It Glows! But How?

Excited child drags mom by the hand into a bathroom. The bathroom door slams shut and child reaches up to turn off the bathroom lights.




“It glows in the dark! It glows!” We’ve all experienced this scene, both as a child and then again as a parent. Puzzles, shirts, shoes, pens, fingernail polish, lipstick, face paint, no matter what it is, we all are fascinated by things that glow.

Why do some things “glow”?

Let’s start with science: fluorescence v. phosphorescence. Both words are mouthfuls. Essentially, fluorescence refers to things that glow when energy (like UV light) is put on them. Fluorescent items do not glow when light is not shining on them. Phosphorescence, however, refers to items that continue to glow even after the energy source is removed, like glow-in-the-dark toys.

So which type is the zinc sulfide powder we sent you? It is a phosphorescent! If you give it enough light, it will continue to glow.

How? Glad you asked. In simple terms, when light is shining on the powder (or any other phosphorescent item), the electrons in the item’s atoms become so excited and energized that they actually give off light themselves and will continue to give off light until they’ve settle back into their normal state. Pretty cool, huh?


This website has several fun ideas about making things glow. Some of our favorites include glow-in-the-dark pumpkins, bouncy balls, and water beads. Can you think of other ways to use your zinc sulfide?


Questions? Email us at, visit, and read our FAQs page.