The waxes have been sprued and dipped in ceramic shell. The sprues are essentially a wax structure that will create a path for the iron to get into the mold and the gases to escape out of the mold. The shell is a series of layers of sand and ceramic slurry. The sprued piece is dipped in both in turn and allowed to dry until sufficient layers are built up. The top is then cut off (exposing the opening of the cup on top and the tops of the vents), the wax is all melted out of the shell while the ceramic is fired. It will turn white in the firing and is then ready to pour iron into.