The artwork is now going to need a gating system applied to the outside and the inside of the artwork and plugs will be cut out of the wax.  The spruing fixtures range in size from a cross cup, a round cup or bars for the bigger pieces. At this point the pre-core process is appropriate for smaller pieces. The sprues or gates serve several purposes.  The gates act as an avenue for the bronze to flow in and a way for the air to escape. When a material is heated until its melting point it has expanded as much as possible.  Once it begins the cooling process the bronze will start shrinking. We must accommodate for this in the spruing.  By identifying the thick spots and the thin spots, we can get as close to a perfect casting as science will allow. Madd Castings also has a point source smoke evacuation to help keep the air clean.  This essentially is a large fan with a vacuum connected that sucks the air into a filter to clean the air inside the foundry.