molten casting material to flow and air to escape. This gating system doesn't have to be hollow, as it will be melted out later in the process.
Shell Building- The gated wax piece is dipped into a slurry of silica, then into sand creating a ceramic shell around the wax piece. This shell is allowed to dry, and the process is repeated until the ceramic coating reaches a desired thickness around the entire piece.
Burnout- The ceramic shell-coated piece is placed in a kiln, whose heat hardens the silica coatings into a shell, and the wax melts and runs out. Now all that remains of the original artwork is the negative space, formerly occupied by the wax, inside the hardened ceramic shell.
Pouring- The shell is reheated in the kiln to bring up to temperature. Once up to temperature the ceramic shell is buried in sand. Metal is melted in a crucible in a furnace, and then poured carefully into the shell. The filled shells are allowed to cool.
Knock out- Once cooled the shell is hammered or sand-blasted away, releasing the rough casting. The gating system, which is also faithfully recreated in metal, is cut off, to be reused in another casting.
Finishing- The casting is worked until the telltale signs of the casting process are removed, and the casting now looks like the original model.
Patina- Various chemical compounds are applied with heat to the surface of the piece to reach a desired color is achieved.