The life of high power short pulse flashlamps for dye lasers has been examined and a key degradation process identified. Three main effects have been identified and characterized. These are an initial steep drop in optical output followed by a slow decline in output with continuous running and an output recovery after a rest period. Mass spectroscopy has shown that there is a substantial build-up of oxygen in the flashlamp during the first few pulses. The oxygen is believed to be a result of the break-up of the quartz wall. Using this simple process of wall erosion the three effects above have been explained. This has led to a new model to predict the life of short pulse, high power flashlamps where operational lifetime is dominated by wall erosion rather than thermal stress.