The Girlfriend's Guide to Jewellery
27: Lost Wax 2011-09-01
This is an ancient casting method that is still widely used to this day. To start, a model is sculpted in wax, finished and polished in every detail.
The wax is carved or sculpted by a specialist who will translate your dream into a one of a kind special design. It is a process that may be used to create one single piece or it may be used to create the master copy for a design destined to be reproduced many times. The wax is placed in a casting vial and the vial is then carefully filled with plaster of Paris. Vents may be added from the wax model to the surface of the plaster of Paris to allow gases to escape. The canister then goes into a casting furnace to literally burn out the wax model. This leaves an exact 3-D impression of the wax in the now solid plaster. A carefully weighed amount of molten metal of choice is poured down the vent hole into the cavity left by the melted wax model. After the metal solidifies and cools the plaster is broken away from the rough casting inside revealing a reproduction faithful in every detail to the original wax carving.
At this point the casting is a one of a kind creation. It may be the desired final product or the casting may be the master for ongoing mass reproduction. As the latter, the master is cleaned, polished and weighed.
Every detail is crucial as it will be present in every copy made. The master is then moulded in a special rubber compound. The rubber mould of our master can then be injected with molten wax creating an unlimited series of reproductions each to be cast in its turn using the lost wax process. The cost of creating the original model becomes almost negligible as it is spread out over 10â€™s, 100â€™s or even 1,000â€™s of copies. Not so with the one-of-a-kind model where all the costs are concentrated in the one piece.
When intended for mass production, the finished weight of the master is of primary concern. The final casting may be in sterling silver, 10 karat gold or 22 karat. Whatever the choice, the weight of the casting metal will be the greatest part of the cost of the reproduction.
Using the lost wax process for custom design provides the advantage of being able to actually see and try on the piece before proceeding to the casting phase. We can place the stones into the wax model to ensure they will be featured the way we see them in our imagination. This is the time to ensure that you and your designer are on the same â€˜wave lengthâ€™ and you both see the design the same way. The wax may be modified or may have to be completely replaced before proceeding to the much more expensive and final step of casting in precious metals.