Lost Wax Casting - Steps with Pics

(wax pattern)

1. The figure is carved in solid wax by the sculptor (in this case, M. A. Dabritz). This is called the "wax" or "pattern".



(wax pattern with casting sprues)

2. Sprues (wax "wires") are attached to the pattern. These will burn away to form channels through which the wax leaves the mold and also through which the molten metal enters it.



(ceramic mold made from investment - cut-away view)

3. A ceramic slurry ("investment") is poured around the wax pattern and allowed to harden around it like plaster. This surrounds the pattern completely, the picture shows a cut-away view so you can see what is happening on the inside of the mold.



(ceramic mold after wax evacuation - cut-away view)

4. The wax is "burned out" in a kiln at 1250° F (orange hot), so that it goes up in smoke and leaves its impression in the ceramic. This creates the mold. Hence the term "Lost Wax" because the wax is gone.



(picture is taken with a flash so that you can see the cylinder that used to contain the wax pattern, before it was burned away - now it is the mold into which the metal is forced)

5. Metal is melted and to be forced into the cavity left by the wax.



(unfinished bronze figure with sprues - just out of the mold)

6. The hot mold is plunged into cold water to disintegrate the investment so that the bronze figure(s) can be removed.



(finished piece)

7. The metal figure goes through several finishing and polishing steps to complete it.


Source:
http://www.castofcharacters.com/lostwax.htm