If we examine the records of the art of working metal we find many references to the effect that the lost wax process was in common use almost countless ages ago. One of the earliest records of the casting of bronze by the disappearing wax process is dated 2230 B.C. There is no record of the composition of the investment material used in making these early castings, but it was probably a refractory clay that developed enough green strength after it was poured around the pattern to hold its shape until the hardness was increased by drying. The investment materials that have been in use in the manufacture of jewelry since its discovery all contain two main constituents - a binder or bonding agent and a refractory filler.

Author: Carl H. Schwartz