Balloons in the night

Party balloons are mostly made of a natural latex tapped from rubber trees, and can be filled with air, helium, water, or any other suitable liquid or gas. The rubber's elasticity makes the volume adjustable.

Filling the balloon with air can be done with the mouth, a manual or electric inflater (such as a hand pump), or with a source of compressed gas.

When rubber or plastic balloons are filled with helium so that they float, they typically retain their buoyancy for only a day or so, sometimes longer. The enclosed helium atoms escape through small pores in the latex which are larger than the helium atoms. Balloons filled with air usually hold their size and shape much longer, sometimes for up to a week.