Imagine your home, your workplace, or even a tunnel, suddenly engulfed in flames. Terrifying, right? What if there was a way to significantly slow down or even prevent that fire from spreading, buying precious time for escape and rescue? That’s the promise of fire-blocking chemicals, and they’re rapidly changing how we think about building safety.
This article dives into the world of these innovative substances, exploring how they work, what they’re made of, and the potential impact they could have on our lives. Let’s start with an intriguing example: a flame retardant for wood called Burnblock.
Our story begins with a peek inside a vat of clear liquid. Stephen McCann, a manager at Halt, a wood treatment company, jokingly claims you could drink it—though he strongly advises against it due to its intense saltiness. This liquid contains Burnblock, a substance demonstrated to prevent wood from catching fire in controlled tests. To illustrate its effectiveness, Halt shared a compelling video showcasing two model houses being blasted with a blowtorch. One, treated with a standard product, succumbed to flames and collapsed. But the Burnblock-treated model? It only experienced charring in one area, remaining largely intact.
So, what exactly is Burnblock? And this is the part most people miss… The exact composition is shrouded in secrecy. Neither Mr. McCann nor Hroar Bay-Smidt, the CEO of Burnblock, a Danish company, are willing to divulge the specific ingredients. However, documentation from the Danish Technological Institute hints that the active flame-retardant is “a natural component in the body,” combined with citric acid and “a natural component in some berries.” It’s a bit like a magician refusing to reveal their secrets, isn’t it?
Now, flame retardants themselves aren’t new. They’ve been around for centuries, designed to slow down the burning process. But here’s where it gets controversial… Many of the flame retardants developed in the 20th century are now known to be highly toxic. These older chemicals have been linked to various health problems, raising serious concerns about their use. As Alex Morgan, a chemist and flame retardant expert at the University of Dayton Research Institute, points out, there hasn’t been much investment in developing safer alternatives until recently. Now, a scramble is underway to find replacements that protect us without harming us.
Burnblock works by creating a protective char layer on the wood’s surface when exposed to fire, as explained by Mr. Bay-Smidt. This layer acts as a barrier, preventing the flames from reaching the wood itself. Additionally, the substance releases water vapor, which absorbs heat and further slows the fire’s spread. Critically, it also deprives the fire of oxygen, a crucial element for combustion. Burnblock isn’t limited to wood; it can also be applied to other building materials, like dried seagrass, expanding its potential applications.
Halt, the Belfast-based company, has been using Burnblock for nearly four years, supplying treated wood products to numerous locations across the UK and Ireland, including restaurants, hotels, and even the HS2 high-speed rail project, where it was used for treated hoardings in tunnels. McCann emphasizes that in case of fire, these hoardings would provide valuable evacuation time. To date, none of the buildings or facilities using Halt’s Burnblock-treated wood have experienced a fire.
The magic happens inside a massive machine called an autoclave. This device uses a vacuum to open up the wood’s pores, followed by pressure to force the fire retardant deep into the timber’s core. The pressure used depends on the type of wood being treated. Afterward, the wood is carefully dried in a kiln, a process that can take anywhere from 10 days to six weeks. Slow and steady wins the race here; rapid drying can warp the wood, compromising its structural integrity.
Richard Hull, a fire retardants expert at the University of Lancaster, highlights wood’s unique ability to absorb treatment fluids within its pores, allowing for a change in its burning behavior. But, he remains cautiously skeptical of new flame retardants. He notes that many promising ideas, like clay nanocomposites in the early 2000s, ultimately faded away. We need to proceed with optimism, tempered by scientific rigor.
While making timber fire-resistant is relatively straightforward due to its consistent burning rate, making plastics flame-resistant presents a greater challenge. Plastics tend to burn at an accelerating rate. Dr. Morgan even refers to polyethylene, a common plastic used in construction, as “solid gasoline” due to its highly flammable nature.
In Australia, First Graphene claims to have found a solution for slowing fire spread in plastics by adding graphene – tiny flakes of carbon atoms arranged in honeycomb lattices. Their product, PureGRAPH, is already being used in protective footwear and conveyor belts in the mining industry. First Graphene believes PureGRAPH creates a protective gas barrier that prevents the release of volatile compounds before ignition and also forms a char layer if ignition occurs. However, graphene is a relatively new and complex material, and the company acknowledges that other, yet-to-be-understood mechanisms may also be at play.
But, could graphene pose health risks in the event of a fire? A spokeswoman for First Graphene assures that current data suggests no health hazards associated with graphene. However, she emphasizes that the industry is continuing to test and evaluate these aspects. In the UK, Vector Homes is preparing to license PureGRAPH to manufacturers of plastic pellets for construction materials like fascia boards, indicating growing interest in this technology.
Experiments have shown that graphene does indeed reduce the flammability of plastic, achieving top ratings in fire resistance tests, according to Liam Britnell, co-founder and chief technology officer at Vector Homes.
However, the threat of fire doesn’t just come from internal sources. Wildfires are on the rise, posing a significant risk to buildings. Eric Appel at Stanford University and his team are developing gel-like fire retardants that can be sprayed onto homes hours before a wildfire arrives, providing a protective barrier. During lab tests, one of Appel’s gels bubbled up upon exposure to flame, forming a porous aerogel structure that offered excellent fire protection. He hopes to test this substance on mini-structures or mock-built homes soon.
These are just a few examples of the exciting innovations happening in the world of fire-blocking chemicals. As we face increasing fire risks, the development and implementation of these technologies are becoming more critical than ever. What do you think? Are these new fire-retardant technologies a promising solution to increasing fire risks, or do you have concerns about their long-term safety and effectiveness? Share your thoughts in the comments below!