The Prince Rupert’s Drop Glass Structure Is Strong Enough to Shatter a Bullet

If you’re like me, you probably don’t think about glass being particularly strong. It’s pretty, and I guess they can make it bulletproof if you’re the president or the pope, but glass that could actually shatter a bullet?

Color me intrigued.

It’s called Prince Rupert’s Drop, and no, it’s not some kind of setup for a prank phone call. Or a s*x joke. Probably.

Here’s a video of one shattering a bullet at 150,000 frames per second.

To make one, a glass handler lets molten glass drop into a vat of water, resulting in a piece of glass that looks like a tadpole with a long, ropey tail. The “drop” part – Prince Rupert’s Drop – is one of the strongest things in the world.

The sad part of the story is that, even though the bulbous end of the drop literally breaks bullets, the other end is its Achilles heel – if it snaps, the entire thing vaporizes before you can breathe.

Adam Savage and Jamie Hyneman discussed the magical drop on an episode of Mythbusters in 2014. On the program, they explain that the rapidly cooling surface of the glass and the still-molten interior combine to form an indestructible outside and an inside taught with residual stress.

As the entire drop retracts as much as possible as it cools, the shape and the tension form a stunning shock absorber.

In Savage’s words, it’s the “power of compressive strength!”

When you cut the tail, all of the compression and tension are released at once, causing it to explode like a deadly bomb – but one that’s harmless, since the glass vaporizes instead of exploding outward.

Everything the rapidly cooled exterior has been holding together just goes up all at once.

I know you’re going to watch these videos more than once – I did.

Isn’t science amazing?