Water glass, also known as sodium silicate or liquid glass, is a versatile chemical compound. It is a solution with a wide range of uses across numerous industries.
Understanding Water Glass
Water glass is an aqueous solution of sodium silicate, though potassium silicate is also a form. It typically appears as a viscous, often clear liquid, and feels slippery to the touch. It forms an alkaline solution when dissolved in water.
The name “liquid glass” comes from the fact that it is essentially glass (silicon dioxide) dissolved in water. When the water evaporates, the solution solidifies into a hard, glassy material. Industrially, water glass is produced by heating soda ash (sodium carbonate) and silica sand at high temperatures, typically between 1,000°C and 1,400°C. It is available in both liquid form and as solid lumps or powders.
Common Applications
Water glass is widely used as an adhesive. It forms a strong, glassy gel when it dries, effectively bonding materials like metals, concrete, glass, and porcelain. It can be applied as a thin layer to create a rigid and resilient bond.
In construction, water glass functions as an effective concrete and plaster sealer. It penetrates porous surfaces, reducing porosity and increasing water resistance, which also enhances the material’s strength and density. It is also employed in fireproofing applications, forming a protective barrier on materials like wood and fabric. When exposed to heat, it insulates and blocks oxygen, slowing down combustion.
Historically, water glass was used for preserving eggs. Immersing fresh, unwashed eggs in a solution seals the eggshells, preventing bacteria and moisture loss, allowing eggs to remain fresh for several months without refrigeration. Its alkaline nature also makes it a component in detergents, aiding in breaking down fats, oils, and proteins. In wastewater treatment, water glass acts as a flocculant, helping to aggregate and remove suspended particles and metallic ions from water.
Safe Handling and Storage
Handle water glass with precautions due to its alkaline nature, which can cause irritation to the eyes and skin. Wear personal protective equipment, such as chemical splash goggles and resistant gloves, to prevent direct contact. In case of skin contact, the affected area should be washed thoroughly with plenty of water, and eyes should be rinsed for at least 15 minutes if contact occurs.
Proper ventilation is advised to avoid inhaling mist or spray during handling. Spills of liquid water glass can be very slippery, posing a fall hazard, and when dry, it forms a glassy film that can cause cuts. Contain spilled material with absorbents and transfer to a chemical waste area.
For storage, water glass should be kept in sealed containers in a cool, dry place, ideally at temperatures below 60°C (140°F). Store it away from acids, as it can react with them, and protect it from freezing. Keeping containers closed helps maintain stability and prevents premature drying and solidification.