Uranium in a cupboard near you!

The next time you throw a party, get out the dishes and a black light, and you might be in for a surprise!

We spoke with Conservator Sara Serban about the discovery she made while treating objects for the exhibition Celia Perrin Sidarous: The Archivist.

While we were preparing for this exhibition, a hand-blown light yellow glass napkin holder dating from approximately 1880-1910 caught our attention, due to its unusual colour and translucency. Our research into common chemical compounds used as glass colourants during this period led us to test for the presence of uranium. We examined the object under UV light and, to our delight, it fluoresced the bright green characteristic of uranium glass!

German chemist Martin Heinrich Klaproth discovered uranium in 1789, and the first documented reference to uranium glass dates from 1817. The addition of uranium to glass was popularized by Josef Riedel starting in 1834, after which it was regularly incorporated as a yellow-green colourant in all sorts of glassware. Riedel created a brilliant yellow, called Annagelb, and a brilliant green, called Annagrun, named for his wife, Anna.

Uranium was widely used in glass, glazes, and enamels on decorative objects such as buttons, jewellery, glassware, painted porcelain, and lamps until the 1940s, before the adverse effects of its radioactivity were understood.

Incorporating uranium into the glass mixture produced extraordinarily brilliant new colours capable of withstanding high temperatures. In combination with other elements, it produced a variety of colours—opaque yellow/white glass (also known as custard glass), clear brilliant yellow or amber, clear brilliant green, dark green, black, and bright red-orange (the orange-red shade of Fiesta tableware is a well-known example of the use of uranium in ceramic glazes).

While we now know that uranium is dangerous to our health, this was not always the case, and it wasn’t until 1894 that regulations were put in place regarding its use and necessary safety precautions. Prior to this, uranium was believed to have healing properties. Mildly radioactive waters and sands were used in health spas and small doses of uranium derivatives were used for the treatment of certain ailments.

The first steps in controlling the use of uranium in medical applications began in the 1890s. By the early 1940s, the United States introduced legislation outlining safeguards and controls for radioactive substances. From this point forward, the use of non-depleted uranium for glazes, enamels and glasses was discontinued worldwide.

We consulted with staff at the McGill Environmental Health and Safety Department. They generously donated their time and equipment to measure the amount of radiation emitted by the objects in our collections. With the aid of a Geiger counter, we determined that the amount of radiation emitted by the objects is extremely low, and poses no health risk. In other words, you can still come and visit us, we are not dangerous!

It is important to note that radioactive materials occur naturally in soil and rocks, and air contains traces of radon, thus exposing us to naturally occurring background radiation in our daily lives.

A quick (and fun) way to examine glass objects for uranium content is to examine them under an ultraviolet (UV), or black light, source.  If they fluoresce a bright green colour, then they most likely contain some uranium. Just remember to wear UV protection safety goggles!

I posed this question to the analysts from the McGill Environmental Health and Safety Department, and they replied that yes, it is indeed safe to drink orange juice from a uranium glass vessel.