Uranium Glass: History, Identification, UV Glow & Collecting Guide
Few forms of collectable glass can transform as dramatically as uranium glass.
In ordinary daylight, it may appear yellow, citron, green, amber or almost colourless. Place the same piece beneath ultraviolet light and it can come alive with an intense fluorescent green glow. A carefully arranged cabinet of uranium glass can create a particularly impressive display, especially in a darkened room or at night.
Uranium glass was produced across Europe, Britain, Scandinavia and the United States in an extraordinary range of forms. These include drinking glasses, bowls, plates, vases, candle holders, dressing-table pieces, decorative objects, beads and modern art glass.
Today, collectors value uranium glass for its colour, unusual history, variety and unmistakable reaction beneath ultraviolet light.
What Is Uranium Glass?
Uranium glass is glass made with a uranium compound added to the molten glass mixture, principally as a colourant.
The amount used was generally small, although it varied between manufacturers, countries and production periods. Uranium could produce shades ranging from pale yellow and citron through yellow-green and rich green. Additional ingredients and different glassmaking techniques allowed manufacturers to create many other colours and degrees of transparency.
The uranium compound within the glass is also responsible for its most famous feature: vivid green fluorescence when exposed to suitable ultraviolet light.
Uranium glass is an umbrella term. Vaseline glass, canary glass and citron glass are descriptions associated with particular colours or appearances, rather than names for entirely separate materials.
The Early History of Uranium Glass
Uranium-bearing material has been detected in ancient glass, including a fragment from a Roman-period mosaic. However, this should not be confused with the organised commercial production of uranium glass that developed during the nineteenth century.
The modern history began after German chemist Martin Heinrich Klaproth identified uranium in 1789. European glassmakers subsequently experimented with uranium compounds as colourants, and recognised commercial manufacture was established during the 1830s.
Bohemian glassmaker Franz Xaver Riedel is closely associated with this early development. Yellow and yellow-green varieties produced by Riedel were known as Annagelb and Annagrün, reportedly named in honour of his daughter Anna Maria.
From Bohemia, the use of uranium spread among European and British glassworks. By the late nineteenth and early twentieth centuries, uranium-coloured glass was being produced in numerous countries and in an increasingly wide selection of decorative and practical forms.
What Are Citron, Canary and Vaseline Glass?
Several historic names are used when describing yellow or yellow-green uranium glass.
Citron glass generally describes glass with a clear yellow or lemon-yellow colour.
Canary glass refers to bright transparent yellow glass, reminiscent of the colouring of a canary.
Vaseline glass traditionally describes transparent or translucent yellow to yellow-green uranium glass whose appearance was likened to the petroleum jelly sold during the period.
The name Vaseline glass is sometimes used for all uranium glass, particularly in the United States. More precisely, however, it describes the familiar transparent yellow or yellow-green variety rather than every colour of glass containing uranium.
Not every yellow or green piece of glass contains uranium, and uranium glass is not limited exclusively to these colours. A positive and characteristic UV reaction is therefore much more useful than colour alone.
How Was Uranium Glass Manufactured?
Like other traditional glass, uranium glass was made by heating a mixture of silica, fluxes and stabilising ingredients until they formed a molten material.
A uranium compound, commonly described in general terms as uranium oxide, was added to the batch as a colourant. The ingredients, furnace conditions, uranium concentration and addition of other metallic colourants influenced the finished colour and opacity.
Once molten, the glass could be blown, moulded, pressed, cut or otherwise worked into household and decorative objects.
Uranium was normally incorporated throughout the glass rather than applied only to its surface. This distinguishes uranium glass from ceramic wares whose uranium-bearing colour may be present in a surface glaze.
Why Does Uranium Glass Glow?
Uranium glass fluoresces because uranium compounds within the glass absorb energy from ultraviolet light and release part of that energy as visible green light.
The process is fluorescence rather than radioactivity making the glass visibly glow.
The green light normally disappears almost immediately when the UV source is removed. Uranium glass does not generally continue glowing in darkness in the way that phosphorescent, or “glow-in-the-dark”, material can.
The vivid fluorescence can reveal moulded patterns, cut decoration and sculptural contours that are much less obvious in normal daylight. This dramatic transformation is one of the principal reasons uranium glass has developed such a dedicated collecting following.
How to Identify Uranium Glass
Colour can provide an initial clue, but it does not establish that a piece contains uranium.
Traditional uranium glass is frequently:
• Pale lemon yellow
• Citron yellow
• Yellow-green
• Apple green
• Deep green
• Amber or honey coloured
• Clear or only lightly tinted
• Opaque or translucent in certain specialised glass types
The most accessible identification method is examination with an ultraviolet torch or lamp. Uranium glass normally produces a strong, clear and fairly even green fluorescence through the body of the glass.
A 395 nm UV light is widely used by collectors because it can help distinguish the characteristic uranium reaction from some other fluorescent glass colourants. A 365 nm light can also be useful and may reveal reactions that appear weaker under 395 nm illumination.
For careful examination, it can be worthwhile comparing the piece beneath both wavelengths.
UV-Reactive Glass Is Not Always Uranium Glass
A glow beneath ultraviolet light does not automatically prove that an object is uranium glass.
Other glass ingredients can fluoresce in different colours or under different UV wavelengths. Manganese, selenium, cadmium and certain other compounds can all produce reactions.
Manganese glass is a particularly frequent source of confusion. It can display a pale or subdued green response, especially beneath a 365 nm light, but the reaction is often weaker and less saturated than the brilliant green normally associated with uranium glass.
Collectors should consider:
• The colour of the glass in daylight
• The strength and consistency of its fluorescence
• Whether it reacts beneath 395 nm, 365 nm or both
• The object’s age, form and likely manufacturer
• Any moulded, etched or applied maker’s marks
• Catalogues and documented production colours
• Instrument testing when definitive confirmation is important
A Geiger counter can detect radioactivity in many uranium-glass objects, but readings vary according to the instrument, the glass composition and the distance from the object. A UV examination is usually the most practical first test for collectors.
The Rise of Collectable Uranium Glass
Uranium glass reached a broad popular market during the late nineteenth and early twentieth centuries.
Glassworks produced elegant Victorian tableware, decorative pressed glass, Art Nouveau forms, Art Deco designs and inexpensive household glass. During the interwar and Depression periods, uranium-bearing glass appeared in many practical objects intended for everyday homes.
Production was interrupted or greatly restricted during the Second World War as uranium became a strategically controlled material. In the United States, uranium glass production largely stopped during the war years and later resumed using depleted uranium after restrictions were relaxed.
Uranium glass never completely disappeared, but post-war production was more limited. Some European, Scandinavian and American manufacturers continued using uranium compounds, while modern glassmakers have occasionally revived the material for decorative or artistic work.
Scandinavian Uranium Glass
Scandinavian glass deserves an important place within the broader story of uranium glass.
Finnish, Swedish and other Nordic glassmakers combined striking colours with the restrained forms, strong textures and practical modernism for which Scandinavian design became internationally recognised.
Riihimäen Lasi of Finland is one of the best-known Finnish glass manufacturers encountered by collectors. Established in Riihimäki in 1910, the company produced household, pressed, decorative and art glass across much of the twentieth century.
Some Riihimäen Lasi designs were produced in UV-reactive yellow or green glass. These pieces combine the excitement of uranium fluorescence with the clean geometry and distinctive moulded surfaces associated with post-war Scandinavian glass.
Uranium glass by Riihimäen Lasi and other Scandinavian makers belongs comfortably within a general uranium-glass collection. The maker, designer, pattern, production date and documented colour remain important when assessing an individual piece.
Why Did Manufacturers Stop Using Uranium?
Uranium glass did not disappear because every piece was suddenly judged too dangerous to own.
Its decline resulted from several factors:
• Uranium became strategically important and tightly controlled during and after the Second World War.
• Wartime restrictions interrupted established manufacturing.
• Production costs and regulations changed.
• Consumer preferences moved toward different colours and styles.
• Alternative commercial glass colourants became readily available.
• Some manufacturers closed or moved away from decorative glass production.
Limited uranium-glass production resumed after wartime restrictions were relaxed, sometimes using depleted rather than natural uranium. Small-scale production has continued in certain countries, although it is far less common than it once was.
Is Uranium Glass Safe?
Uranium glass is mildly radioactive, but intact pieces are generally regarded as presenting a very low risk during normal handling and display.
The Oak Ridge Associated Universities Health Physics Museum notes that the estimated radiation exposure associated with uranium glass is low and that these objects are generally not harmful under ordinary handling conditions.
Nevertheless, collectors should apply sensible care:
• Keep pieces intact and avoid grinding, drilling or sanding the glass.
• Do not deliberately create or inhale glass dust.
• Handle broken or chipped glass carefully because sharp glass itself presents an immediate hazard.
• Do not allow children to play with uranium glass.
• Avoid using damaged vintage glass for food or drink.
• Do not store food or acidic liquids in antique uranium glass for prolonged periods.
• Use valuable or historically significant examples primarily for collection and display.
There is a difference between occasionally handling an intact collectable and modifying, crushing or working the material. Ordinary display does not create airborne contamination, but cutting or grinding any old glass without appropriate controls is unwise.
As with other antique tableware, unknown manufacturing standards, wear, repairs and surface damage provide additional reasons to treat collectable examples as decorative objects rather than everyday food vessels.
How to Display Uranium Glass
Uranium glass can be attractive in daylight, but UV lighting reveals its most spectacular character.
A dedicated cabinet can create a vivid green display while protecting the glass from knocks, dust and handling. Dark or black backgrounds increase the apparent intensity of the fluorescence, while clear glass shelves allow UV light to reach multiple levels.
Useful display considerations include:
• Position UV lighting so it illuminates the glass evenly.
• Avoid concentrating excessive heat inside a closed cabinet.
• Conceal visible cables and light fittings where practical.
• Use secure shelves capable of holding the collection’s weight.
• Leave space between pieces so their shapes remain distinguishable.
• Keep tall or heavy pieces away from shelf edges.
• Use museum wax or another appropriate removable stabiliser where needed.
• Limit unnecessary exposure to strong sunlight, which may affect labels, packaging and surrounding materials.
A switchable UV cabinet allows the collection to be enjoyed in both ordinary light and fluorescent display. At night, even a relatively small group of pieces can produce a remarkable visual effect.
What Uranium Glass Can Collectors Find?
Uranium glass was made in a much wider variety of objects than many beginning collectors realise.
Examples include:
• Bowls and serving dishes
• Plates, saucers and cake stands
• Drinking glasses and goblets
• Jugs and decanters
• Vases and flower holders
• Candle holders
• Dressing-table bottles and trays
• Knife rests and table accessories
• Salt cellars and condiment sets
• Jewellery, beads and buttons
• Animal figurines and decorative objects
• Art glass and Scandinavian modernist designs
Collectors may specialise by country, maker, colour, period or form. Others assemble a varied cabinet chosen principally for the strength of the glow and the overall effect of the display.
What Determines the Value of Uranium Glass?
The presence of uranium does not automatically make every object rare or valuable.
Important factors include:
• Identified manufacturer or designer
• Pattern and production period
• Scarcity of the particular form or colour
• Quality and intensity of fluorescence
• Condition
• Size and visual impact
• Original labels, boxes or documentation
• Provenance
• Current collector demand
• Whether the attribution is documented or merely assumed
Common pressed-glass pieces can remain relatively affordable, making uranium glass an accessible collecting field. Scarce colours, sought-after patterns, notable designers and documented art-glass forms can command considerably higher prices.
Condition should always be assessed in ordinary light. Strong fluorescence can distract from chips, cracks, cloudiness, scratches, manufacturing flaws or later repairs.
Questions to Ask Before Buying Uranium Glass
Before purchasing a piece, consider asking:
• Has it been tested beneath ultraviolet light?
• Which UV wavelength was used?
• Does the entire body fluoresce or only part of the surface?
• Is the maker or designer identified from a reliable source?
• Are there any chips, cracks, scratches, bruises or repairs?
• Is there internal cloudiness or staining?
• Are the base and rim smooth and undamaged?
• Is the colour accurately represented in ordinary daylight?
• Are both daylight and UV photographs available?
• Is the piece being sold for display or represented as functional tableware?
Clear daylight and UV photographs are particularly valuable when buying online.
Collecting Uranium Glass at TMC Emporium
TMC Emporium has handled numerous examples of uranium and UV-reactive glass over the years, ranging from practical vintage tableware to highly decorative European and Scandinavian designs.
Our evolving collection includes uranium glass selected for its form, colour, condition, identified manufacture and visual impact under ultraviolet light. When available, listings include both ordinary-light and UV photographs so collectors can appreciate the glass in its two very different appearances.
As further examples are discovered, the collection will continue to develop across different makers, countries and periods rather than being restricted to a single manufacturer.
EXPLORE SECTION
View our current selection of vintage and collectable uranium glass, including European and Scandinavian examples tested beneath ultraviolet light.
Browse more vintage and collectable uranium glass available from TMC Emporium: