Fire-resistant, IR-reflective and halogen-free finishes

As a functional filler, magnesium chemistry does double duty in a coating: it carries the fire performance and improves the optical and barrier properties of the film at the same time. Among the common flame-retardant fillers, Mg(OH)₂ consistently delivers the lowest backside temperature with the least damage to the substrate.

01MgO as a functional filler

Beyond fire performance, MgO brings whiteness, high infrared reflectance and mild alkalinity to a formulation. Those three properties make it a natural fit for two very different product families:

• Intumescent & fire-resistant coatings. MgO reinforces the char structure, so the intumescent layer stays coherent instead of cracking and falling away.

• IR-reflective and camouflage finishes. High-NIR-reflectance pigments keep surfaces cooler and help a coating blend into the infrared background.

• Corrosion control. Mild alkalinity neutralises acidic species at the film–metal interface and stabilises the coating over time.

02Mg(OH)₂ in halogen-free FR coatings

Where a coating must protect a steel structure, a ship bulkhead or a cable tray, Mg(OH)₂ is the filler of choice. It releases water endothermically at 300–320 °C, so the coating cools the substrate exactly when the fire arrives, and the MgO residue left behind is itself refractory.

Because it contains no halogen, there is no acid gas to corrode the very steel it was protecting — a real advantage over halogenated systems in marine and industrial environments.

03Getting the dispersion right

Water-based formulations are where Mg(OH)₂ really shines: it disperses readily without organic solvents, and surface-treated grades resist settling and viscosity build-up during storage. For solvent-based systems, a stearate or silane treatment keeps the filler compatible with the resin and lowers the oil absorption.

04Recommended grades