Goldweights:

The Lost Wax Casting Method.

1. Wax Model: Lost-wax casting is done from a full- size beeswax model made by the goldsmith, who then adds a casting channel, or sprue, in wax to the finished model.

2. Wax Model with wax sprue: Model and sprue are then covered with a thin coating made of two parts finely ground charcoal to one part finely ground clay. This thick liquid material, or slip, is applied very carefully with a feather so that every detail and crevice of the model will be recorded in the finished casting.

3. Wax Model and sprue in two layers of charcoal clay mixture inner mold: When the first coat is dry, a thicker second coat of one part charcoal to two parts clay is applied, and after this dries, a final coat of pure clay covers everything.
4. Complete Mold with outer clay coat after wax burnout, above clay crucible with brass: When dried, mold material is scraped off the end of the wax sprue, and the mold is placed over a fire with the exposed sprue end down, so that the entire wax model with sprue melts and runs out, leaving a cavity in the shape of the model.

5. Empty mold seated in full crucible: The empty mold is now positioned upside down over a clay crucible holding brass for casting and a thick clay shell is built over both elements, joining and completely hiding them.
(Below) 6. Mold and crucible in outer clay coating, and 7. Mold cross-section The resulting dumbbell-shaped mold is placed in a forced-air furnace with the crucible on the bottom, in which the brass melts.

8. Inverted mold filled with molten brass By timing this process and watching the glowing color of the hot mold, the goldsmith knows when to grasp it by its constricted center with iron tongs and invert it, so that molten brass runs down the sprue and fills the model cavity.

9. Casting and sprue after removal from mold: Once cooled, the mold is destroyed to reach the casting of the model and its sprue.

10. Finished casting: After the sprue is clipped off and the casting cleaned and polished, the process is complete.

A goldsmith's skill is vital, because the entire casting process is hidden; errors cannot be detected until the mold is destroyed, and only a few repairs are possible. Properly cast parts might be clipped off by the smith or owner in the case of a goldweight too heavy for its designated weight. This is common on geometric weights, as well as for figurative ones. Geometric weights out of standard because of wear, casting error, or a change in the weight system could be augmented with lead from bullets, which was worked into the pattern. Wire or chain could be added to figurative weights. These were useful objects; function was more important than aesthetic appeal.
Proceed through this exhibit, return to the Doorway , or compare with the Yoruba section.

Last updated 29 March 1995.