Read Consulting Materials Failure Laboratory was asked to examine a failed coffee mug. This mug was advertised as a “solid soda-lime clear glass mug”. Unfortunately, soda-lime glass is a poor choice for mugs that are filled with hot liquids such as coffee and tea. Its high coefficient of thermal expansion makes it vulnerable to failure. This is especially true when stirring the contents with a hard spoon can damage the glass on the interior wall. The resulting damage can act as a fracture initiation site leading to eventual failure from thermal shock. See Figures Below
In this case, the failure analysis determined that there was “scuffing damage” that lead to eventual failure. Because there were numerous complaints this product was recalled and taken off the market.
