The art of lost wax casting, a technique that yields intricately detailed metal, dates back thousands of years with its true origin lost in ancient history. Lost wax casting is used to mold various types of metal into intricate pieces of jewelry and artistic sculptures, although it is also commonly used for industrial components and dental procedures.
The process of lost wax casting starts with a sculptor crafting a representation of the desired piece out of wax, creating a pattern with the same intricate detail that will appear on the metal piece of jewelry in its final form. Wax "sprues" are included in the creation of the pattern, which are wax rods or wires that delineate the strategic placement of channels that will remain open when the final mold is made. Sprues are not a design element of the final piece, but rather allow for spaces to remain open in the mold through which the molten metal that will determine the final piece will be injected. The channels imprinted by these sprues will also allow for the wax to exit the mold.
Once the wax model and its attached sprues are in the desired form, the wax pattern is covered with a biable ceramic substance through pouring, dipping, or both. Care must be taken during this process to ensure that air bubbles are not present, as any imperfections in the mold will be visible on the final piece. Once the mold surrounding the wax pattern reaches the desired thickness, it is allowed time to harden and then heated in a kiln. As temperatures rise, the wax within is melted and eradicated through the channels left by the sprues, hence the name "lost wax." The result of this stage is a strong mold with a hollow opening in the shape of the original wax design.
Molten metal can then be inserted into the final mold through the channels, and is usually injected rather than scattered in jewelry crafting so that the metal fills each intricately placed impression in the mold. When the metal hardens, the mold is removed to reveal the piece. In the final stages, protrusions such as those created by the opened channels or other vents must be removed and the metal polished to its final, lustrous state.
Variations in the lost wax casting process exist, such as the use of rubber molds rather than ceramic, but the fundamental lost wax principles remain widely used due to the intricate details that can be produced in the end. Although definitions have been made to the lost wax casting process through history, the effectiveness of its underlining process has withstood the test of time.