A wedge-shaped dwell mark is shown in this top-down image at the fractured shoulder of a pharmaceutical vial. In this case, the dwell mark indicates the existence of a check prior to the fracture of the shoulder. Metal smears along the seam show that the check was created by abnormal contact between the container and the blow mold. Although the check did not cause a critical defect (i.e. leaking product or glass in product), it would have lowered the strength of the vial. The check was intentionally broken open in our laboratory to expose it for analysis.