Silica

Silica (CAS 7631-86-9), also known as silicon dioxide or SiO2, is a high-purity amorphous mineral used in industrial and consumer product manufacturing.

Where is Silica used?

• Food-contact and additive applications (E551): anticaking agent
• Powder and liquid systems: flow aid and rheology modifier
• Personal care: texture and oil absorption control in pressed powders, dry shampoos and skincare
• Rubber and tire compounding: precipitated silica as reinforcing filler improving rolling resistance and wet grip
• Plastics and polymer processing: fumed silica for viscosity modification
• Adhesives, sealants and coatings: prevents sagging and improves shelf stability
• Printing and packaging: matting agent and anti-slip additive in inks and surface coatings
• Fumed silica, precipitated silica and colloidal silica dispersions suit different processing requirements.
• Crystalline silica in the form of quartz is used as a raw material in industrial processes such as concrete and ceramics.
• Ultra-high-purity silica is used in fused quartz crucibles for semiconductor manufacturing.
• Crystalline silica in tripoli form is used as a filler for polymeric materials, plastics or paints.

Good to know: Pharmaceutical grades meet USP and Ph. Eur. standards; technical grades serve industrial applications. Particle size, surface area and surface treatment vary by grade and determine suitability; hydrophilic or hydrophobic treatments are available.

Formulation notes

• Substitution of materials containing crystalline silica can be done with silicates (almandine) or recycled glass for sandblasting.

Typical specification

• Crystalline silica in tripoli form has particles typically between 1 and 10 µm in size, with particles of 0.1 to 0.2 µm diameter frequently present.
• The main crystalline varieties of silica are quartz, cristobalite and tridymite.

Regulatory status

• Crystalline silica is classified as Group 1 (carcinogenic to humans) by IARC since 1997, updated in 2012.
• EU Directive 2017/2398 set an occupational exposure limit of 0.1 mg/m3 for respirable crystalline silica dust.
• Amorphous silica is classified as Group 3 by IARC.
• In France, the occupational exposure limit for quartz is 0.1 mg/m3.

Frequently asked questions about Silica

What is the occupational exposure limit for cristobalite and tridymite in France?

In France, the occupational exposure limit for cristobalite and tridymite is 0.05 mg/m3.

How does the EU classify work involving exposure to respirable crystalline silica dust?

Work involving exposure to respirable crystalline silica dust from work processes is classified as a carcinogenic process in the EU.

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