Imagine a world where buildings are no longer vulnerable to devastating fires. It sounds like a dream, but innovative fire-blocking chemicals are turning this vision into reality. But here's where it gets controversial: while these chemicals promise safer structures, their long-term environmental and health impacts remain a hotly debated topic. Let’s dive into the fascinating world of fire-retardant technology and explore what it means for the future of construction.
Just recently, I found myself standing in front of a massive vat filled with a crystal-clear liquid—a revolutionary flame retardant designed specifically for wood products. Stephen McCann, the general and technical manager at Halt, a Belfast-based wood treatment company, offered a surprising revelation: 'You can drink it. I have.' He quickly added, 'Though I wouldn’t recommend it—it’s incredibly salty.' This liquid, infused with a substance called Burnblock, has demonstrated remarkable fire-resistant properties in tests.
In a captivating video shared by the company (https://vimeo.com/726687060?fl=pl&fe=ti), two miniature houses are subjected to a blow torch. One, treated with a conventional product, erupts into flames and collapses. The other, treated with Burnblock, sustains only minor charring in one corner, remaining largely intact. And this is the part most people miss: the exact composition of Burnblock remains a closely guarded secret. Neither McCann nor Hroar Bay-Smidt, CEO of the Danish firm Burnblock, will disclose its ingredients. However, documentation from the Danish Technological Institute hints that it contains 'a natural component found in the human body,' citric acid, and 'a natural component in some berries.'
Flame retardants, chemicals designed to slow down combustion, have been in use for centuries. However, many 20th-century formulations are highly toxic, raising serious health concerns (https://theconversation.com/flame-retardant-chemicals-can-cause-serious-health-risks-and-they-only-slow-fire-by-a-few-seconds-214658). 'The lack of investment in safer alternatives has left us scrambling to find replacements,' explains Alex Morgan, a chemist and flame retardant expert at the University of Dayton Research Institute in the U.S.
When wood treated with Burnblock is exposed to fire, it forms a protective char layer and releases water, which absorbs heat and slows the fire’s spread. This process also deprives the flames of oxygen. Burnblock can be applied to various building materials, including dried seagrass, according to Bay-Smidt.
Halt, operating in Belfast for nearly four years, has supplied Burnblock-treated wood to hundreds of sites across the UK and Ireland, from restaurants and hotels to major projects like HS2. For HS2, Halt provided treated hoardings to fence off construction areas in tunnels. 'In the event of a fire, every second counts for evacuation,' McCann emphasizes. Remarkably, none of the buildings or facilities using Halt’s treated wood have experienced a fire to date.
At Halt’s facility, a massive machine called an autoclave plays a crucial role. It consists of two large horizontal tubes: one filled with the treatment fluid and the other for the wood. The wood is first exposed to a vacuum to open its pores, then subjected to pressure and the treatment fluid, forcing the fire retardant deep into the timber’s core. The wood is then dried in a kiln over 10 days to six weeks, a process carefully managed to prevent warping.
'Timber is an extraordinary material,' says Richard Hull, professor emeritus and fire retardants expert at the University of Lancaster. 'Its porous structure allows it to absorb treatment fluids, fundamentally altering its burning behavior.' However, Hull remains skeptical of new flame retardants, noting that many promising ideas, like clay nanocomposites in the early 2000s, have faded over time.
While timber burns at a relatively consistent rate, making plastic flame-resistant is far more challenging due to its accelerating burn rate. Dr. Morgan describes polyethylene, a common construction plastic, as 'solid gasoline' because of its rapid combustibility.
In Australia, First Graphene claims to have found a solution by adding graphene—tiny carbon flakes—to plastics. Their product, PureGRAPH, has been incorporated into protective footwear and mining conveyor belts. It works by forming a protective gas barrier and a char layer upon ignition. However, graphene’s properties are not fully understood, and its long-term health effects remain under investigation. 'There’s no data suggesting graphene poses health hazards,' a spokeswoman notes, 'but research is ongoing.'
In the UK, Vector Homes is licensing PureGRAPH for use in plastic pellets for construction materials like fascia boards. Experiments show that graphene significantly reduces plastic’s flammability. 'It achieves the highest ratings in fire tests,' says Liam Britnell, co-founder and CTO of Vector Homes.
But here's where it gets controversial again: as wildfires become more frequent (https://www.metoffice.gov.uk/about-us/news-and-media/media-centre/weather-and-climate-news/2025/state-of-wildfire-report-2025), researchers like Eric Appel at Stanford University are developing gel-like fire retardants that can be sprayed on homes before a wildfire strikes. While promising, these solutions raise questions about their environmental impact and long-term effectiveness.
As we embrace these innovations, one question lingers: Are we sacrificing long-term sustainability for short-term safety? What do you think? Share your thoughts in the comments below—let’s spark a conversation about the future of fire-safe construction.
