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There are sellers on eBay who call any piece of glass that’s yellow, light green, or greenish-yellow “vaseline.” While vaseline glass IS that color, that’s like saying all red fruits are apples.
In the photo below, the collie on the right is Vaseline. The collie on the left is Golden Opaline – sometimes mistakenly identified as Vaseline or “Vaseline Opalescent”.
What is Vaseline Glass?
Vaseline glass is a type of Uranium glass – glass with trace amounts of uranium oxide added to color the glass. This practice dates back to the early 1800’s, and reached its height of popularity from the mid to late 1800’s up until the beginning of World War II. Vasoline is not the only type of collectible glass containing uranium – others include Burmese and Custard glass. Another additive, iron oxide, is what gives vaseline glass its distinctive yellow-green color. Mosser and Fenton were two of the most prolific producers of modern-day vaseline glass.
The uranium oxide in vasoline glass causes it to fluoresce bright green under ultraviolet light (aka “black light”.) Some other glass additives fluoresce other colors under a UV light, and not all uranium glass is fluorescent, but if it “doesn’t glow green, it’s not vaseline.”
So here’s the pop quiz: Which of the collies below are vasoline glass?
Answer:
The collie on the far left and the one second from the right are Golden Opaline – the glass at the core is fluorescent, as is the glass in the head of the “Flame” collie (third from right.) The white milk glass does not react at all and looks dark.
The little basket is vasoline glass too!
So given that uranium is best known as a radioactive material, you’re probably wondering “Is it safe?” Good news – while some older vaseline glass contained alarming amounts of uranium, modern vaseline glassware gives off no more radiation than the background radiation normally found in the environment.
Want to learn more? A wealth of additional information on uranium glass can be found in this article by author and glass expert Barry Skelcher.