Over the years, Read Consulting glass failure analysis laboratory has performed numerous glass failure analyses on broken borosilicate glass coffee presses. The presses are made from 2 to 3mm thick annealed low expansion borosilicate glass. The low expansion glass is required to reduce thermal shock when hot liquid is poured into the cold glass container. The subject carafe failed at the bottom. The glass failure analysis showed that the cracking initiated at inner wall damage. Possibly the coffee had been stirred with a hard spoon which damaged the inner wall. This damage acted as a stress riser causing the failure. It is advised that one not use hard spoon or knife to stir the coffee in the press. Contact with the glass can damage the surface and cause eventual failure.