Uranium Glass
Uranium, fluorescent and Vaseline Glass
Above: Two green uranium glass vases by Sowerby of Gateshead, made in the 1930's
In this article Fluorescent Glass and Uranium Glass are defined very simply as any kind of glass which has uranium in it. I have avoided the term "Vaseline Glass" because there are conflicting interpretations of what it means. And I recognise that this definition includes some opaque glass as well as translucent and opalescent green and yellow glass.
During the early 19th century glass makers in Central Europe started to use uranium as a good way to make yellow and green glass. In 1789 Martin Klaproth in Germany had first recognised uranium as a chemical element, and is said to have added it to glass as a colourant. But it was 50 years later that glassmakers in Bohemia, seeking new colours in a highly competitive market for glass, started to use uranium.
Bohemia became part of the Austrian Empire with the peace settlement of 1815, after the Napoleonic wars, and the glass trade prospered under peaceful conditions until the 1850's. This area which had numerous glass-works in that period, is now split between The Czech Republic, Austria, and Germany.
Above: The same Sowerby Bullrushes bowl (top picture) glowing under ultraviolet light
The most striking thing about fluorescent or uranium glass is that it is radio-active. If you apply a geiger-counter you will get a positive reading. If you shine an ultra-violet light onto it, you will get a fluorescent green glow, like the picture above. But the levels are not, so far as we all believe, in any way harmful. Two pounds of uranium oxide were typically added to around 184 pounds of other constitutents. Tests conducted by Jay Glickman (reported in his book "Yellow-Green Vaseline: A Guide to the Magic Glass) and separate tests by Frank Fenton, of Fenton Glass, have shown that the radiation levels from even large quantities of uranium glass at close quarters are no more harmful than those associated with television sets or microwave ovens.
If you get an ultra-violet torch, sometimes called a "black light" from a stamp collecting shop or a glass collectors' supplier, and shine it on uranium glass, the object will fluoresce beautifully (don't look at the light directly though, strong ultra violet light can be bad for the eyes).
When added to glass, usually as an oxide, uranium produces colours varying from amber through all the shades of yellow, to bright apple green, depending on the glass mixture. When added to a glass mixture with a very high lead content (over 70% lead oxide) it produces a deep red colour (not a practical commercial proposition, however).
Josef Reidel is usually credited with inventing uranium glass in 1830 under the names "Annagrun" for uranium yellowish- green glass, and "Annagelb" for uranium yellow glass, naming them after his wife Anna Maria. His factory, Dolny Polubny in Bohemia, made these kinds of uranium glass from 1830 to 1848.
In 1836, after a visit to Bohemia, a French society for encouraging industry offered prizes for imitations of Bohemian glass. In 1838 the Choisy-le-Roi factory in France was producing uranium glass. In 1843 the French glassworks, Baccarat, started making uranium glass, which they called "cristal dichroide" and also introduced an opaque apple-green version which they named "chrysoprase".
Right: Typical uranium glass from Bohemia, made in the 1840's
During this early period, uranium glass was normally heavy coloured crystal glass with beautiful facet cutting and polishing. It was also sometimes decorated with enamel or engraved.
When pressed glass became popular later in the century, uranium was often used to make green and yellow shades, by factories all over the world, including the US and England.
During the latter part of the 19th century, some glass with uranium was made with heat sensitive chemicals which turned milky white when reheated, producing a shading effect from yellow to milky white at the edges. This kind of glass is often called "vaseline glass" today, because of its similarity to the ointment of that name (which used to be a yellowy colour, but nowadays is more or less white, just to confuse the glass collectors). Davidson's lemon pearline contains uranium and is usually classified as one kind of "vaseline glass". There is an article and pictures of Davidson's glass on this website at http://www.glass.co.nz/Davidson.htm
Left above: Pearline compote by Davidson's, 1890
Uranium was a common source of yellow and green colouring for over a hundred years. In the 1940's it was banned as a glass constituent because uranium was used to make the atom bomb, there were fears for the health of glassworkers, and both US and UK Governments wanted to restrict access to uranium for military reasons. The British Government even confiscated large quantities of glass-making materials which had uranium in them just after the war. Bagley's of Yorkshire lost three tons of confiscated materials.
During the 1950's these restrictions were lifted and some companies now use uranium as a colourant occasionally. However there are other chemicals which can now be used to produce the same colours, and the price of uranium oxide is high, so there is not likely to be a ressurgence of popularity for uranium glass manufacturing. There are also rigorous control regulations covering protective clothing for workers, lead shielding for storage areas, and monitoring of radiation. Small amounts have been made, usually small items and usually made for collectors. Boyd Glass and Fenton Art Glass are two USA companies that produce uranium glass items today.
It is not widely known that the "Burmese" glass made by the Mount Washington Glass Company from the mid 1880's, contained uranium. The formula for Burmese glass, patented by Frederick S. Shirley in December 1885, is:
- 100 pounds white sand
- 36 pounds lead oxide (refined)
- 25 pounds purified potash
- 7 pounds niter
- 5 pounds bicarbonate of soda
- 6 pounds fluor-spar
- 5 pounds feldspar
- 2 pounds uranium oxide
- 1.5 pennyweights colloidal gold
The gold gave Burmese glass its heat sensitivity, so that the parts which were re-heated during manufacture turned salmon colour, whilst the rest of the object remained creamy yellow.
The picture on the left shows the green Sowerby three-cornered vase (from the picture at the top of the page) photographed in ultra-violet light. Isn't it beautiful? The pattern of chrysanthemums was sandblasted to give a matt finish, the rest of the vase, with its art deco angular pattern, was left shiny. Sowerby's (of Gateshead in the North East of England) were making beautiful pieces of pressed uranium glass in the 1930's; but the war of 1939-45 put an end to all that.
If you are looking for uranium or vaseline glass, you can usually find a selection on offer on ebay. Click here to see Uranium Glass for sale now.
Here are some very helpful books on uranium glass. Click on the book cover or title to read more about that book.
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