Time‐dependent crack bridging forces were measured at temperatures from 1150° to 1275°C in a vitreous bonded alumina using the rear‐notched, short double cantilever beam technique. Glassy ligaments were observed to bridge the crack even after the crack entered the rear notch. The crack bridging force exhibited both a temperature and displacement rate dependency. A model was developed that describes this temperature and time dependence of the bridging forces that result from the viscous glass br