Glow sticks are plastic cylinders that contain two liquids that temporarily create light when they are mixed together. The cylinders typically are about 4 to 5 inches (10 to 13 cm) long and less than 1 inch (2.54 cm) in diameter. Glow sticks are available in many colors and are often used for decoration or entertainment, such as at parties, concerts and other nighttime events. They also have some practical uses for camping, military or police operations, underwater activities or certain emergency situations. Thin glow sticks that are made of a more flexible plastic can take the form of necklaces, bracelets or other shapes.
Chemiluminescence
No matter what form they take, glow sticks depend on a chemical process known as chemiluminescence to produce their light. In chemiluminescence, a chemical reaction causes a release of energy. Electrons in the chemicals become excited and rise to a higher energy level. When the electrons drop back to their normal levels, they produce energy in the form of light.
Colors
The chemicals used to create this reaction in glow sticks usually are hydrogen peroxide and a mixture of phenyl oxalate ester and the fluorescent dye, or fluorophore, that gives the glow stick its color. Common colors of glow sticks include yellow, green, pink, blue and orange. They also are available in red, white, yellow-green and other shades and colors.
How it Works
A glow stick's hydrogen peroxide is contained in a small glass or breakable plastic vial that floats within the mixture inside the stick. This is why the glow stick's user must bend it to make it start glowing. When the stick bends, the vial breaks, the hydrogen peroxide is released, the chemical reaction begins, and the distinctive glow appears. The chemicals that are used might be somewhat toxic, so if the glow stick itself breaks, it should be thrown away, and the chemicals that might have leaked out should be washed off the user's skin and any other surfaces with which they came into contact.
Duration
In addition to the color, the duration of the glow — usually several hours — also depends on the exact composition and quality of the chemicals inside. Some people say that a glow stick can be preserved by sticking it in a freezer. Indeed, cooling a glow stick will slow down the chemical reaction that is taking place inside it. The glow won't be as bright, but it will continue for a longer period of time.
Conversely, heating a glow stick, such as by placing it in a microwave, will speed up the chemical reaction. This will produce a brighter light. The glow won't last nearly as long, however, because the reaction will use up all of the available hydrogen peroxide more quickly. Microwaving glow sticks might not be recommended by some manufacturers, and caution should always be used when it is being done.