As well as replicating complicated surfaces and shapes with electroforming, BJS Gold also works closely with a major art foundry in the UK for its European clients and another in Los Angeles for its US clients.
The process of investment casting or lost-wax casting starts with a design which is turned in to a wax shape either through CAD drawing and 3D printing, or by the shape being hand carve.
Wax rods or spues are added to create the paths down which the metal flows and the wax is dipped (invested), firstly in a slurry of silica and then into a sand-like stucco, or dry crystalline silica. This is baked in an oven to harden, creating a ceramic shell mould. Whilst this happens, the wax melts and pours out, leaving a hollow shape for molten metal to be poured into.
Pieces can then be welded or soldered together, filed, papered and polished as required, with details re-chased in by hand.
Allowance should be made for a shrinkage of up to 10% in size.
Gold, silver, bronze and brass sculptures and objets d’art are generally cast in this way.