... caustic soda has very strong hygroscopicity. Apt to dissolve it in water, send out heat when dissolving, the aqueous solution ... is widely used as alkaline desiccant in paper, aluminum smelting, refining tungsten, rayon and soap manufacturing. In addition, in the production of dyes, ... .005% Max.0.001% Max Storage and transport: Stored in a dry,ventilative and clean warehouse; kept away from moisture ...