A clear liquid, a specialized flame retardant for wood products, is being developed. Stephen McCann, general and technical manager at Halt, a Belfast-based wood treatment company, stated that the liquid is safe enough to drink, though he wouldn’t recommend it due to its salty taste. This liquid, which contains Burnblock, has demonstrated its ability to prevent wood from catching fire in various tests.
A demonstration video
showed two model houses subjected to a blow torch. One house, treated with a different product, quickly became engulfed in flames and collapsed. In contrast, the Burnblock-treated model only charred in one corner, remaining largely intact.
The exact composition of Burnblock remains undisclosed by both Mr. McCann and Hroar Bay-Smidt, CEO of the Danish firm Burnblock. However, documentation from the Danish Technological Institute on Burnblock’s website indicates that the flame retardant ingredient is a ‘natural component in the body,’ and the mixture also includes citric acid and a ‘natural component found in some berries.’
Flame retardants, which are chemicals designed to slow down the burning process of products, have existed in various forms for centuries. Many 20th-century flame retardants are known to be highly toxic. Alex Morgan, a chemist and flame retardant expert at the University of Dayton Research Institute in the US, noted that a lack of investment in replacements has led to a sudden rush to find new solutions.
Mr. Bay-Smidt explained that when Burnblock-treated wood is exposed to fire, it forms a protective char layer. The substance also releases water, which helps absorb heat and slows the fire’s progression by preventing oxygen from fueling the flames. Burnblock can be applied to various building materials, including dried seagrass.
Halt, a company operating in Belfast for almost four years, has provided Burnblock-treated wood products to numerous sites across the UK and Ireland, including restaurants, hotels, and the HS2 project. For HS2, Halt supplied treated hoardings for tunnel construction areas. Mr. McCann highlighted that evacuation from tunnels can be challenging, necessitating maximum time in case of fire. He confirmed that no buildings or facilities constructed with Halt’s treated wood have experienced a fire to date.
Within one of Halt’s facilities, a large autoclave machine processes wood. This machine, primarily composed of two horizontal tubes, uses a vacuum to open the wood’s pores when loaded with timber, as explained by Mr. McCann. Following the vacuum process, the treatment fluid is applied under pressure, adjusted according to the specific wood species. Mr. McCann explained that this pressure forces the fire retardant deep into the timber’s core.
Subsequently, the wood undergoes a drying process in a large kiln, which can take between 10 days and six weeks. This process is meticulously managed to prevent warping caused by improper drying speeds.
Richard Hull, professor emeritus and fire retardants expert at the University of Lancashire, described timber as an ‘amazing material,’ noting its capacity to absorb treatment fluids into its pores. He stated that this allows for a fundamental alteration of its burning characteristics.
Despite the potential, Hull often expresses skepticism regarding new flame retardants, observing that many concepts have not endured. He cited extensive work on clay nanocomposites in the early 2000s, noting that ’20-25 years later, essentially 99% of that has fizzled out.’
While timber typically burns at a consistent rate, making plastic flame resistant presents a different challenge, as plastics tend to burn at an accelerating pace. Dr. Morgan referred to polyethylene, a common construction plastic, as ‘solid gasoline’ due to its chemical structure and rapid burning capability.
In Australia, First Graphene claims to have developed a method to slow fire spread in plastics by incorporating graphene, which are minute flakes of carbon atoms arranged in honeycomb lattices. Michael Bell, the managing director and chief executive, stated that their solution, PureGRAPH, is already utilized in products like protective footwear and mining conveyor belts.
First Graphene explains that PureGRAPH functions by creating a protective gas barrier, which inhibits the release of volatile compounds before ignition, and also forms a char layer if ignition occurs. However, graphene’s complex nature suggests that other, not yet fully understood, mechanisms might also be involved.
Regarding potential health effects of graphene after a fire, a spokeswoman indicated that ‘There’s no data suggesting that graphene poses any health hazards,’ adding that the industry is continuously testing and evaluating these aspects.
In the UK, Vector Homes plans to license PureGRAPH to manufacturers of plastic pellets, which could then be used in construction materials like fascia boards. Experiments indicate that graphene effectively reduces plastic’s flammability. Liam Britnell, co-founder and chief technology officer, noted that it achieves ‘the highest ratings in those tests.’
Buildings face risks not only from internal fires but also from an increase in wildfires, as highlighted by Dr. Morgan. This concern has led Eric Appel and his colleagues at Stanford University to develop gel-like fire retardants that could be sprayed onto homes hours before a wildfire, thereby mitigating damage.
Professor Appel intends to test this substance on miniature structures or mock-built homes in the near future. Laboratory research showed that one of the gels, when exposed to a flame, expanded to form a porous aerogel structure internally, offering significant fire protection. Professor Appel recalled his immediate reaction upon observing this phenomenon: ‘As soon as I saw that it did that, it was like, ‘Oh my gosh – that would be perfect for this.”
