Researchers at the University of Massachusetts Amherst have created a unique fabric coating that can cool the air underneath it by up to 8°F. This eco-friendly innovation could change how people stay cool outdoors as global temperatures continue to rise. This was presented at the 2024 American Chemical Society Fall Meeting and could soon change how we deal with heat.
The breakthrough uses natural minerals—calcium carbonate and barium sulfate—that are found in chalk. These minerals work by reflecting sunlight and stopping heat from being absorbed into fabrics. Unlike other high-tech cooling textiles that rely on complex synthetic materials or harmful chemicals, this new approach is simple, sustainable, and environmentally friendly.
Trisha L. Andrew, a chemist and materials scientist who led the research, explained the science behind it. “If you walk out into the sunlight, you will get increasingly hot because your body and clothing are absorbing ultraviolet (UV) and near-infrared (near-IR) light from the Sun,” Andrew said. “And as long as you’re alive, your body is generating heat, which can be thought of as light, too.”
The team used a process called chemical vapor deposition, or CVD, to apply the coating. They first covered small fabric squares with a thin polymer layer and then dipped them multiple times in solutions containing calcium or barium ions and carbonate or sulfate ions. This created a chalky, matte finish on the surface of the fabrics.
This coating makes the fabrics capable of reflecting different types of light from the sun. Calcium carbonate is excellent at reflecting visible and near-infrared light, while barium sulfate is highly effective at blocking ultraviolet rays. Together, they prevent the fabric from heating up under sunlight, creating a cooling effect for the person beneath it.
“What makes our technique unique is that we can do this on nearly any commercially available fabric and turn it into something that can keep people cool,” Andrew said.
To see how well their invention worked, the researchers tested both treated and untreated fabrics outdoors on a sunny day. Temperatures were over 90 degrees Fahrenheit (about 32°C). The coated fabric showed a cooling effect of up to 8°F compared to the surrounding air.
“The difference was even greater—up to 15°F—when comparing the treated fabric to untreated samples, which heated the air underneath them,” Andrew noted. Evan D. Patamia, a graduate student involved in the project, described his experience standing under the fabric. “What is underneath the sample feels colder than standing in the shade,” he said.
These results showed that the coated fabric can make outdoor environments much more comfortable. It could be especially useful in regions with extreme heat or where air conditioning is not widely available.
The fabric coating is not only effective but also practical. It survived washing and drying without losing its cooling properties, which makes it suitable for everyday use in clothing and outdoor gear. “Our method doesn’t just work in the lab. It holds up in real-world conditions,” Andrew explained.
“We’re able to reduce how hot a person feels without any power input. This could be a valuable resource where people are struggling to stay cool in extremely hot environments,” Patamia added.
The invention came at a time when extreme heat is becoming one of the biggest challenges due to climate change. Existing cooling fabrics often use energy-intensive production methods or synthetic materials like titanium dioxide and aluminum oxide, which are not sustainable for mass production.
By using common and environmentally friendly minerals, this chalk-based coating provides a safe solution. It has the potential to be applied to tents, awnings, sportswear, and even large outdoor coverings to keep people cool.
“If successful, this could be a game changer for communities facing extreme heat,” Andrew said with optimism.
