Experiment with Things that Glow under a Black Light

As the title suggests, here is my list of things that glow under a black light. After you've read it, you can keep reading for an explanation of black lights and my program, or you could move on. Either way, thanks for reading:)

Things that Glow Under a Black Light:

Tonic water
Laundry detergent
Area around the dark spots of a banana
Highlighter ink
Security strip on a recent US $20
Irish Springs soap
Petroleum jelly
Canola or vegetable oil
White paper
White LEGO pieces
Glow in the dark paint
Glow sticks (alright the last two already glow in the dark, but they glow even brighter under a black light)
Tooth whitening products
and believe it or not, Monster energy drinks

Every month I get the chance to do science experiments at a local private school. Typically my library program happens before I go to the school, which gives me a chance to see what experiments will work well in a classroom setting. But this time, I got an idea for my library program from the school program.

Glow in the Dark Experiments was my topic last month, and while I was there, one of the students mentioned that they had been using black lights to identify certain minerals in rocks. He thought it would be cool for us to experiment with other things that glow under black lights. I agreed =D

I'm sure everyone is familiar with black lights, but I wasn't quite sure how they worked. Black lights are emitting two kinds of light; light we can see, and light we can't see. The light we can see is the purplish color, and the light we can't see is called ultraviolet light. This ultraviolet light (UVA) is the harmless cousin to the harmful ultraviolet light (UVB) that gives you a sunburn.

If something glows under a black light, it is because it contains phosphors. Phosphors are a substance that emit visible light when exposed to radiation. So they are absorbing the ultraviolet light from the black light, and converting it to visible light.

Turns out there are quite a few things that glow under a black light, and I figured I'd list them for you here. My time at the private school was mostly spent seeing what would glow and what wouldn't. If you want to do this program, I would suggest grabbing a mixture of things that glow and things that don't, and see what you see. Also be willing to test things that are around the room...

Glow in the Dark Experiments

Who doesn't like stuff that glows, and I figured it was appropriate for Halloween :)

Glow Sticks

An easy way to get glowing is glow sticks. Basically it is a chemical reaction between two compounds that, when mixed, release excess energy as light. If you are interested, it is a process called chemiluminescence.I found that the kids understood the idea of a chemical reaction if you talk about mixing baking soda and vinegar, as most have done that.

Once we understood a little more about chemical reactions, I actually cut open one of the glow sticks. Each glow stick is actually made of two sticks; one plastic one that you feel, and one glass one that is lodged inside. When you crack a glow stick you are actually breaking the inner glass tube that releases one chemical into the other and presto, instant light!

Glow Paint

Let your participants paint a design on a black piece of paper without telling them that it is glow in the dark paint. Once they are finished, turn off the lights and watch their surprise. Once they've seen the affect, you can talk about the science behind it called photoluminescence (the paint absorbs photons and then releases them in the dark is the short answer hehe. Another way of thinking about it is the paint getting excited and then releasing this excitement as light, just like we might release our excitement by dancing).

Finally, we mixed some GAK with glow paint (but glow powder would work just as well). This experiment is fun to do no matter what, and seeing it glow in the dark after you mix it just makes it that much cooler =D