WAY TO GLOW!

Summer is now almost fully upon us here along the north shore, so it's time to put new batteries in my Stink-Finder. I think I mentioned this handy gadget in a post last summer, but I’ll quickly recap here. A Stink-Finder is a palm-sized black light that can be used to locate invisible pet stains on the carpet, which glow, or fluoresce, under the UV light. Well, I don’t have that problem with my pets, thank goodness. So what do I need with a black light? I use it for identifying a certain kind of beachglass called “Vaseline” glass. This beachglass, which dates usually to the 1920s, has a small amount of uranium dioxide (about 2%) and this tiny bit of radiation (about as much as the background radiation of the Universe that we live in everyday) makes it glow under a black light. It’s not dangerous to handle, and lots of fun to find. Lying on the sand in the sunlight, Vaseline glass looks pretty much like any other piece of pale greenish-yellow (hence the name) glass, but take it home and go in your bathroom with a Stink-Finder—I just meant because it’s dark in there—and watch the Vaseline glass glow bright green, and sometimes even orange. So, now with my new batteries, I’m ready to go. But while I was there in the bathroom in the dark, I ran the black light over the wall where I’d painted a mural when I first moved in. And a light went on in my head.

The mural I painted is a pond scene at twilight. It has frogs singing in the reeds, a cricket band on shore, and moths and fireflies going up the wall. For the fireflies, I used phosphorescent paint. They, too, glow in the dark—but only if I turn on the incandescent light for a few moments first. I wondered about the black light, so I held the S-F up to a firefly, and sure enough, the fireflies glowed, too, without the help of the incandescent bulbs. This got me thinking about day-glo paint and my old Jefferson Airplane black-light poster from the ‘60s and something I’d seen on TV about scorpions, the dial on my watch when I press that little knob—and I decided I better check it out. Some of you may already know this, but I was surprised to learn that florescence and phosphorescence, which I have been using pretty much interchangeably all my life, are not exactly the same thing. Without going into all the technical and scientific jargon, I learned that fluorescence means something glows under a black light, and stops glowing, like Vaseline beachglass does, when the black light is removed. Phosphorescence means something can store up energy and glow for a while without a black light present, like my painted fireflies.




A third kind of light, bioluminescence, is light created by a chemical reaction in living creatures, including real, not painted, fireflies.









Photos, top to bottom:

1) Vaseline beachglass fluorescing under the Stink-Finder
2) phosphorescent-painted firefly in my bathroom under the S-F
3) a scorpion, which naturally fluoresces under a black-light
4) bioluminescent jellyfish