Jewelry casting is not just a method of making jewelry but it is a form of art that has been in existence for thousands of years. Since the time that man learnt to melt metal, artisans have been pouring molten gold into cavities shaped in stones, plaster, sand and cuttlefish bone. The solidified castings were then pried or broken free from the encasements in which they were poured by primitive craftsman who then tooled them into items of adornment.
Jewelry casting has become more dynamic than ever with the advent of high frequency melting and a host of other technologies. Generally, jewelry casting is done through the lost wax process, whereby models created through wax carving, growing or printing are encased in a plaster-like thing which is called investment. This investment is heated to extreme temperatures to incinerate the material which creates an impression of the desired form. The intricate cavity which is created is then filled with molten precious metal.
Gold casting encompasses a wide range of karats and colors, the alloy combinations dictate that each has temperature cycles and processes that are unique to the metal.
Centrifugal Jewelry Casting:
As the name suggests, this method uses the force of centrifuge to create the inertia necessary to throw gold into the hollow cavity left behind. After burnout, the flask is placed in a cradle on a swing arm in direct alignment with a crucible in which gold will be melted. Depending on the equipment and user preference, the crucible will be heated by high frequency, induction or a torch to melt the metal, while the arm is in a cocked position. When the precious metal is at critical temperature, the centrifuge is released and metal is slung from the crucible at high velocity which fills the flask before it rests.
Vacuum casting jewelry:
It is very similar to centrifugal casting. Here also, the molten gold has to be sent with enough thrust into a flask to enable it to funnel it through detailed cavities before cooling. The equipment used for vacuum casting requires the flask to be loaded in a sleeve within a chamber to enable a forcible vacuum to absorb molten metal into the investment as it is being poured.
Precious Metal Castings:
Once the flasks are filled it is necessary to remove the precious metal castings. The hollow impression in plaster, filled with glowing red platinum or gold castings, is lifted from the casting equipment with tongs. Depending on color, carat or metal used, they are quenched in water and left to cool down. When the flasks are cooled down, the investment form is destroyed while the remaining plaster is chipped away, leaving behind a tree containing models as branches. The models are then cut free from the sprue and forwarded to jewelers who then go ahead with jewelry polishing, fabrication and stone setting to transform the casting into the ring that you could flaunt on your finger.