Lost-wax casting, sometimes called cire perdue, is the process by which a wax model of an object is encased in a refractory investment, the wax burned away in a kiln, and molten metal poured or vacuum-drawn into the resulting void. Once the metal has solidified the investment is broken away to reveal the casting. The technique has been the backbone of jewellery production for some five thousand years, with archaeological examples from the Indus Valley and the Aegean.

Modern workflow

The contemporary jeweller carves or injects a wax pattern, attaches it to a sprue tree, invests the tree in a steel flask filled with gypsum-bonded investment, and runs a multi-stage burnout cycle that can exceed eight hours. The flask is then transferred to a centrifugal or vacuum casting machine and metal at a controlled superheat is delivered into the cavity. After quenching, the cast tree is cut down, sprues removed, and individual pieces enter finishing.

Why it persists

Lost-wax casting reproduces fine surface detail, undercuts, and complex three-dimensional geometries that cannot be raised, milled, or stamped. It also accepts wax patterns from any source, whether hand-carved, injected from a rubber mould, or printed in castable resin, which is why it has absorbed every wave of new technology rather than being displaced by it.