For some castings and applications, it is important for foundries to determine whether specific alloys are more brittle or ductile. Charpy impact testing of castings is a common method of making this determination. Charpy impact testing uses a standard notched sample, which is struck by a specific weight pendulum raised to a predetermined height. The amount of energy that is absorbed when the sample fracture indicates the toughness of the test material. Fractures requiring more energy indicate a ductile alloy. Less energy indicates a more brittle alloy.