Making a Sterling Pendant with Black Opal Part 2

The 900 Degree flask ready for casting
The 900 degree flask is then removed from the kiln. All the wax has melted out of the investment and there is a cavity that is exactly the shape of the wax carving within.
Loading the flask into the casting machine
The hot flask is then placed into this casting machine. The sterling silver is placed in the crucible just to the right of the flask. The lid is closed and the chamber is placed under a vacuum. An inductive current flows through some water-cooled tubes around the crucible and the metal is heated to melting. Once at the proper temperature, the crucible-flask arm begins to spin and the molten silver is flung into the cavity in the flask, filling the void left by the wax carving
The  Supercast vacuum-induction casting machine
This is the casting machine with the cover closed. The molten silver can be seen by looking through the viewport on the top of the machine
The molten silver just prior to casting
This is the view through the viewport of the molten silver just before the arm begins to spin. The silver flows up the crucible and out the spout and into the flask
Quenching the hot flask in water
The flask is allowed to cool a bit, and then it is plunged into cold water to remove most of the investment from the casting
The finished sterling silver casting tree
The remainder of the investment is removed using the ultrasonic cleaner and we are left with a sterling silver representation of the wax model we carved earlier.
Creating the bale from silver wire
The silver pendant is cut from the casting tree and partially finished using rubber abrasive wheels and sandpaper. We also need a way to suspend the pendant from a chain, so a jump ring bale is made from some silver wire. The wire is formed into a circle and then cut using a jeweler's saw
Soldering the jump-ring bale to the pendant
The pendant and jump ring are coated in a solution of boric acid and alcohol which prevents oxidation from the heat, and then a bit of solder is applied and the jump ring is soldered to the pendant using a torch