Sodium metasilicate

Sodium metasilicate (CAS 6834-92-0), also sold under the E-number E550, is an inorganic alkali salt used across industrial cleaning, water treatment, and surface processing operations. It functions primarily as a builder, pH regulator, and corrosion inhibitor in formulated products and process chemicals. In industrial and institutional cleaning, it acts as a detergent builder.

This chemical boosts alkalinity, sequesters hardness ions, and improves soil removal in heavy-duty formulations. Textile and leather processors use it to prepare fiber surfaces and control bath pH. It is also utilized during scouring and dyeing to improve dye uptake consistency. Water treatment operations apply it as a corrosion inhibitor for metal pipelines to protect iron and steel surfaces.

The compound forms a protective silicate film on these surfaces to prevent degradation. Pulp and paper producers incorporate it into bleaching and sizing processes to stabilize peroxide bleach. It is also used to control effluent pH in paper manufacturing. Sodium metasilicate is supplied as an anhydrous powder or pentahydrate granules, with the pentahydrate form being the most common.

Technical grade is the standard offering for industrial use, with food-grade material available under the E550 designation for indirect contact or food-processing applications. Bulk supply is typically available in bags or bulk sacks. The product is specified by its silica-to-sodium oxide ratio and total alkalinity content for various industrial requirements.