Pour, Pouring. The principle act of casting by placing liquid substance in a prepared mold. In metalcasting not only is the temperature of the metal of vital importance, but other factors as well, including preparation of the mold with sprues, air channels (vents), release agent, the speed of pouring, the composition of metal alloy, and others. Pouring cannot be hurried or prolonged too long, as the metal must flow into every cavity allowing all air to escape through vents. The metal should not be disturbed or agitated when pouring. Thus many variables must be controlled by the metalcaster.