Glass Expert Analyzes Wine Bottle Defect

A glass expert was asked to examine poor quality bottles received by a winery. The issue was whether this product defect would significantly lower the strength of the bottle and would present a product liability problem. The photo on the upper left is a photograph of the manufacturing defect. It is a 4 inch horizontal "gash". The center picture is a photo-micrograph of the defect cross-section. The cross-section shows that the edges of the defect are rounded. This is a molding defect that occured when the glass was at or above the its softening point. The edges of the defect are rounded; therefore, in the opinion of a manufacturing engineer, they are unlikely to cause a low stress bottle failure. The picture on the upper right is a photo-micrograph of the top of the defect. There is a thin sheet of glass over the center mound of the defect. It is believed that this defect was formed in the blow molding step of the bottle manufacturing process.

Failure Analysis Expert Performs Glass Failure Analysis

Glass expert performs a failure analysis on a failed tempered glass door. The spontaneous glass failure was analyzed to determine the cause of failure. This was one of several doors that failed spontaneously on a new high rise. Fortunately the door did not fall apart; thus, the failure origin could be preserved. The upper left photo shows the failure origin (arrow). The origin was taken apart, and at the center was a spherical 180 micron diameter nickel sulfide particle, NiS particle. During the glass failure analysis, a scanning electron microscope, SEM, image of the particle is shown in the upper right. Elemental analysis of the particle showed it to consist of nickel and sulfur. The SEM image also shows initial Wallner lines that are spiral in shape and are leaving the particle. This identifies the NiS particle as the cause of the failure