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Bryan Gardiner on some of the science behind Gorilla Glass:

The interplay between compression and tension is best demonstrated by something called a Prince Rupert’s drop. Formed by dripping globs of molten glass into ice water, the quickly cooled and compressed heads of these tadpole-shaped droplets can withstand massive amounts of punishment, including repeated hammer blows. The thin glass at the end of the tail is more vulnerable, however, and if you break it the fracture will propagate through the drop at 2,000 miles per hour, releasing the inner tension. Violently. In some cases, a Prince Rupert’s drop can explode with such force that it will actually emit a flash of light.

The entire article is a fascinating story of how Corning’s now-ubiquitous material came to be. After the glass was sitting around for years, unused, Steve Jobs came calling…

And a hint at the future:

This remarkably thin, rollable material is called Willow. Unlike Gorilla Glass, which is meant to be used as armor, Willow is more like a raincoat. It’s durable and light, and it has a lot of potential. Corning imagines it will facilitate flexible smartphone designs and uber-thin, roll-up OLED displays. An energy company could also use Willow for flexible solar cells. Corning even envisions ebooks with glass pages.

Eventually, Willow will ship out on huge spools, like movie reels, each holding up to 500 feet of glass. That is, once someone places an order. For now, rolls of glass sit on the Harrodsburg factory floor, a solution waiting for the right problem to arise.