How Glow in the Dark Lights Work

glow in the dark lights

Many of us have a few glow in the dark toys or stickers that we love to take out and shine in the darkness. These items (as well as natural things like fireflies and comb jellies) glow in the dark because of something called bioluminescence. Bioluminescence occurs when an animal contains a chemical that causes it to light up. In some cases, animals glow because it helps them protect themselves from predators or to camouflage in the water. Other animals glow as a way to attract mates or to communicate with other members of their species.

Glow in the dark items and toys glow because of a process called phosphorescence. Phosphorescent materials are able to store energy in the form of visible light and then slowly release it when the source of light is removed. This is similar to how fluorescent materials work, but phosphorescent products don’t require any special chemicals and last much longer than fluorescent items. Glow in the dark items usually need to be charged before they will light up, and the time it takes for them to reach peak brightness varies from product to product.

In the past, most glow in the dark items were made from a compound called zinc sulfide. Zinc sulfide absorbed light and then slowly released it over time. When additional chemicals called phosphors were added to the zinc sulfide, it turned out to be much brighter and lasted much longer. Modern glow in the dark paints and plastic stars use a different phosphor, strontium aluminate, which is more durable and safer than zinc sulfide. Some paints also contain the rare earth element europium to enhance their luminosity.

To charge a glow in the dark object, place it under a regular light bulb or black light for a few minutes. Black lights emit a large amount of ultraviolet (UV) radiation, which is able to penetrate and charge the phosphors in a glow in the dark item. Regular light bulbs also emit UV radiation, but not as much as black lights. Some older glow in the dark items used radioactive elements for continuous luminosity, but these are no longer available as they are very toxic.

When a glow in the dark item is charged, it will glow for about 30 minutes at its peak intensity before it starts to fade. Several factors affect how bright the glow appears, including how adapted you are to the dark and the ambient light in the room.

While you can purchase glow in the dark products at most stores, it’s best to purchase them online. This is because online retailers are able to sell items for a lower price, and most of them have been thoroughly tested for safety. Additionally, online retailers will often include tips and information about how to get the most out of your purchase. For example, they may suggest that you store your glow in the dark items in a cool dry place to prolong their lifespan.