The weird history of our dangerous relationship with uranium

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Uranium incorporated for color causes fluorescence under ultraviolet light. Credit: James L. Amos/Getty Images

Excerpted from Chain Reaction: The Hopeful History of Uranium by Lucy Jane Santos with permission from Pegasus Books. November 2024.

In the US in the late 1880s, La Belle Glass Company developed what became known as Ivory or Custard glass by increasing the concentration of uranium oxide, which made the effect more opaque. Heat-sensitive chemicals, such as gold, were added to the mix, which, when reheated during the manufacturing process, resulted in a shading effect that ranged from clear yellow to milky white at the edges. Meanwhile, Burmese glass was developed by the Mount Washington Glass company. The recipe included white sand, lead oxide, purified potash, niter, bicarbonate of soda, fluorspar, feldspar, uranium oxide and colloidal gold. This formula produced an opaque glass that came in different shades, from pink to yellow. It is thought that its name was bestowed after Queen Victoria remarked that it reminded her of a Burmese sunset.

And while there were many different shades, it was the yellowish-green effect that became the most popular choice among buyers. Much later it became popularly known as Vaseline glass, due to its supposed resemblance to the famous brand of petroleum jelly. There were also plenty of other companies who were using uranium to colour their glass at this time. The various producers were vying with each other to produce new colours, effects and transitions among an atmosphere of commercial secrecy.

However, one of the strangest uses for this colouring was noted in 1847, when Scientific American reported that uranium, along with platina, titanium and cobalt, had a secondary application as a colouring agent for artificial teeth made from feldspar and quartz. By incorporating uranium as a final step in the glass-making process, just before being fired, the teeth were given an orange-yellow hue. While it sounds a bit strange that this was the desired effect, throughout history dentures and false teeth had been made with ivory, gold, silver, mother of pearl or enamelled copper. It was only later in the nineteenth century, mainly with the introduction of porcelain teeth, that looking natural or realistic was a desirable quality in artificial teeth. And, even then, the technology wasn’t quite up to scratch. Artificial teeth looked unnatural, and it was only due to a robust … Read More