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.
