Most metal jewellery made today passes through lost-wax casting at some point — the process that converts a wax or resin model into an identical metal piece. It is old (the oldest known cast objects are thousands of years old) and still the backbone of both mass production and one-off commissions.
The process, step by step
A model is made — carved in wax by hand, built in CAD and printed in resin, or cut from casting-sheet wax. The model is attached to a wax stem (the sprue) forming a tree, which is placed in a metal flask and surrounded by investment, a plaster-like material. Once set, the flask goes into a kiln: the burnout heats it in stages until the wax melts out and burns away completely — hence “lost” wax — leaving a negative cavity in the hardened investment. Molten metal is then forced into the cavity, by centrifuge, vacuum or gravity pour. After cooling, the investment is broken away, the cast tree is cut up, and each piece is cleaned, finished and set.
What designers must design for
Casting rewards designs shaped for it: consistent wall thickness, generous fillets where forms meet, sprue points placed where finishing marks will not show, and tolerance for the slight shrinkage of metal cooling in the mould. Thin sections that a fabricator could solder become cast failures; a designer who knows the process specifies what it can deliver.
Learning it hands-on
Casting is taught with real flasks and real pours in the precious-metal-arts programme at JDMIS — see MS400 Casting Metals & Advanced Stone Setting, built on the bench foundation of Metalsmithing 1. The digital route in, from CAD model to cast piece, is covered in the CAD track.