Silicon dioxide

Silicon dioxide (CAS 112945-52-5), commercially known as synthetic amorphous silica or fumed silica, is a high-purity engineered form of silica produced through vapor-phase hydrolysis.

Where is Silicon dioxide used?

• Coatings and adhesives: thixotropic agent preventing sagging in films and controlling flow in sealants and structural adhesives
• Personal care: texture adjustment, powder flowability and emulsion stabilization in sunscreens and pressed cosmetics; in cosmetic products such as make-up, shampoos and skin care products it is present for its texture-improving and oil-absorbing properties.
• Lubricants: thickener in grease formulations and reinforcing filler for thermal stability under load
• Plastics and polymer processing: anti-blocking agent in film extrusion and pigment dispersion stabilization in masterbatches
• It is manufactured to deliver controlled rheology modification, anti-settling and foam suppression.
• In sunscreen formulations it diffuses solar radiation.
• As an anticaking agent and viscosity adjuster in inks, paints and polyester resins.
• As a drying agent in varnishes, helping prevent oxidation and corrosion.

Good to know: Unlike crystalline or precipitated grades, this material is manufactured specifically for controlled rheology modification, anti-settling and foam suppression. Standard grades include food-grade (FCC compliant) and technical grades, with surface area specifications typically used to differentiate reinforcing versus flow-aid applications.

Formulation notes

• Incompatible with hydrogen fluoride.

Typical specification

• pH 5 to 8 at 400 g/L at 20 °C.
• E 551 is synthetic amorphous silica with no crystalline structure that has not been coated or surface-modified.
• SAS consists of nearly spherical nanoparticles, mostly between 2 nm and 28 nm, which assemble into complex aggregates.

Regulatory status

• Not classified as a hazardous substance or mixture.

Storage, packaging and handling

• Store in a cool place and keep the container tightly closed in a dry, well-ventilated place.
• Must be packaged protected from moisture, light and weather conditions.

Technical content is compiled and updated by the SoleChem product team from public technical sources; the certificate of analysis (COA) governs product-specific specifications.