Cores, if any, are formed of ceramic material and imbedded in the pattern wax. The ceramic core prints are exposed from the pattern wax and imbedded directly in the mold during investing. The wax patterns, typically, are made in water cooled dies. The main pattern is formed by injecting wax into the die. Removal of the pattern from the die requires one or more parting lines.
Ejector pins help with the withdrawal of the pattern.
Cores are inserted in the die prior to closing of the die and injection of the wax. For small castings several patterns can be connected in a cluster. The gating system is often formed by attaching standard wax components to the pattern. The expense of making dies is justified for production runs of large numbers of castings. On the other hand, the lost wax process has been used for millennia for the one of a kind art casting.