Drums for dry milling to soften the leather by mechanical shaking to controlled moisture and temperature. In addition to the simple action of softening, some cleaning chemicals recipes may be used to obtain desired special fashion effects; for which the drums may be equipped by chemical dosing devices. Drums for dry milling to soften the leather by mechanical shaking to controlled moisture and temperature. In addition to the simple action of softening, some cleaning chemicals recipes may be used to obtain desired special fashion effects; for which the drums may be equipped by chemical dosing devices.