The first is called the direct additive method whereby wax is added to the form, and Yes, you guessed it, the second is the direct subtractive method where some specialized tools as old dental picks, spatulas, soldering irons, pliers, any old piece of metal or razor blades are utilized when heated to remove wax from the form. During the construction process, one usually employs both methods toward a finished product. The next stage in the lost wax process is configuring your artwork to accept hot bronze. A larger sprue is then inserted into the bottom of the cup, and melted to bond with the styrofoam. The other end is attached to the more massive part of the sculpture.
Smaller tubing is employed to channel all the wax out of the casting when the form is heated.
This is called the investment casting process. No, not money or acting for a part in a play, nor the time in making your sculpture. The artwork is submerged into a tank of wet plaster, or a refractory slurry, and then coated with sand. This is allowed to dry. When all the molds have dried, the molds are heated to a high temperature so the wax inside finds its way to the outside.