Sodium Silicate (Na₂SiO₃ – Liquid Glass): A Comprehensive Guide: Properties, Applications, and Where to Buy in 2026
Sodium Silicate (Na₂SiO₃, water glass, CAS 1344-09-8) is an alkali silicate compound in the form of a viscous, colorless to pale yellow liquid that is completely soluble in water. Na₂SiO₃ is characterized by its SiO₂/Na₂O ratio (modulus)—a parameter that determines its properties and applications: a low modulus (2.0–2.5) for detergents and wastewater treatment, and a high modulus (3.0–3.5) for adhesives, ceramics, and heat-resistant materials. Loc Thien Chemicals supplies B2B-grade sodium silicate in a variety of modulus ranges, accompanied by COA/MSDS per batch.
This article is a comprehensive guide to sodium silicate for engineers and industrial chemical buyers: properties, modulus ranges, 5 main applications, setting mechanism, storage, and reputable suppliers.
5 Key Points to Remember:
- Na₂SiO₃ (CAS 1344-09-8) — a viscous liquid, alkaline (pH 11–13), highly soluble in water.
- Modulus (SiO₂/Na₂O ratio) is a critical parameter: 2.0–2.5 for cleaning/wastewater treatment; 3.0–3.5 for adhesives/ceramics/heat-resistant applications. Choosing the wrong modulus = application failure.
- 5 core applications: Adhesives (cardboard, paper tubes), ceramics and heat-resistant materials, construction (waterproofing, rapid setting), wastewater treatment (flocculation, sedimentation aids), and paper production.
- Curing mechanism: Na₂SiO₃ + CO₂ (air) → SiO₂ gel + Na₂CO₃ — or curing with acid/cement.
- B2B Purchasing: Get a quote in 15 minutes via hotline 0979 891 929; select modulus based on application; COA/MSDS provided per batch.
What is Sodium Silicate? Physical and Chemical Properties
Sodium Silicate (Na₂SiO₃, also known as water glass) is a sodium silicate salt, commonly found as a clear or slightly pale yellow viscous liquid. The compound is produced by melting quartz sand (SiO₂) with soda (Na₂CO₃) at 1,300–1,500°C, then dissolving the solid product in water under high pressure.
The properties of Na₂SiO₃ are determined by the modulus—the molar ratio of SiO₂ to Na₂O:
| SiO₂/Na₂O Ratio | Modulus | Properties | Main Applications |
|---|---|---|---|
| 2.0–2.5 | Low | Rapidly soluble, high alkalinity, low viscosity | Detergents, wastewater treatment, paper |
| 2.5–3.0 | Medium | Balanced adhesion–alkalinity | Multipurpose adhesives |
| 3.0–3.5 | High | Strong adhesion, rapid curing with CO₂ | Ceramics, refractory materials, construction |
| Criteria | Sodium Silicate (Na₂SiO₃) |
|---|---|
| CAS Number | 1344-09-8 |
| Formula | Na₂O·nSiO₂ (n = 2.0–3.5) |
| Commercial Form | Viscous liquid solution, 35–50°Be |
| pH (solution) | 11–13 (strongly alkaline) |
| Density | 1.35–1.55 g/mL depending on concentration |
| Packaging | 200-liter drums · 1,000-liter IBCs · Tank trucks |
| Documents | COA · MSDS/SDS · VAT invoice |
5 Main Applications of Sodium Silicate
1. Industrial Binder
Na₂SiO₃ with a modulus of 3.0–3.5 is a key binder in the production of paper tubes, corrugated boxes, and honeycomb core panels. Mechanism: Na₂SiO₃ penetrates the paper fibers and reacts with atmospheric CO₂ to form a hard SiO₂ gel—bonding the paper layers together. Advantages: odorless, non-toxic after curing, and offers better heat resistance than organic adhesives.
2. Ceramics & Heat-Resistant Materials
In technical ceramics and refractory materials, Na₂SiO₃ serves as an inorganic binder for heat-resistant powders (Al₂O₃, MgO, ZrO₂) prior to firing. At high temperatures, Na₂SiO₃ melts to form a liquid phase that promotes sintering, increasing the density and mechanical strength of the ceramic product.
3. Construction — Waterproofing & Rapid Setting
Na₂SiO₃ is sprayed onto the surface of fresh concrete or mixed into cement mortar to: (a) provide waterproofing — Na₂SiO₃ reacts with Ca(OH)₂ in the cement to form C-S-H gel that fills voids; (b) rapid setting — shorten the setting time, which is particularly useful for emergency repairs and underwater construction.
4. Wastewater Treatment
Low-modulus Na₂SiO₃ (2.0–2.5) is used in wastewater treatment as a coagulant aid and corrosion inhibitor. Silicate reacts with multivalent metal ions (Fe³⁺, Al³⁺) to form insoluble complexes, supporting the flocculation process—similar to PAC but without residual aluminum or chlorine. At the same time, silicate forms a thin protective film that shields pipes from corrosion.
5. Paper and Pulp Production
Na₂SiO₃ is used in the bleaching of pulp with H₂O₂: silicate stabilizes H₂O₂, prevents its decomposition by metal ions, and buffers the pH within the optimal range of 10.5–11.0. Furthermore, Na₂SiO₃ serves as a water-repellent agent for kraft paper and packaging paper.
Hardening Mechanisms of Sodium Silicate
There are three main hardening mechanisms:
| Mechanism | Process | Application |
|---|---|---|
| CO₂ (air) | Na₂SiO₃ + CO₂ → SiO₂↓ (gel) + Na₂CO₃ | Bonding of cardboard, paper tubes |
| Acid / acid salt | Na₂SiO₃ + H⁺ → SiO₂↓ + Na⁺ | Heat-resistant molds |
| Cement / lime | Na₂SiO₃ + Ca(OH)₂ → C-S-H gel | Waterproofing, concrete repair |
CO₂ curing is the most common method in industry: simply leave the product exposed to air, and natural CO₂ will react to cause gradual curing. The process can be accelerated using compressed CO₂ or mild heating.
Storage and Safety Guidelines
Na₂SiO₃ is an alkaline chemical (pH 11–13)—it is less corrosive than NaOH but still requires PPE: rubber gloves, safety goggles. If it comes into contact with skin: rinse with clean water. If it comes into contact with eyes: rinse for ≥15 minutes and seek medical attention.
Storage: Store in sealed HDPE or carbon steel drums in a dry, cool, well-ventilated area. Avoid temperatures below 0°C (may crystallize) and above 40°C (water evaporation, increased viscosity). Do not store in aluminum drums—reacts to produce H₂ gas. Typical shelf life: 6–12 months under proper storage conditions.
Loc Thien — B2B Supplier of Sodium Silicate
Loc Thien Chemicals supplies Sodium Silicate (liquid glass) with a range of moduli for various industries. Capabilities:
1. Range of moduli: Supplies Na₂SiO₃ with moduli ranging from 2.0 to 3.5 based on application requirements. Consultation on modulus selection based on actual intended use.
2. Nationwide network of 6 warehouses: Warehouses in Ho Chi Minh City, Ba Ria-Vung Tau, Dong Nai, Da Nang, Can Tho, and Bac Ninh. 24-hour delivery to industrial parks.
3. COA/MSDS for Each Batch: Each batch shipped includes a COA (actual modulus, density, viscosity, solids content) and an MSDS/SDS.
4. Technical Consultation: Assistance in selecting the optimal modulus, advice on curing methods, and recommendations for suitable equipment for each application.
Frequently Asked Questions About Sodium Silicate
Are Sodium Silicate and Liquid Glass the Same Thing?
Yes. “Water glass” is the common trade name for Sodium Silicate (Na₂SiO₃) in solution form. In the industry, these two terms are used interchangeably. Official CAS Number: 1344-09-8.
What is the modulus? Why is it important?
The modulus is the molar ratio of SiO₂ to Na₂O in the Na₂SiO₃ molecule. The modulus determines all properties: solubility, viscosity, setting speed, and bonding ability. For example: a modulus of 2.0 dissolves quickly and has high alkalinity—suitable for cleaning; a modulus of 3.3 provides strong adhesion and cures well with CO₂—suitable for paper tubes and ceramics.
How does Na₂SiO₃ differ from NaOH?
NaOH is a simple alkali — it only provides OH⁻. Na₂SiO₃ has both alkaline properties and the ability to form a SiO₂ gel upon curing — so it is used as a binder and waterproofing agent. Na₂SiO₃ cannot replace NaOH for simple pH adjustment, and NaOH cannot replace Na₂SiO₃ for bonding.
Is Na₂SiO₃ toxic?
Na₂SiO₃ is alkaline (pH 11–13) and can irritate the skin and eyes. It is not toxic in the sense of being a chemical poison, but PPE is required when handling it. After it has fully cured (reacting with CO₂), the product becomes inert and non-toxic.
Where to buy sodium silicate, and how to choose the modulus?
Purchase from a supplier that provides a Certificate of Analysis (COA) clearly stating the actual modulus. Submit your specific application for advice on the appropriate modulus. Loc Thien Chemicals — with 6 warehouses nationwide — supplies Na₂SiO₃ in various moduli; receive a B2B quote within 15 minutes via hotline 0979 891 929.
Get a Sodium Silicate Quote in 15 Minutes
Need Na₂SiO₃ for adhesives, ceramics, construction, or wastewater treatment? Get a fast, accurate quote with complete documentation.
Hotline: 0979 891 929 | Website: hoachatlocthien.com
Please have the following ready: desired modulus · estimated quantity · delivery location · specific application.
Commitment: quote within 15 minutes · COA/MSDS per batch · on-time delivery · technical support.
LOC THIEN INVESTMENT AND DEVELOPMENT CO., LTD.
- Address: 452/6B Provincial Road 10, Binh Tri Dong Ward, Binh Tan District, Ho Chi Minh City
- Phone: 028 6269 5669 - 028 6269 5662
- Hotline: 0979 891 929
- Website: hoachatlocthien.com