Hexafluorosilicic acid

Hexafluorosilicic acid (CAS 16961-83-4), also known as fluorosilicic acid, is a strong inorganic acid supplied primarily as an aqueous solution.

Where is Hexafluorosilicic acid used?

• Municipal water treatment: most commonly used chemical for drinking water fluoridation, dosed to regulated concentration targets
• Construction and concrete: hardens and densifies cementitious surfaces by reacting with calcium compounds, forming insoluble silicates that reduce porosity and improve wear resistance
• Metal surface treatment: etchant and adhesion promoter for preparing substrates prior to coating or plating
• Mining: ore processing and pH-regulating agent in leaching circuits for mineral extraction
• It is produced as a byproduct of phosphate fertilizer manufacturing.

Good to know: Product quality is typically referenced against water treatment authority standards or regional regulatory requirements.

Commercial specifications

• Aqueous solution at 20–25% and 23% w/w concentrations
• Higher-concentration solutions up to approximately 35% for industrial uses