Stop the Pop!

1. Take one inflated balloon.

2. Take one sharp needle.

3. Stick needle into balloon.

Do you expect to hear a loud POP???

Most of the time, yes. But as the photo at right shows, it is possible to stick a needle into a blown-up balloon without popping it. The secret lies in knowing where and how to insert the needle.

First of all, only fill the balloon about half-way with air. Select a spot at the top or bottom of the balloon where the rubber isn't stretched out as much as it is in the middle. Push the needle in slowly, while twisting it a little. The rubber will resist at first, then give way. You may need to try a few times, but eventually you will be able to do this. Make sure that you have a sharp needle, and grease it with some vegetable oil if you are having trouble.

How is this possible? Rubber is composed of long, stringy molecules (picture a bowl of wriggly worms - yuck!). By pushing the needle in slowly, you allow the molecules to wriggle away from the point. If you insert the needle too quickly, they don't have time to get out of the way, and the balloon will pop. In the middle of the balloon, where the rubber is stretched thin, the molecules are also stretched out, and they can't move as easily. While it is possible to insert a needle into a balloon in the middle parts, it is much harder.