By bizn_fun 
I’m peering into a large vat containing a perfectly clear liquid – a special kind of flame retardant for wood products.
“You can drink it. I have,” says Stephen McCann, general & technical manager at Halt, a wood treatment company in Belfast. “I wouldn’t recommend it,” he adds, however. It’s very salty, apparently.
But this liquid, containing a substance called Burnblock, has been shown to prevent fire taking hold of wood in tests.
In a video the firm has shared online, external, two small model houses are blasted with a blow torch. One, treated with a different product, is engulfed in flames to such an extent that it collapses. The Burnblock-treated model gets heavily charred in one corner but remains otherwise unharmed.
What is Burnblock exactly? No-one will say. Neither Mr McCann nor Hroar Bay-Smidt, chief executive of Burnblock itself, a Danish firm, will confirm the ingredients. However, documentation on Burnblock’s website from the Danish Technological Institute states the flame retardant ingredient is “a natural component in the body” and that the mixture also contains citric acid and “a natural component in some berries”.
Flame retardants, chemicals added to products to try and slow down how they burn, have been around in various forms for centuries.
But many of the flame retardants developed in the 20th Century are highly toxic, external. “There hasn’t been a lot of investment in replacements so now all of a sudden people are scrambling to find them,” says Alex Morgan, a chemist and flame retardant expert at the University of Dayton Research Institute in the US.
When you try to set fire to wood treated with Burnblock, the material forms a protective layer of char, explains Mr Bay-Smidt. “It also releases some water,” he adds. “That helps absorb the heat and slows the fire’s spread.” And, it prevents oxygen feeding the flames. You can add Burnblock to other building materials, he says, including dried seagrass.