We’ve all been there: You put your hand on a metal surface like a bench, slide or even a smartphone on a brilliantly sunny day, only to find that it's too hot to touch. An intriguing piece of research, though, has found a way to stop metal from heating up like this in sunlight.

A team from the John Hopkins University Applied Physics Laboratory (JHUAPL) developed a glass-based paint that reflects all sunlight, keeping metallic surfaces relatively cool. Glass, made out of silica, is very brittle by itself, so researcher Jason Benkoski from JHUAPL and his team created an inorganic version of potassium silicate that dries when it is sprayed on a surface. The research was presented on Sunday, August 16, at a meeting of the American Chemical Society (ACS) in Boston.

To create the reflective spray, plasticizers, gelling agents and water-insoluble substances were added to the silicate. This created a thick, water-resistant foam coating that not only sticks to metals such as aluminum, but also reflects sunlight. The inorganic compound is apparently stable enough to remain effective for hundreds of years, according to Benkoski. It can also expand and contract without cracking. What’s more, the materials needed to make it are not only abundant, but inexpensive too.

Any surface coated with the paint will remain at air temperature, or even slightly cooler, as the paint doesn’t absorb any of the Sun's rays. This means that things like benches and slides could be coated in the spray and kept at a safe temperature. In addition, once the spray is applied, it cannot be removed; it will not even dissolve in water, so it is impervious to rain.

^{The video above explains how the paint was made, and how it works. ACS/JHUAPL.}

“Most paints you use on your car or house are based on polymers, which degrade in the ultraviolet light rays of the Sun,” Benkoski said in a statement. “So over time you'll have chalking and yellowing. Polymers also tend to give off volatile organic compounds, which can harm the environment. That's why I wanted to move away from traditional polymer coatings to inorganic glass ones.”

The team was part-funded by the US Office of Naval Research to develop the paint for use on ships, but it has many other applications including benches and even roofs. “You might want to paint something like this on your roof to keep heat out and lower your air conditioning bill in the summer,” added Benkoski.

The team hopes to start field testing the paint in about two years.