Glass strength is affected by sub-critical evolution of surface micro-defects. Crack propagation velocity depends not only on stress but also on chemical-physical interaction between glass atomic structure around the crack tip and environment. In the literature, this phenomenon is known as stress-corrosion and it is related to environmental variables, as temperature and relative humidity. Stress-corrosion theories provide a coherent framing to two phenomena directly measurable, representing respectively a strength decrease over time and a dependence of material strength on applied stress-rate. Many of the published works about stress-corrosion refer to empirical power law functions. This work, starting from an exponential function consistent with the chemical kinetics, aims at providing lifetime curves in function of environmental variables. Within this scope, a simple methodology based on four point bending tests on small specimens is presented.
