In the past, electroformed bronze bookends have been called bronze clad or weighted bronze, but electroformed bronze is a much better term because it specifically identifies these bookends by the technique which produced them.
Electroformed bookends are made in several steps:
First, a sculptor produces a full-sized model of a bookend which is then replicated in plaster or similar material, The plaster form is then coated with carbon or other suitable material so that it can function as a cathode in an electrolytic bath. The coated form is then suspended in a bath containing tin and copper ions and an electric current is passed through the bath. Copper mixed with tin (bronze) is deposited on the model in a uniform coating. At this point the model has become bronze plated, this is the same procedure for silver plating, chrome plating, or any other metal-plating operation. .
Metal-plating conventionally produces a very thin coating on an object. For example, most Jennings Brothers bookends are made of gray metal and given a thin electroplated bronze surface. The gray metal provides the structural strength for the bookend; the bronze gives the surface.
The bookends that should be called electroformed are not given a thin coating which is simply a surface. These bookends are given a thick layer of bronze and this layer provides structural strength for the bookends. Thus, the bookends are proper bronze and not simply bronze plated. Each electroformed bookend usually shows a scar on the bolttom where a hook was placed in order to suspend the plaster form bookend in a bath.