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Engineering news

‘Invisible’ coating protects construction timber from fire

Professional Engineering

Associate Professor Aravind Dasari and PhD student Dean Seah test the coated timber in the lab (Credit: NTU Singapore)
Associate Professor Aravind Dasari and PhD student Dean Seah test the coated timber in the lab (Credit: NTU Singapore)

A new coating can fireproof wood without any visible impact on the material, its creators have said.

Aimed at enabling widespread use of mass engineered timber in construction, the coating was developed by scientists at Nanyang Technological University, Singapore (NTU Singapore).

Mass engineered timber has gained popularity over the last decade due to lower costs and faster construction, which offers productivity gains of up to 35%. If the wood is harvested from sustainably managed forests, it also has a lower carbon footprint compared to steel or concrete buildings.

Current practices to protect the interior of wooden buildings from fire require fire-retardant panels such as gypsum and magnesia boards, or coating the timber with paint-like fire-retardant coatings, both of which conceal the natural wood grain of the timber.

The new coating “allows for [the] natural beauty of timber to shine” while providing protection from fire, the researchers said.

Invented by a team led by associate professor Aravind Dasari from the NTU School of Materials Science and Engineering, the coating is 0.075mm thick and is highly transparent, making it invisible to the naked eye.

When heated by flames a series of complex chemical reactions happen, causing the coating to become a char that expands to more than 30-times its original thickness. The char prevents the fire from combusting the wood underneath.

“Most timber or wooden panels only have a transparent coat that protects them from moisture, weather corrosion, termites or pests, and are not designed to withstand high heat. Thus, timber can still burn very quickly, especially if it is unprotected,” said Dasari.

“In our coating, we used technology to lock certain compounds and interact with the resin. They will actively participate in the chemical reactions in a systematic manner when exposed to high heat, thus leading to the formation of char. This char was engineered to be extremely heat-resistant, insulating the wood underneath from the high heat.”

A spokesman for NTU told Professional Engineering that they were unable to share further details about the coating’s ingredients or formula for intellectual property reasons, but said that the coating can be applied in various ways, including spray painting, brush painting, roller painting, and screeding, or spreading it over the surface. After application, it needs to cure for a day.  

The team is now in licensing talks with different companies. Local firm Venturer Timberwork is exploring the use of the coating to protect mass engineered timber elements in one of its current projects.

“There are only a few products that can provide both transparency and fire retardance that are available in the market. Products which claim to have both properties currently are either extremely prohibitive in cost or are unable to pass international standards required for industrial use,” the researchers said.

In industry-standard tests, such as ‘single burning item’ tests at a third-party accreditation laboratory, the NTU coating reportedly achieved the highest class possible. When exposed to a high-temperature flame, the coating generated very little smoke and was able to prevent the flames from spreading. When the char was scraped off the wood underneath was still intact, proving the efficiency of the coating in protecting the wood. 

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Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.


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