Looking for the Glow: Which objects glow under black light?

(From Experiment Central, published by U·X·L and available in Science Resource Center, a Gale online database.)

Fluorescence is a scientific term that refers to something (usually a chemical compound) that reacts with light energy and glows brightly. In this project, you will examine compounds that react with ultraviolet light (UV), causing the compound to glow. When certain chemicals are exposed to UV light, the molecules absorb the light energy and then release it in the form of visible light.

Level of Difficulty

Easy/moderate

Materials Needed

• UV light, also called a "black light" (fluorescent fixture with black or dark purple lightbulb)
• Wisk or Woolite brand laundry detergent
• glow-in-the-dark plastic (can be a plastic toy)
• calcite (mineral found in nature or rock stores)
• white paper
• objects to test (rocks and minerals, household detergents or cleaners, clothing, plants, etc.)

Approximate Budget

• $20 for black light, $5 for detergents and for calcite.

Timetable

15 Minutes.

How to Experiment Safely

The chemicals in many detergents can irritate the skin, so avoid contact with the skin and eyes. Always use caution when handling household chemicals. Normally UV light is considered dangerous and harmful to the eyes. However, the fixture you are using emits very long wavelength UV, which is safe to use.

Step-by-Step Instructions

1. Place the black light in a dark room and turn it on.
2. Place a small amount of Wisk or Woolite on a piece of white paper. Let the detergent dry a little and place the paper so that the light shines on it. Notice the color of the chemical. Wisk is blue/green. Woolite is green/yellow.
3. Place different objects in front of the black light, such as white socks, white or colored towels, or blue jeans. Record any color you notice. Test groups of objects such as rocks, minerals, household detergents, flowers, fabric dyes, and plastic objects.
4. Repeat the test for each object. Record your observations.