Sodium Silicate

Overview

Sodium Silicate (CAS No: 1344-09-8), commonly known as "water glass," is an alkaline inorganic compound. It is a family of compounds formed by the combination of sodium oxide (Na₂O) and silicon dioxide (SiO₂) in various ratios.

It is typically found as a clear, colorless, viscous liquid or white solid powder. It mixes easily with water and exhibits strong alkaline properties. In industrial applications, it is usually used in solution form and exhibits different properties depending on the SiO₂:Na₂O ratio.

Applications

Sodium Silicate has a wide range of industrial and commercial applications:

Technical Specifications

Safety Information

Hazard Symbols and Statements

Corrosive Irritant Environmental Hazard

Personal Protective Equipment (PPE)

• Chemical resistant gloves (nitrile or neoprene)
• Protective goggles or face shield
• Respiratory protection against acid vapors (at high concentrations)
• Chemical resistant apron or coveralls

Storage Conditions

• Store in a cool, dry, well-ventilated area
• Keep in original container tightly closed
• Storage temperature: 5-40°C
• Keep away from acids and neutralizing substances
• Protect from freezing (especially in solution form)

Fire Fighting

• Suitable extinguishers: Water spray, dry chemical, CO₂
• Toxic gases (sodium oxide) may be released during fire
• Firefighting personnel should use appropriate respiratory protection
• Large amounts of heat may be released when using water

Handling and Storage

Transportation

• Ensure containers are tightly closed
• Transport separately from acids and neutralizing substances
• Protect from temperature fluctuations during transport
• Have neutralizing materials (sand, clay) available for spills
• Ensure adequate ventilation in transport vehicles

Storage

• Store in polyethylene, stainless steel or rubber-lined tanks
• Avoid aluminum, zinc or tin-coated containers
• Display appropriate signs in storage areas
• Provide secondary containment when storing large quantities
• Use heating systems to prevent freezing risk

Spill Response Measures

• Evacuate exposed personnel from the area
• Use appropriate personal protective equipment
• Use acid neutralizing materials (sand, sodium bicarbonate)
• Clean by diluting with plenty of water
• Neutralize wastewater before disposal

Regulatory Information

GHS Classification

• Skin Corrosion/Irritation Category 1B
• Serious Eye Damage/Eye Irritation Category 1
• Acute Toxicity (Oral) Category 4

Important Regulations

• REACH: Registered
• EPA: Listed on TSCA Inventory
• EINECS: 215-687-4
• WHO: Approved for use in food packaging

Industrial Standards

• ISO 1689: Industrial specifications for sodium silicates
• ASTM D501: Sodium silicate analysis methods
• EN 1594: Standards for construction applications
• FDA 21 CFR 182.90: Use in food contact applications

Environmental Information

Environmental Impact

Sodium silicate can cause high pH in aquatic environments. At high concentrations, it may be harmful to aquatic life. It neutralizes in soil and is biodegradable.

Biodegradation

• Air: Does not degrade by photochemical reactions
• Water: Quickly neutralizes in dilute solutions
• Soil: Neutralizes by reacting with soil acids

Waste Management

• Not classified as hazardous waste
• Can be disposed of by neutralization with acids
• Should not be discharged into sewers or surface waters undiluted
• Dispose of in accordance with local regulations

Frequently Asked Questions

Why is sodium silicate called "water glass"?

Sodium silicate gets this name because when melted and cooled, it forms a glass-like transparent solid. Its ability to form a viscous, glass-clear solution when dissolved in water also supports this naming.

Why does sodium silicate solution gel over time?

Sodium silicate solutions can polymerize and form gels in acidic environments or when stored for long periods. This process depends on the SiO₂:Na₂O ratio, concentration, and temperature. Proper storage conditions should be maintained to prevent gelling.

What effect does sodium silicate have on concrete?

Sodium silicate acts as an accelerator in concrete, shortening the setting time. It also reduces concrete porosity, providing waterproofing and increasing strength. It is also used in the production of fire-resistant concrete.

What should I do if sodium silicate solution comes into contact with skin?

Remove contaminated clothing immediately and wash skin thoroughly with plenty of water and soap for at least 15 minutes. If irritation persists, seek medical attention. In case of eye contact, rinse eyes with plenty of water for at least 15 minutes and seek immediate medical attention.

What is the shelf life of sodium silicate?

When stored under proper conditions (in sealed container, cool and dry environment), sodium silicate solutions typically have a shelf life of 12 months. The solid form has a longer shelf life (24 months). Freezing or extreme temperatures may shorten the shelf life.