Sodium fluorosilicate

Sodium fluorosilicate (CAS 16893-85-9), also known as sodium hexafluorosilicate or sodium fluosilicate, is an inorganic fluoride salt used industrially as a biocide, curing agent, and surface-hardening additive. It delivers fluoride activity in controlled-release form, making it suitable for applications where direct fluoride addition would be too aggressive or difficult to manage for the operator.

In building and construction, it functions as a concrete densifier and hardener, reacting with surface calcium compounds to improve wear resistance in industrial flooring and cement-based coatings. Water treatment operations use it as a fluoridation source, dosing municipal supplies where silicofluoride compounds are the preferred fluoride carrier for public health initiatives.

Textile and leather processing incorporates it as a preservative and mothproofing agent, protecting finished goods during storage and transit from biological degradation and pests. In agriculture, it serves as an active ingredient in pesticide formulations targeting wood-boring insects and soil pests, providing effective protection for crops and timber products.

Sodium fluorosilicate is supplied as a white crystalline powder or fine granules. Standard commercial grades include technical grade for industrial and agricultural use, with purity levels typically specified at 98–99%. Water treatment applications may require grades meeting specific national or regional drinking water standards to ensure safety and compliance with local environmental regulations.