Reno Refcast LoCem 7020 was developed for and displays exceptional resistance to all common forms of alkali found in molten aluminum alloys. They are calcium, lithium, and sodium.  This mullite-based, silicon carbide enhanced low cement resists both alkali attack and oxide buildup, while showing excellent resistance to aluminum penetration.  High strength and thermal shock resistance are an added benefit.  Truly the finest product in its class.