Glass Failure Analysis Of Bottle Defect

California Glass Expert Witness was assigned to determine the cause of failure of wine bottles at the manufacturing facility. During processing the bottles had a higher than normal failure rate. A root cause failure analysis was performed by the glass failure analysis expert witness. He inspected a large number of whole bottles and removed those with visible defects. In addition failure analysis was performed on those bottles that failed in manufacturing. Above left is a photomicrograph of a "crush" or "bruise" found on one of the unbroken bottles. This type of defect was found on several bottles. This bottle defect appears to be a result of impact damage. Curiously, there is an open surface bubble (i.e. seed) in the vacinity of the bruise. Upper right is a photomicrograph of the fracture surface of one of the failed bottles. The origin of this failure is at the same location on the bottle as the bruises found on whole bottles. In addition, this failure started at a small diameter bruise. The repetitive nature of the location and the nature of the defect indicates that this manufacturing defect is caused by the glass handling machinery either at the bottle manufacturing facility or at the bottling plant. Also, this damage is severe enough to cause bottle failure.

Glass Failure Analysis of Tramp Glass

As a part of a product liability case, a glass failure expert was asked to determine if a piece of "tramp glass" found by a consumer (Upper left photo) was put into the bottle after it was opened. There was a companion bottle from the same six pack that also had glass contamination(upper right photo). If the tramp glass in the subject bottle was planted, then the glass in the "sister bottle" was also put in by the consumer. These were "twist off" bottles; therefore, it was decided that if the torque needed to remove the cap on the sister bottle was low, this would indicate the cap had been previously removed by the consumer. The removal torque was measured on the sister bottle, and it was twice that measured on control bottles. Thus, the cap on the sister bottle had not been removed, and the glass contamination entered this bottle during bottle manufacturing or bottle filling. From this it was concluded that the tramp glass in the subject bottle is also a manufacturing defect.