A quick primer on bronze casting and foundry editions…
Traditionally sculpture has been produced either as a single piece or in small editions (multiples cast from one mold). A single piece is usually referred to as “unique”–there may be no mold, or the piece may have fabricated parts which are not possible to reproduce in an edition.
Bronze casting, one of the oldest methods of reproduction, has remained essentially unchanged since the Renaissance. A mold made out of rubber, plaster, or other material is used to produce a wax positive (see the apple in the photo), which then has wax rods attached to it which will act as channels for the molten bronze. The wax is then covered with a refractory slurry which hardens into a kind of shell, or else fine sand. This is kiln-dried to burn out the wax. Molten bronze is then poured into the wax cavity. Imperfections in the casting are hand-finished (this is called chasing). Finally the patina, a multi-layered chemical process which affects the color of the finished bronze, is applied, and the piece is waxed. Bronzes that will be displayed outdoors are given an acrylic coating before being waxed.
Sculptors normally make relatively small editions of their work (say, 6 or 12 or 24) because this is all they feel they can sell. Larger commercial foundries may cast work in editions of dozens, or hundreds, and the price per sculpture should decrease accordingly. Sculpture edition numbers are noted the same as print edition numbers, with 1/12 being the first of a planned edition of twelve, 2/12 being the second, etc.
A sculptor is entitled to make one or more “artist’s proofs” of a bronze piece that is not part of the numbered edition. I like to keep proofs in my studio to show prospective clients, or just because I like having them around. At some point, when all of an edition is sold, I literally break the mold so no more can be made.