Engineers in Australia have developed a novel, water-based spray capable of making everyday cotton clothing and textiles significantly more fire-resistant. The non-toxic formula, created by a team at the University of New South Wales (UNSW), applies a virtually invisible protective coating that slows ignition and drastically reduces heat transfer, a breakthrough that could offer a crucial layer of protection for households in bushfire-prone regions and for individuals in emergency situations.
The new spray addresses a persistent challenge in textile treatments: adding fire retardancy without compromising the fabric’s natural feel and performance. Unlike previous methods that can leave materials stiff or unable to breathe, the UNSW solution leaves cotton soft and breathable, with no discernible smell or change in texture. This allows for the treatment of common household items such as shirts, pants, and bedding, transforming them into temporary barriers against intense heat and flame without altering their comfort or appearance.
A New Protective Chemistry
The effectiveness of the spray lies in its carefully selected, non-toxic ingredients. The research team, led by Professor Guan Yeoh from UNSW’s School of Mechanical and Manufacturing Engineering, formulated the solution using a combination of phosphorus and nitrogen-based compounds, which act as binders, and a plant-derived cellulose extract. This extract is commonly sourced from renewable biomass like wood pulp or cotton itself. When sprayed onto a fabric, these elements self-assemble into a thin, stable, and protective coating that bonds strongly with the natural cotton fibers.
The mechanism activates under heat. When exposed to a flame or high temperatures, the coating undergoes a chemical reaction that forms a stable, insulating layer of carbon char on the fabric’s surface. The phosphorus in the formula is crucial for this process, as it strengthens the carbon layer, making it more effective at repelling heat and preventing the underlying fibers from catching fire. This char layer acts as a physical barrier, slowing the transfer of heat to the material and the skin beneath it. The final product uses a low concentration of about 10 to 15%, which makes it easy to apply and allows it to dry almost instantly.
Performance Under Pressure
The UNSW team conducted extensive laboratory testing to quantify the spray’s protective capabilities, yielding impressive results. Treated cotton samples were exposed to direct flames and compared against untreated samples, demonstrating a marked improvement in fire resistance across several key metrics.
Delayed Ignition and Heat Reduction
In lab trials, the coated fabric took twice as long to ignite as its untreated counterpart. Once alight, the flame’s intensity was significantly suppressed. The treated material released nearly 50% less heat, and instead of bursting into flames, its surface only charred. Perhaps most significantly, the peak heat release rate (PHRR)—a measure of a fire’s maximum intensity—was reduced by approximately 89%. This means the treated cotton produced only a fraction of the heat output of untreated cotton, a critical factor in reducing fire spread and the severity of potential burns.
Protecting the Wearer
The spray also proved highly effective at preventing heat from reaching the skin. In simulated fire environments, researchers found that the coating could reduce the temperature on the textile’s surface by 30 to 40%. Even when the external temperature reached 100 degrees Celsius, the treated fabric maintained a skin-side temperature below 40 degrees Celsius. This difference is substantial enough to prevent or dramatically reduce the severity of scalding and burn injuries.
Designed for Practical Use
A primary goal of the two-year project was to create a solution that was not only effective but also practical for widespread consumer use. The researchers successfully developed a formula that is odorless and does not stiffen the fabric, ensuring treated clothing remains comfortable to wear. According to Professor Yeoh, the item of clothing feels the same after treatment as it did before.
The fire-resistant effect is designed to be temporary. While the coating can withstand light water contact, it dissolves completely during a rigorous machine wash. This feature was intentional, demonstrating that the treatment provides reliable protection until it is washed off, at which point the fabric returns to its original flammability. This allows users to apply the protection when needed, such as during high-risk fire seasons, and remove it later. The product also has a long shelf life; if the bottle is kept sealed to prevent oxidation, it is expected to last for more than a year.
Development and Broader Context
The research was funded through a $5 million grant from the Australian government’s ARC Research Hub for Fire Resilience Infrastructure, Assets and Safety Advancements (FRIASA). Professor Yeoh’s team has a track record in developing commercial fire-safety products. In 2023, they created FSA Firecoat, the first fire-retardant paint in Australia to pass the demanding BAL-40 bushfire resistance test, which is now sold commercially. The team focused on cotton for this project because it is one of the most widely used materials in the global textile and clothing industry. The successful development of the spray provides a new tool for enhancing personal safety, especially as climate change increases the frequency and intensity of wildfires.
