Differences Between Magnesium Oxysulphate (MgSO₄) & Magnesium Oxychloride (MgCl₂) MGO Boards
Jan 22, 2026
Core Conclusion: Magnesium Oxysulphate (MgSO₄) MGO boards are an upgraded alternative to Magnesium Oxychloride (MgCl₂) MGO boards. The root difference lies in their binder formulations, with core gaps concentrated in four dimensions: halogen return/moisture sweating, steel structure corrosion, weather resistance, and application scenarios. MgSO₄ boards solve the fatal pain points of MgCl₂ boards, making them the preferred choice for high-demand construction projects.
1. Core Formulation Differences (Root Cause)
Magnesium Oxychloride (MgCl₂) Board: Uses magnesium chloride (MgCl₂) as the core binder, which reacts with magnesium oxide (MgO) to form magnesium oxychloride cement – the traditional MGO board formulation.
Magnesium Oxysulphate (MgSO₄) Board: Uses magnesium sulfate (MgSO₄) as the core binder, which reacts with magnesium oxide (MgO) to form magnesium oxysulphate cement – an improved high-end formulation.
2. Halogen Return & Moisture Sweating (Most Critical Pain Point Difference)
MgCl₂ Board: Prone to moisture absorption and halogen return ("sweating") – magnesium chloride has extremely high hygroscopicity. In high humidity or with condensed water, it precipitates white halide salt crystals on the board surface, causing stickiness, finish contamination, and even impaired adhesion of waterproofing/decorative layers.
MgSO₄ Board: No halogen return or moisture sweating – magnesium sulfate has far lower hygroscopicity than magnesium chloride, keeping the board surface dry at all times. It completely eliminates the "sweating" issue and is suitable for damp/high-humidity environments.
3. Steel Structure Corrosion Risk (Key Safety Difference)
MgCl₂ Board: Contains chloride ions, highly corrosive – chloride ions corrode steel trusses, light steel keels, and metal fasteners. Long-term use easily leads to steel structure rust and structural loosening, strictly prohibited for steel-structured buildings.
MgSO₄ Board: No chloride ions, zero corrosion – the formulation contains no corrosive ions and is compatible with steel structures/metal components. It is the only compliant choice for steel-structured buildings, light steel villas, and roof steel purlin scenarios.
4. Water Resistance & Weather Resistance (Performance Difference)
| Performance | Magnesium Oxychloride (MgCl₂) Board | Magnesium Oxysulphate (MgSO₄) Board |
|---|---|---|
| Water Resistance | Poor; softens, delaminates, and loses strength drastically when soaked in water | Excellent; water absorption rate ≤12%, no delamination/softening after 72h water immersion |
| Freeze-Thaw Resistance | Poor; prone to cracking under freeze-thaw cycles | Excellent; passes 50+ freeze-thaw cycle tests |
| Salt Spray/Coastal Adaptability | Poor; prone to moisture-induced corrosion | Excellent; adapts to coastal high-salt spray and high-humidity environments |
5. Application Scenarios (Core Basis for Selection)
Magnesium Oxychloride (MgCl₂) Board: Only suitable for dry, low-demand, non-steel-structured indoor scenarios (e.g., ordinary indoor partition walls, suspended ceilings, temporary partitions). Low cost but with extreme limitations.
Magnesium Oxysulphate (MgSO₄) Board: Suitable for all high-demand, extreme environment scenarios (e.g., roof sheathing, flooring substrates, basements, steel-structured buildings, coastal/high-wind/frigid regions, data centers/hospitals and other high-fire-safety projects). Its comprehensive cost-performance ratio far exceeds that of MgCl₂ boards.
6. Cost & Service Life (Economic Difference)
MgCl₂ Board: Low raw material cost, but short service life (10–20 years). Prone to halogen return, corrosion, and cracking, resulting in high later maintenance/replacement costs.
MgSO₄ Board: Slightly higher raw material cost, but service life ≥50 years. No halogen return, corrosion, or weather resistance degradation, with zero later maintenance and lower total life cycle cost.
Selection Summary
For low-cost, dry indoor, non-steel-structured temporary/low-demand projects: Magnesium Oxychloride (MgCl₂) boards can be selected;
For long-term durability, damp/steel-structured/coastal/high-fire-safety projects: Magnesium Oxysulphate (MgSO₄) boards are a must – the mainstream high-end choice for MGO boards.
