The solid form of sodium hydroxide is caustic soda flakes. There are no foreign matter, dirt or other visible impurities in it. Caustic Soda Flakes are formed when the solution of Sodium hydroxide (NaOH) in water is evaporated. Caustic soda flakes are primarily used in textile and paper processing, soap making, and detergent manufacturing. Using it as an intermediate for dyes, pigments, or agrochemicals is also common. In addition, it is also used in several inorganic chemicals like phosphates, sulphites, etc.