By means of special machines, wax is injected into the die and in this way we get as many wax patterns as finished castings we plan to manufacture.
There are some pieces with complicated internal cavities or with sharp internal corners, which are impossible to make in a single die. For them it is necessary to use special cores, made of ceramic or water soluble wax, which will be located in the die prior to the injection of the wax patterns. These cores have got special shapes and outlines and must be studied for every specific case.

The water soluble cores will melt by putting the wax assembly into water, whereas the ceramic cores will remain inside the patterns, and will be removed from them in successive operations.