These People Love to Collect Radioactive Glass. Are They Nuts?

Some glassware collectors take a handheld black light along with them when they shop in order to test Vaseline glass, also known as canary glass or uranium glass. Real uranium glass will glow green under a black light. Glassmakers began using uranium as a coloring agent in the late 1700s, but it wasn’t until the 20th century that we knew how dangerous radioactivity is. Still, Vaseline glass continued to be made, with the exception of the World War II years, up to the present day. That’s because the tiny amounts of radiation emitting from Vaseline glass are smaller than radiation emitted from many other things we encounter in our everyday lives. So why does it glow?

Even if radioactivity is the thing that makes Vaseline glass cool, it’s not what makes Vaseline glass glow, says Barrie Skelcher, who’s written two Vaseline glass books of his own. That may come as a surprise to many Vaseline glass collectors, who assume that radioactivity is the reason why Vaseline glass glows under ultraviolet light, confusing the cartoon depiction of radioactivity for the science.

“It’s the chemistry of uranium that makes Vaseline glass glow, not radioactivity,” Skelcher says by phone from England, where he lives with his wife, Shirley, and 500 or so pieces of Vaseline glass in a collection that once numbered more than 1,000. “It wouldn’t make any difference whether the glass contained depleted uranium with the 235 isotope removed or natural uranium; the chemistry is identical. Uranium fluoresces under UV light.”

In other words, glass containing uranium will glow under UV light even after all the radiation has, er, radiated. The danger associated with uranium glass pales in comparison with glass that contain lead, arsenic, cobalt, or a number of other colorants and additives. And you’ll receive more dangerous radiation from the black light than from the glass. Still, the story of Vaseline glass is fascinating. I was surprised to learn that the name “Vaseline” was given to uranium glass because that’s the color Vaseline used to be! (Eww.) You can read plenty more about Vaseline glass at Collectors Weekly.

(Image credit: Dave Peterson at Vaseline Glass Collectors, Inc.)

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'People love to smoke. Are they nuts?'

People do things that shorten their lives (as well as the people around them) all the time. Accept that.
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'After all the radiation has, er, radiated', the glass will no longer contain any uranium - it will have decayed into lighter elements. The glass might possibly still glow under UV for other reasons, but not because it contains uranium. Of course, it would take an insanely long time for all the radiation to die down. Natural uranium is mostly 238, which has a half-life of 4.5 billion years, and its decay products (and their decay products, etc.) are also radioactive and would take additional time to decay.
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I had only recently heard about such glasses, and instead had been keeping an eye out in antique stores for orange Fiestaware which used to use uranium oxide until the whole line was discontinued for lack of sales in the 70s. They make for a handy demonstration of radioactivity, although just about anything ceramic will have some amount of radioactivity and it just depends on how good your detector is, etc. On that note, these things can peg the meter on a Geiger counter, but it is misleading because Geiger counters, especially cheap ones, are often calibrated for higher energy radiation and are much more sensitive to lower energy radiation. So if you have equal numbers of high and low energy particles being emitted, the latter shows as larger signal on a Geiger counter, even though the former can cause a higher dose.

And the article was a bit loose about radiation. I wouldn't go as far as to say x-rays are worse than beta particles, as it really comes down to how much, in what situation, and at what energies. Low energy x-rays can be stopped by a lot less than lead, for example.
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