Intumescent hybrid coating protects wood by ceramic charring

Chinese researchers have developed a new type of organic-inorganic, intumescent coating to improve the fire protection of wooden surfaces. The formulation is based on a modified amino resin (PMFG), which was further reacted with tannic acid (TA) and phytic acid (PA) to form a resin (PTP) containing nitrogen and phosphorus. The system was supplemented with glass powder (GP) or silicon dioxide (SiO₂) to promote ceramic charring during firing. The application was carried out in layers on wooden substrates.

When exposed to fire, the coating forms a foamy, lava-like expanding ceramic layer that effectively shields the wood from the effects of flames. The Limit Oxygen Index (LOI) was 49.8 – a very high value for wood substrates.

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Significant reduction of smoke and heat

Compared to the unmodified PTP coating, the optimal hybrid structure was able to reduce the total heat release (THR) by 78.77%, smoke production (TSP) by 78.88% and CO release by 41.67%. The research shows how cost-effective materials can be used to significantly improve fire safety in timber construction – particularly with regard to smoke toxicity and thermal stress.

The coating presented offers a promising solution for modern, sustainable construction concepts in which wood is used as a material – without compromising on safety.

Source: Progress in Organic Coatings, Volume 200, March 2025, 109037

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