According to its developers, the fabric reportedly cools the air beneath it by up to 8° F.

Unlike traditional fabric used in the making of clothing that grows increasingly hot when the wearer is exposed to sunlight because the wearer’s body and clothing are both absorbing ultraviolet (UV) and near-infrared (near-IR) light from the sun, the new fabric reflects visible and near-infrared light, while also reflecting UV light.Source: Evan D. Patamia

To accomplish this, the team developed a mineral-polymer coating, which is comprised of both calcium carbonate and barium sulfate — both of which are natural minerals commonly found in chalk. Specifically, the calcium carbonate particles reflect visible and near-infrared light, while particles of the barium sulfate reflect UV light.

In the lab, the team coated small fabric squares with a polymer layer before dipping them repeatedly in solutions featuring calcium or barium ions, as well as carbonate or sulfate ions, which formed a chalky, matte finish on the fabric.

The team evaluated the cooling effectiveness of both treated and untreated fabrics during a day when temperatures exceeded 90° F, finding that the treated fabric exhibited a cooling effect of 8° F when compared to the ambient temperature during the mid-afternoon.

“The difference was even greater, a maximum of 15° F, between treated and untreated fabric, which heated the air underneath the sample,” the researchers noted.