2.The shell.
The outer mold, made of a very fine highly resistant refractive material, is coated onto the sculpture in increasing layers of thickness and then placed within a holding where a heat resistant liquid clay mixture is poured around it in order to support the piece during casting.

3.Burn-Out.
The mold is placed in the burn-out oven, which bakes the mold and melts away the wax leaving an empty space in its place and ready for the next step: casting.
This is where the term "lost wax" comes from.