Bronze Casting - Step 16
The Shell

Between the finishing and mounting of the wax model, you create a ten layered ceramic mold - or "shell" as it's called - of alumina silcate. The process is by dipping the wax model in a special colloidal suspension of silica and covering it in a layer of sand. You let that layer dry and then built up ten layers of increasing coarseness of sand.

The final layer is simply a final dip in the colloidal suspension to give the shell a smoother surface and to hold the sand in place. Then a final drying and then the "burnout" where the wax is melted and burned - at 1600 degrees Fahrenheit. Again, kids, do NOT try this at home.