Not All MgO Boards Are Created Equal: Magnesium Oxysulfate vs. Magnesium Oxychloride

Why NOCOM & M4 Panels Deliver True Chloride-Free Confidence

In today’s construction environment, durability isn’t optional. When panels fail, hidden corrosion can compromise steel framing, fasteners, and plumbing leading to costly repairs and liability years down the road.

Multi-Panels has engineered our product line, including NOCOM® Structural Subfloor, M4® Underlayment, and M4® Wall Sheathing, with one goal in mind: eliminate the risk of corrosion at its source.

NOCOM Structural Subfloor is ideally suited for steel framed construction

The Formula Matters: MgSO₄ vs. MgCl₂

Not all “MgO boards” are created equal. Many of the corrosion-related failures reported were caused by low-quality magnesium oxychloride (MgCl₂) boards, which may leach chloride salts under humidity (“crying” or “sweating”). That chloride migrates to metal fasteners, framing and other metals causing accelerated corrosion.

NOCOM & M4 are based on magnesium oxysulfate (MgSO₄) cement, a chloride-free formulation that:

• Contains no corrosive chlorides

• Prevents the “crying” phenomenon that may occur with poorly made MgCl₂ products

In simple terms: no chlorides, no corrosion.

Lab Tested & Field Proven: Corrosion Resistance You Can Trust

We don’t just make claims, we’ve backed them up with lab tests:   

• ASTM C665 Corrosion Testing – Multi-Panels proprietary MgSO4 formulation was tested per ASTM C665 to the prescribed 96-hours exposure and beyond. 

  • Steel, Aluminum & Copper – 96-hours

  • Steel extended to 720 hours – just to make absolutely sure

  • Results: PASS on all metals. Test coupons showed no statistical difference compared to clean control samples - proof that our boards are truly non-corrosive.

• While lab tests and reports are important, we feel the best testimony is the customer.  And in this case silence is golden.  In the millions of square feet of NOCOM & M4 panels installed in the United States we have ZERO complaints of corrosion. 

Premium Manufacturing: When Precision Matters

• Modern facility, precise processes

  Our lines employ automated metering, mixing, curing, and conveying systems. This ensures consistent mix quality and reproducibility even under high-volume demand.

• Carefully staged drying and trimming

  Panels undergo two-phase curing: hot, low-humidity initial cure followed by extended controlled conditioning before sizing and sanding preventing internal flaws or moisture-induced reactions.

• Two-tier QC with batch verification

  Every shipment is verified at both manufacturer and distribution levels. We “trust but verify” to guarantee each board meets performance benchmarks and maintains integrity in transit.

Real Benefits for Building Projects

Benefit	What It Means for Your Builds
Non-Corrosive Assurance	No chloride means no salt-induced corrosion — preserving fasteners, framer connections, and system longevity.
Moisture Resistance	Stable panels in humid zones avoid “weeping” or compromising adjacent materials.
Durability & Stability	Consistent material behavior from installation to service life — fewer surprises, less liability.
Traceable Quality	Batch-level QC and transparent sourcing provide confidence in performance and legal solid ground.

A Responsible, Forward-Looking Investment

We don’t cut corners. Our boards reflect a commitment to quality, safety, and reliability. By choosing M4 / NOCOM MgSO₄ raw materials and premium manufacturing protocols, you're investing in:

• A non-corrosive substrate engineered for demanding environments

• Predictable performance backed by rigorous testing and validation

• A well-documented process that supports code compliance and builds trust

Final Thoughts

M4 / NOCOM MgSO₄-based boards are more than an alternative to traditional MgO products, they set the new standard in non-corrosive, moisture-resistant construction materials. With purposeful engineering, premium inputs, and uncompromising QC, they protect underlying metal assemblies and support long-term building integrity.

Let’s talk about how this can elevate your next project, whether you're specifying for coastal conditions, high-humidity interiors, or fire-rated assemblies.