Have you heard of a Prince Rupert’s Drop? No, it’s not the latest dance craze, nor is it the next evolution of an infamous piercing.
Drop a blob of molten glass into a bucket of cold water and it forms into the shape of a tadpole as it cools. This formation is called a Prince Rupert’s Drop or ‘Dutch tear.'
If you hit a Prince Rupert’s Drop as hard as you can, it will not break. In fact, even if the strongest man in the world had a good bash at it, this glass shape will remain intact. However, chip even the smallest part of the tail off and the whole thing will shatter into tiny pieces.
This is because the bucket of cold water cools the surface of the drop so quickly that the inside is still molten when the outside is solid. When the inside begins to cool, it pulls in and contracts the outside surrounding it, which strengthens the whole structure. Well, all except for the tail, which is too thin to have layers and becomes the structure’s weakest point.
The sudden explosion of glass happens so quickly that the only way to capture it for human eyes to see is to play it in slow motion at 130,000 frames per second. That's exactly what this video below from the YouTube channel SmarterEveryDay shows.
For the past 400 years, scientists and researchers have used Prince Rupert’s Drops to observe material failure and elasticity. The earliest record of ‘glass bubbles’ dates to 1660, where they were presented to the Royal Society of London.