The remarkable optical properties of switchable mirrors, i.e. the ability of lanthanide-magnesium films to switch reversibly between reflecting and transparent states by changing the hydrogen concentration, are interesting for several applications. Since for any application a high cycling durability is necessary, we have studied the durability of various, differently prepared, switchable mirrors. As a model system we have chosen to switch in a 1 M KOH solution. Typical degeneration Features that were found included slower kinetics, oxidation and delamination upon cycling of the switchable mirror. Of the various attempts to improve the cycle lifetime: we obtained the best results by using a switchable mirror loaded with hydrogen during deposition.