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Fumed silica, also known as pyrogenic silica, is a non-crystalline, fine-grain, low density and high surface area silica. Not to be confused with silica fume, also known as microsilica.

Contents 1 Properties 2 Production 3 Applications 4 Health issues 5 See also 6 References

[edit] Properties

Fumed silica has a very strong thickening effect. Primary particle size is 5–50 nm. The particles are non-porous and have a surface of 50–600 m²/g. Density 2.2 g/cm³.

[edit] Production

Fumed silica is made from flame pyrolysis of silicon tetrachloride or from quartz sand vaporized in a 3000°C electric arc.^[1] Major global producers are Evonik, Cabot and Wacker Chemie-Dow Corning.

[edit] Applications

Fumed silica serves as a universal thickening agent, a thickener in milkshakes, and a anticaking agent in powdered foods. Like silica gel, it serves as a desiccant. It is used in cosmetics for its light-diffusing properties. It is used as a light abrasive, in products like toothpaste. Other uses include filler in silicone elastomer and viscosity adjustment in paints, coatings, printing inks, adhesives and unsaturated polyester resins.

[edit] Health issues

Fumed silica is not listed as a carcinogen by OSHA, IARC, or NTP. Due to its fineness and thinness, fumed silica can easily become airborne, making it an inhalation risk, capable of causing irritation.

[edit] See also

• Fused quartz
• Hydrophobic silica
• Precipitated silica

[edit] References