Analysis of Failed Glass Baking Dish

Glass failure analysis expert analyzes failed glass baking dish”Pyrex”. Traditionally, glass baking dishes have been made from annealed borasilicate glass (i.e. Pyrex glass). Now baking dishes are made from tempered glass. The glass is still called pyrex but it is really tempered glass (soda lime). As a result of this change, the newer dishes are labeled to be safer because they are made from tempered glass. Given this, a person was injured by a failed baking dish that was sold as tempered glass. A failure analysis was performed on the subject dish.
The failed dish is shown above . This dish failed as a result of a blow to the region indicated by the arrow in the figure. The fracture pattern and the size of the resulting pieces proves that this dish is made from annealed glass; therefore, it is not made as advertised. It is not made from tempered glass.