New Fire Blocking Chemicals Offer Hope For Safer, More Sustainable Buildings

Inside a workshop in Belfast, a large vat filled with a clear liquid looks ordinary at first glance, but it holds something that could change how buildings are protected from fire. The liquid is a special flame retardant used for wood treatments, and its effectiveness has captured attention far beyond the workshop walls. Stephen McCann, general and technical manager at Halt, the company responsible for applying the treatment, jokes that the liquid is safe enough to drink. He claims to have tried it himself, although he quickly admits he would not recommend it because of its salty taste.

This liquid contains Burnblock, a flame retardant that has shown notable results in controlled fire tests. In a demonstration shared online, two small wooden model houses are exposed to a blow torch. The untreated model collapses under the flames, but the Burnblock treated house remains standing, damaged only by heavy charring in one corner. The striking contrast highlights why this treatment is attracting interest across the construction and safety industries.

A Mysterious Formula With Natural Components

Despite its growing reputation, the exact composition of Burnblock remains a closely guarded secret. Neither McCann nor Hroar Bay Smidt, the chief executive of the Danish company behind Burnblock, will reveal the full list of ingredients. However, documentation from the Danish Technological Institute offers some clues. It describes the flame retardant as containing a natural bodily component, along with citric acid and an ingredient found in certain berries. These elements appear to be combined to create a powerful protective treatment that is both effective and environmentally conscious.

Flame retardants have existed for centuries, used to slow the spread of fire and give people more time to escape. Many formulas developed in the 20th century, however, came with significant drawbacks. Some were highly toxic, raising health and environmental concerns that are still being addressed today. Chemist Alex Morgan from the University of Dayton Research Institute notes that the industry has struggled to create safer replacements. As regulations tighten and awareness grows, companies are now racing to develop more sustainable solutions.

How Burnblock Protects Wood From Fire

Burnblock works by changing how treated wood behaves when exposed to flames. When heat hits the surface, the material forms a thick layer of char, which acts as a barrier. This layer slows the spread of fire and protects the underlying structure. According to Bay Smidt, the treatment also releases small amounts of water that absorb heat and limit the fire’s ability to grow. By reducing oxygen flow to the flame, the treatment further suppresses burning and delays ignition.

One of the advantages of Burnblock is its versatility. It can be applied not only to wood but to other natural building materials as well, including dried seagrass. This flexibility offers architects and builders the chance to incorporate more sustainable materials into modern structures without sacrificing safety.

The Science Behind Deep Wood Treatment

At Halt’s facility, Burnblock is applied using a large machine known as an autoclave. It looks like two massive horizontal tubes stacked on top of one another. The upper tube holds the treatment liquid, while the lower tube is used for the wood itself. McCann explains that when wood is placed inside, the machine first removes the air with a vacuum. This opens the pores in the wood, making it more receptive to the treatment.

Once prepared, the wood is exposed to high pressure along with the flame retardant solution. The pressure varies depending on the species of wood, ensuring the treatment penetrates fully into the core. Afterward, the wood is transferred to a drying kiln. This critical step can take anywhere from ten days to six weeks. If the wood dries too quickly, it may crack or warp. If it dries too slowly, the structural integrity can be compromised. The process requires precision and constant monitoring.

Promise And Caution In The Future Of Flame Retardants

Experts such as Richard Hull, a professor emeritus at the University of Lancashire, see potential in treatments like Burnblock. Wood’s natural ability to absorb liquids allows its burning behaviour to be altered significantly, making it a promising material for fire resistant construction. Hull, however, remains cautious. He notes that the industry has seen many flame retardant innovations rise and fade. For example, clay nanocomposites received significant attention in the early 2000s but ultimately failed to make lasting impact.

Burnblock represents a new generation of flame retardant chemistry, one that aims to balance safety, sustainability and practical performance. Whether it becomes a long term solution remains to be seen, but its early success offers hope for safer buildings and cleaner materials in the years to come.