Bev recently received a black light from a fellow sea glass fanatic and has been going through all of her sea glass to find the UV glass pieces. You can't imagine her excitement when she found several pieces. It was a treasure hunt in her sea glass studio!
As you can see, the photo on the left is a pile of light green sea glass. On the left is the same pile under the blacklight. How does this happen?
According to Google:
Both green Depression glass and Vaseline glass will glow under a black light due to the uranium oxide content in the glass. Old Burmese glass fluoresces a similar yellow-green color. American colorless pressed glass made before 1930 is said to fluoresce yellow, while reproductions generally do not.
Uranium oxide? Isn't uranium dangerous?
Here's an article from Beach Combing Magazine written by Kirsti Scott. She explains:
Uranium glass is the most common ingredient in UV glass. There are several types of glass that were made with uranium in them. Yes, the same uranium used for bombs and nuclear power reactors. Fortunately, the amounts used to make uranium glass are tiny.
Vaseline glass, or Canary Glass, is a yellow-green glass mainly produced for tableware and household items from around 1840 up until World War II. It gets its yellow or greenish-yellow color from uranium dioxide (UO2), which was used as a colorant. Vaseline glass came as glasses, plates, lamps, doorknobs, bottles, decorative items, decanters, and more. The uranium in Vaseline glass gives it the glass its bright-green color in natural light, and causes the glass to glow vivid neon green under a black light.
Other types of uranium glass, which also glow under UV light, include opalescent green uranium glass, teal carnival glass, milk glass, opaque custard and Burmese glass, opaque or semi-opaque jadeite glass, and transparent or semi-transparent pale-green Depression glass. Uranium glass was also used in marbles to create swirls of bright colors, so your sea marbles may glow under a black light, too.
During WWII, the U.S. confiscated all uranium, and prohibited the use of uranium for glass production. After the war, production resumed, though a lower-grade, less-fluorescent version of uranium was used and only limited quantities are produced today, mostly for novelty or decorative pieces. No more place settings of uranium glass produced these days.
A property of uranium—totally unrelated to its fluorescence—is its radioactivity. The radioactivity of uranium glass is actually measurable with a Geiger counter. However, since only small amounts of uranium, often less than 1%, were used during the manufacture of the glass, the amount of radioactivity in uranium glass is not considered harmful. And, the radioactivity doesn’t leak out quickly into liquids stored in a uranium glass container, so it’s safe to use.
Maybe if you ground the glass into powder and swallowed the results it might be unhealthy, but the most dangerous part of dealing with uranium glass is actually using the black light, which emits ultraviolet rays. (Safety note: Never look directly into a UV flashlight, don’t shine it into anyone else’s eyes, and if you’re particularly worried about UV exposure, wear UV protective glasses.)
So there you have it. The uranium in the glass won't hurt you but the black light could. Stay safe people.
BeLo The Sea Treasures
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