Modern bulletproof glass still relies on lamination. Also known as ballistic glass, the tough transparent armor, which fortifies vehicles used for transporting the pope, the U.S. president, and other dignitaries, often contains several layers of annealed glass bonded together with a film of poly(vinyl butyral), polyurethane, or other polymers. It can also be made from multiple bonded layers of glass and polycarbonate measuring up to several centimeters in thickness. Ballistic glass is strong, tough, and durable but much too heavy, thick, and expensive for mobile touch screens and ordinary automobile windshields. That’s where thin, chemically strengthened glass comes in.