Coveted uranium glass dishes glow magically—could you believe they were still made in the 1970s?
Uranium glass is glass that has been dyed yellow with uranium and that glows green under ultraviolet light. Items made from uranium glass are still slightly radioactive and not recommended for storing food.
Finnish glass artist Nanny Still’s famous yellow ‘Grapponia’ dishes and other greenish-yellow glowing glassware manufactured by Finnish glass company Riihimäen Lasi are now coveted collector’s items. But did you know that uranium glass enthusiasts roam flea markets with UV flashlights and sensitive radiation meters? You see, the yellow glass is dyed with radioactive uranium, which produces an astonishing magical glow under UV light.
Uranium salts were used to dye glass from the 1830s until the 1940s. During the Cold War, however, civilian use of uranium was significantly restricted, and it was gradually replaced with more affordable dyes. The uranium content in the glass was usually between 0.1% and 1.5%, but in early 20th-century pieces, it could be as high as 25%.
Concerns about the safety of uranium glass are understandable, but the radioactivity of decorative glassware is not harmful to health. The glass emits minimal radiation, and people don’t usually handle these dishes continuously. Nevertheless, the Radiation and Nuclear Safety Authority of Finland does not recommend using glassware containing uranium for storing food. With a sensitive Geiger counter, you can obtain readings from the surface of the item that are clearly higher than background levels; however, the radiation doesn’t extend far. It’s safe to admire these treasures through the glass of a display cabinet.
