Magnesium oxide boards, commonly known as MgO boards, have gained global recognition in recent years as a next-generation building material that offers outstanding fire resistance, moisture resistance, and environmental safety. But how is MgO board made, and what gives it such exceptional performance? The answer lies in its unique composition and precise manufacturing process. This article provides a detailed overview of the raw materials, production techniques, and post-treatment steps involved in making MgO boards, helping builders, architects, and buyers better understand why MgO is becoming a preferred alternative to traditional gypsum and cement-based panels.
Composition & Raw Materials
Magnesium oxide (MgO) boards are high-performance construction materials that have become increasingly popular for their superior fire resistance, moisture protection, and environmental sustainability. The exceptional properties of MgO boards are not accidental—they are the result of a precise formulation involving six key raw materials, each contributing specific performance benefits. Understanding these ingredients is crucial to appreciating why MgO boards are such an effective and reliable building solution.
1. Magnesium Oxide (MgO) Powder
At the heart of every MgO board lies magnesium oxide powder. This fine, non-toxic, and inorganic material is derived from calcined magnesite—a process that involves heating magnesite to remove carbon dioxide, producing a reactive oxide. MgO powder is the primary cementitious component in the board, offering excellent compressive strength and exceptional fire resistance. When blended with magnesium sulfate or magnesium chloride in an aqueous environment, it undergoes a rapid chemical reaction that forms a solid, stone-like matrix. This hardened matrix serves as the structural backbone of the board.
2. Magnesium Sulfate (MgSO₄) or Magnesium Chloride (MgCl₂)
These two salts function as the key activators or binders in the board’s matrix. Magnesium sulfate usually appears as a white crystalline powder, while magnesium chloride is typically a colorless, flaky solid. When either of these salts is mixed with MgO powder and water, they initiate a complex exothermic reaction that transforms the slurry into a hard, stable material. The choice between magnesium sulfate and magnesium chloride has implications for the board’s performance and long-term durability.
- Sulfate-based boards (MgO sulfate boards) are known for their enhanced water resistance and lower risk of corrosion.
- Chloride-based boards (MgO chloride boards) offer quicker setting times and are widely used but often require additional processing to prevent long-term chemical degradation (as addressed in the soaking process).
3. Perlite
Perlite is a naturally occurring volcanic rock that, when heated, expands to form lightweight, porous granules. In MgO boards, it acts as a functional filler. Its inclusion reduces the overall weight of the board while simultaneously enhancing thermal insulation and fireproofing characteristics. Perlite also helps improve the board’s dimensional stability under temperature fluctuations.
4. Fiberglass Mesh
Fiberglass mesh is a woven reinforcement material made from fine glass fibers. This mesh is embedded within the board structure and plays a crucial role in enhancing tensile strength and impact resistance. It helps the board maintain integrity under mechanical stress and prevents cracking during handling, installation, or exposure to temperature changes.
5. Non-Woven Fabric
This layer, often made of polyester (PET) fibers through needle-punching techniques, is applied on the board surface to improve smoothness and consistency. It also acts as a bonding layer that enhances adhesion between the layers of the board. Non-woven fabric contributes to water resistance, flame retardancy, and helps reduce the risk of surface peeling over time.
6. Wood Fiber
Also referred to as sawdust or wood flour, wood fiber is incorporated as a lightweight natural filler. It not only helps reduce the density of the board but also improves workability, making the board easier to cut and install. Wood fiber adds to the board’s acoustic insulation properties and helps minimize shrinkage and cracking during curing.
Why These Materials Matter
- Fire Resistance: The synergy between magnesium oxide and perlite enables the board to withstand high temperatures. Many MgO boards meet EN13501 Class A1 fire ratings, making them suitable for fire-critical applications.
- Moisture and Mold Resistance: The use of inorganic, non-hygroscopic materials ensures minimal water absorption and prevents mold or fungal growth.
- Sustainability: All ingredients are asbestos-free, contain no VOCs, and are safe for indoor air quality.
- User-Friendly Installation: Thanks to the combination of low weight and high strength, MgO boards are easier to handle than traditional alternatives like cement board or gypsum board.
How is mgO Board Made
The manufacturing process of magnesium oxide boards is a carefully controlled series of steps that transform raw materials into durable, multifunctional construction panels. Each stage plays a vital role in achieving the board’s structural performance, fire safety, and longevity.
1. Material Preparation
The process begins with precise batching of the raw materials based on a proprietary formula. Accurate proportions of MgO powder, magnesium salts (sulfate or chloride), perlite, wood fiber, and water are measured to ensure consistent quality. The dry and wet components are often prepared separately to prevent premature reactions.
2. Mixing
Next, all ingredients are transferred into an industrial mixer. This high-efficiency equipment ensures thorough blending of the dry and wet materials, forming a homogeneous slurry. Uniformity at this stage is crucial, as it affects the board’s strength, setting time, and final finish.
3. Board Formation
The mixed slurry is continuously poured onto a production line where non-woven fabric and fiberglass mesh are layered in. These reinforcement materials are embedded into the slurry to enhance dimensional stability and surface integrity. The slurry is spread to the required thickness using leveling rollers or automated screed bars.
4. Curing Phase I
Immediately after shaping, the fresh boards enter a controlled curing environment where temperature and humidity are optimized to initiate the setting reaction. This phase typically lasts several hours and allows the chemical bonds to form, giving the board its initial strength.
5. Demolding
Once the boards have reached sufficient rigidity, they are removed from their templates using a demolding machine. Careful handling at this stage is essential to avoid warping or surface damage.
6. Curing Phase II
After demolding, the boards continue to cure at ambient temperatures. During this phase, which can last up to seven days, residual chemical reactions complete, and the board gains its final mechanical properties. Heat generation from the curing reaction may be monitored to ensure consistency.
7. Optional Soaking (for MgO Chloride Boards)
For boards produced with magnesium chloride, an additional soaking process may be applied. This involves immersing the boards in water pools to leach out excess chloride ions, which can otherwise lead to corrosion of embedded metals or reduced lifespan. This optional step significantly improves the board’s long-term durability and structural compatibility.
8. Drying
The soaked or cured boards are then dried—either in natural sunlight or through industrial drying systems—until they reach optimal moisture content. Proper drying ensures dimensional stability and prevents issues like warping or delamination.
9. Cutting
In the final stage, the dried boards are cut to desired sizes using precision cutting machines. Custom sizes and edge treatments can be applied based on application needs, such as tongue-and-groove edges or beveled corners.
Difference Between MgO Chloride Boards and MgO Sulfate Boards
When exploring how MgO board is made, one of the most critical distinctions lies in the type of chemical binder used—magnesium chloride (MgCl₂) or magnesium sulfate (MgSO₄). These two variations result in different types of MgO boards: MgO chloride boards and MgO sulfate boards. Although both share a base of magnesium oxide and are known for being eco-friendly and fire-resistant, they exhibit significant differences in performance, stability, and long-term application.
1. Chemical Composition and Stability
- MgO Chloride Boards are produced using magnesium chloride, a hygroscopic salt that can absorb moisture from the environment. This property can sometimes lead to “sweating,” surface crystallization, or corrosion when the boards come into contact with metal elements such as steel studs or screws.
- MgO Sulfate Boards, on the other hand, use magnesium sulfate, which is chemically more stable. Sulfate-based boards do not contain chloride ions, so they present no risk of corrosion, making them a better choice for long-term use, particularly in high-humidity environments or with metal-framed constructions.
2. Water Resistance and Durability
Both types of MgO boards are water-resistant, but sulfate boards typically perform better under long-term moisture exposure. MgO sulfate boards are less prone to efflorescence (the appearance of salt crystals on the board surface) and maintain dimensional stability better over time.
Chloride boards may require post-processing such as soaking or chemical treatment to reduce free chloride ions and ensure product longevity.
3. Corrosion Risk and Structural Compatibility
If you’re building a structure with steel framing, electrical systems, or any metal-based components, MgO sulfate boards are the safer and more reliable option. Chloride ions from MgO chloride boards can corrode metal over time unless the board has undergone chloride-removal processes such as water soaking. This makes sulfate boards a preferred material in export markets with strict construction safety codes.
4. Manufacturing Process and Cost
- MgO Chloride Boards are easier and cheaper to produce, which makes them more common in domestic markets where cost sensitivity is high.
- MgO Sulfate Boards, while more complex to manufacture due to the need for precise curing and high-purity materials, offer higher long-term value. They are often chosen for premium, long-lasting applications where durability and performance are non-negotiable.
5. Applications and Market Preference
- MgO Chloride Boards are often used in interior walls, partitions, ceilings, and temporary construction, especially in cost-sensitive projects where exposure to moisture and corrosion is minimal.
- MgO Sulfate Boards are favored in high-performance buildings, export projects, bathrooms, kitchens, tunnels, and humid regions, where safety, stability, and durability are paramount.
6. Environmental and Regulatory Considerations
From an environmental standpoint, both boards are non-toxic and asbestos-free. However, MgO sulfate boards are increasingly favored in regions such as Europe, North America, and Australia due to their compliance with international standards on indoor air quality, moisture control, and corrosion resistance.
7. Soaking Process: A Key Step for Chloride-Based Boards
One of the most notable differences in how MgO board is made lies in the post-processing stage. Specifically, MgO chloride boards often undergo a soaking process—submerging the boards in water tanks for several hours or even days. This optional yet important step helps to remove excess chloride ions from the board structure.
Why is this necessary? Without soaking, residual chloride ions may continue to migrate to the board surface over time, especially in humid conditions. This can lead to:
- Surface crystallization (efflorescence)
- Reduced structural bonding
- Accelerated corrosion of embedded metals
By soaking the boards, manufacturers can significantly reduce the potential for corrosion, improve long-term dimensional stability, and meet higher building standards—especially for export use or projects requiring metal framing.
In contrast, MgO sulfate boards do not require this soaking step, as sulfate compounds are inherently non-corrosive. This simplifies the production process and improves consistency in product quality.
By understanding the difference between MgO chloride boards and MgO sulfate boards, builders and buyers can make more informed choices that align with the specific requirements of their construction projects. Whether your priority is cost-efficiency, long-term durability, or compatibility with metal structures, selecting the appropriate type of MgO board is essential for maximizing safety and performance.
Installation of MgO Boards
Installing MgO boards is a relatively straightforward process, thanks to their lightweight structure, flexibility, and compatibility with various construction systems. Whether used for wall partitions, ceilings, flooring substrates, or fire-rated assemblies, MgO boards offer a cleaner, safer, and faster installation compared to traditional materials like gypsum board or fiber cement board.
1. Cutting and Handling
MgO boards can be easily cut using standard construction tools such as utility knives, circular saws with carbide blades, or jigsaws. This eliminates the need for specialized equipment and minimizes dust, making the installation process safer and more environmentally friendly. Boards should be handled with care to avoid edge damage, and protective gloves are recommended.
2. Fastening
The boards can be attached using corrosion-resistant screws, nails, or construction adhesives, depending on the substrate material. When installing on metal frames, self-tapping screws are ideal, while wood frames may use standard drywall screws. Fasteners should be spaced evenly, typically 200–300 mm apart, to ensure a tight and stable fit.
3. Joint Treatment
For interior applications, joints between MgO boards can be sealed using fiberglass tape and joint compound to create a smooth finish. In high-humidity or fire-rated installations, use specialized sealants or fire-rated fillers to maintain the integrity of the system.
4. Surface Finishing
Once installed, MgO boards can be painted, plastered, tiled, or laminated with decorative panels. Thanks to the smooth surface and excellent adhesion properties, MgO boards accept a wide range of finishes without requiring extensive priming.
5. Safety and Compatibility
MgO boards are non-combustible, mold-resistant, and free of harmful substances like formaldehyde or asbestos, making them suitable for hospitals, schools, kitchens, and other sensitive environments. They are also compatible with steel frame systems and modular construction methods.
Packaging, Storage & Transportation
Proper packaging, storage, and transportation of magnesium oxide boards are essential to maintaining their performance and structural quality throughout the supply chain. As an engineered product, MgO boards should be treated with the same care as other high-value building materials.
1. Packaging
MgO boards are typically stacked on wooden or plastic pallets and wrapped with PE film or kraft paper for surface protection. Corner protectors and strapping bands are often added to stabilize the load and prevent edge damage during handling. Some manufacturers also include moisture-absorbing sheets or breathable covers for boards destined for long-distance shipping.
2. Storage Guidelines
Boards should be stored in a cool, dry, and well-ventilated area, ideally indoors. If outdoor storage is unavoidable, make sure the boards are elevated off the ground and fully covered with waterproof sheeting to protect against rain, humidity, and direct sunlight.
Stack boards horizontally and avoid leaning them vertically, as this may cause warping or cracking. It is recommended to limit the stack height to avoid excessive weight on the lower boards.
3. Transportation Considerations
During transportation, especially over long distances or in export scenarios, MgO boards should be protected against impact, moisture, and vibration. Trucks or containers should be clean, dry, and well-secured to prevent movement during transit. For international shipping, using desiccants and shrink wrapping can help control humidity and avoid chloride-based corrosion (especially for MgO chloride boards).
Proper labeling, including board type, size, batch number, and handling instructions, ensures traceability and reduces installation errors on-site.
Conclusion
Magnesium oxide boards are quickly redefining what builders and architects can expect from wall and ceiling materials. Their high fire rating, mold resistance, eco-friendliness, and versatility make them a premium alternative to gypsum and cement-based boards. From the precise selection of raw materials—like magnesium oxide, perlite, and fiberglass mesh—to the carefully managed production and curing processes, every stage contributes to their superior performance.
The ease of installation, minimal maintenance, and long service life further increase their value in both residential and commercial projects. Whether you are building fireproof partitions, moisture-resistant subfloors, or eco-conscious interiors, MgO boards offer a compelling combination of durability, safety, and sustainability.
By understanding how MgO boards are made, and the science behind their composition and processing, construction professionals can make more informed material choices and confidently incorporate MgO into modern building solutions.
If you’re looking for a reliable supplier of high-quality MgO boards or want to learn more about how MgO board is made, feel free to contact us today — our team is ready to assist you.
