... or granules, soluble in water,insoluble in alcohol and Sodium metasilicate pentahydrate is strongly alkaline, having strong capacity of ... , preventing corrosion for metal (zinc, aluminum, etc.). Therefore, sodium metasilicate pentahydrate is widely used for the manufacture of a ... , insoluble in alcohol or in acid producing an alkaline solution, very hygroscopic when reacting with CO2 and water from ...