Fire-blocking chemicals promise safer buildings

"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, 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."

"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. "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."

A Belfast wood-treatment manager demonstrated a clear, salty flame-retardant liquid containing Burnblock and stated he had drunk it though he would not recommend doing so. Tests and a company video showed Burnblock-treated model houses resist fire: one untreated model collapsed, while the Burnblock-treated model charred in one corner but remained mostly unharmed. Company and maker declined to disclose full ingredients. Documentation from the Danish Technological Institute reportedly lists the active ingredient as "a natural component in the body" and mentions citric acid plus "a natural component in some berries". Experts note many 20th-century retardants are toxic and replacements have been underfunded.

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