Glass bottles and jars: thermal stress and annealing
Glass in the molding process and mold contact, as well as by the cooling wind, the rapid cooling of the glass (such as in 10 seconds from 1100 ℃ down to 600 ℃), the glass inside and outside will produce a large temperature difference, due to the temperature difference of the stress produced is called thermal stress. (The force remaining inside the glass puts the structure of the molecules in a state of deformation)