Sodium Hydroxide 50% Solution

Fifty percent sodium hydroxide is the highest concentration that stays liquid at normal ambient temperatures, which makes it the standard shipping and handling form for caustic soda.

Typical uses

• pH adjustment and acid neutralisation in wastewater treatment
• Alkaline cleaning and degreasing, either neat or as a builder in a formulated cleaner
• Aluminium etching and metal surface preparation
• Pulp, textile, and process chemistry
• CIP systems in food and beverage plants, where grade matters — ask for the appropriate grade

Handling

Fifty percent solution crystallises below roughly 12 °C (54 °F). In cooler months, insulated or heat-traced storage prevents a tank that will not pump. If you are ordering into an unheated outdoor tank in winter, consider the 25% solution instead.

Dilution is strongly exothermic. Always add caustic to water, never the reverse, and control the addition rate.

Storage compatibility

Carbon steel, 304 and 316 stainless, and HDPE are all suitable at this concentration and temperature. Aluminium, zinc, tin, and galvanised surfaces are attacked and must be avoided. Keep separated from acids — the reaction is violent.