Aqua complexes and metal hydroxides can be dehydrated by thermal treatment at a range of temperatures from 50℃ to 600℃. Low hydrolysable CuBr2·4H2O becomes anhydrous below 100℃ while NaOH is converted to Na2O above 500℃. The presence of water can be expected in wet ULES materials if the dehydration temperature exceeds the sintering temperature.