Now, glass paint to keep metal roofs cool on sunny days

Boston: Scientists have developed a new, environment-friendly and inexpensive paint out of glass that bounces sunlight off metal surfaces - keeping them cool and durable. "Most paints you use on your car or house are based on polymers, which degrade in the ultraviolet light rays of the sun," said Jason J Benkoski at the Johns Hopkins University Applied Physics Lab.

Glass, which is made out of silica, would be an ideal coating. It's hard, durable and has the right optical properties. But it's very brittle. To address that aspect in a new coating, Benkoski started with silica, one of the most abundant materials in the Earth's crust. He modified one version of it, potassium silicate that normally dissolves in water.

His tweaks transformed the compound so that when it's sprayed onto a surface and dries, it becomes water resistant. The paint Benkoski's lab is developing is intended for use on naval ships. But it has many other potential commercial applications. "You might want to paint something like this on your roof to keep heat out and lower your air conditioning bill in the summer," he said. It could even go on metal playground slides or bleachers.