The art of lost wax casting, a technique that yields intricately
detailed metal, dates back thousands of years with its true origin lost
in ancient history. Lost wax casting is used to mold various types of
metal into intricate pieces of jewelry and artistic sculptures, though
it is also commonly used for industrial components and dental
procedures.
The process of lost wax casting starts with a sculptor crafting a
representation of the desired piece out of wax, creating a pattern with
the same intricate detail that will appear on the metal piece of
jewelry in its final form. Wax "sprues" are included in the creation of
the pattern, which are wax rods or wires that delineate the strategic
placement of channels that will remain open when the final mold is
made. Sprues are not a design element of the final piece, but rather
allow for spaces to remain open in the mold through which the molten
metal that will constitute the final piece will be injected. The
channels imprinted by these sprues will also allow for the wax to exit
the mold.
Once the wax model and its attached sprues are in the desired form, the
wax pattern is covered with a pliable ceramic substance through
pouring, dipping, or both. Care must be taken during this process to
ensure that air bubbles are not present, as any imperfections in the
mold will be visible on the final piece. Once the mold surrounding the
wax pattern reaches the desired thickness, it is allowed time to harden
and then heated in a kiln. As temperatures rise, the wax within is
melted and eradicated through the channels left by the sprues, hence
the name "lost wax." The result of this stage is a strong mold with a
hollow opening in the shape of the original wax design.
Molten metal can then be inserted into the final mold through the
channels, and is usually injected rather than poured in jewelry
crafting so that the metal fills each intricately placed impression in
the mold. When the metal hardens, the mold is removed to reveal the
piece. In the final stages, protrusions such as those created by the
opened channels or other vents must be removed and the metal polished
to its final, lustrous state.
Variations in the lost wax casting process exist, such as the use of
rubber molds rather than ceramic, but the fundamental lost wax
principles remain widely used due to the intricate details that can be
produced in the end. Though modifications have been made to the lost
wax casting process throughout history, the effectiveness of its
underlying process has withstood the test of time.
