By Peter.
Peering into a massive vat of crystal-clear liquid at a wood treatment facility in Belfast, it’s hard to imagine this unassuming solution could defy flames. “You can drink it. I have,” quips Stephen McCann, general and technical manager at Halt, a Belfast-based wood treatment company. “I wouldn’t recommend it,” he quickly adds—it’s apparently very salty. This non-toxic concoction, featuring the innovative substance Burnblock, has proven in rigorous tests to shield wood from catching fire, offering a game-changing alternative to hazardous legacy chemicals.
In a compelling demonstration video shared by Halt, two miniature model houses face a blowtorch assault. The one treated with a conventional product erupts in flames, collapsing into ash. Its Burnblock counterpart? Just a charred corner, standing resilient otherwise. It’s a stark visual of how this Danish-developed retardant is reshaping fire safety for construction and beyond.
What Exactly Is Burnblock? A Patented Blend of Natural Secrets
Burnblock, from the Danish company of the same name, remains shrouded in proprietary mystery—neither McCann nor CEO Hroar Bay-Smidt will spill the full recipe. However, certification documents from the Danish Technological Institute reveal key clues: The core flame-retardant agent is a natural component found in the human body (widely understood as phosphates, essential for energy transfer in cells), blended with citric acid and a natural component in some berries (likely an antioxidant like quercetin from sources such as cranberries or blueberries).
Patents further detail a water-soluble formula dominated by diammonium phosphate (DAP) and monoammonium phosphate (MAP)—common fertilizers derived from natural minerals—in ratios like 75% DAP to 25% MAP, creating a latent hardener that bonds seamlessly with wood fibers. This eco-friendly mix is 100% biodegradable, free of halogens or heavy metals, and meets stringent standards like EN 13501-1 (Euroclass B fire rating) and EN 45545 (railway safety). No wonder it’s Cradle to Cradle Certified—leaving no residues, stains, or health risks.
How Burnblock Works: Char, Cool, and Choke the Flames
When heat hits, Burnblock triggers a three-pronged defense:
- Char Formation: The treated wood carbonizes into a thick, insulating barrier that shields unburned material beneath.
- Water Release: Bound moisture evaporates, absorbing intense heat like a built-in sprinkler.
- Oxygen Blockade: Phosphates bind with flames, starving the fire of fuel and halting spread.
This intumescent action—expanding to swell and seal—makes it versatile for wood, plywood, particleboard (like MDF/OSB), cellulose insulation, and even natural fibers like dried seagrass. Unlike toxic 20th-century retardants (e.g., halogenated compounds linked to endocrine disruption and environmental persistence), Burnblock invests in safety without compromise.
As chemist Alex Morgan from the University of Dayton Research Institute notes, “There hasn’t been a lot of investment in replacements, so now all of a sudden people are scrambling to find them.” Burnblock arrived just in time.
Real-World Impact: From HS2 Tunnels to Everyday Builds
Halt, operational in Belfast for nearly four years, has integrated Burnblock into hundreds of UK and Irish projects—restaurants, hotels, offices, and high-profile infrastructure like HS2 (the UK’s mega-rail link). For HS2, treated wooden hoardings line tunnel construction sites, buying precious evacuation time in fire scenarios. “It could be quite difficult to get out of the tunnel, so they need as much time as possible,” McCann explains.
To date, no Halt-treated structures have suffered fire damage—a perfect record underscoring Burnblock’s reliability.
Why Now? A Greener Path to Fire Safety
Flame retardants date back centuries (think alum in ancient fabrics), but modern synthetics often carry hidden dangers. Burnblock flips the script: Non-toxic, naturally derived, and applicator-friendly (as powder or liquid), it’s poised for broader adoption in sustainable building. As regulations tighten on harmful chemicals, innovations like this aren’t just safer—they’re essential for a fire-resilient future.
Curious? Check out Burnblock’s demos or Halt’s applications. In a world racing toward net-zero, this salty secret might just be the spark we need.
