Mysterious light glass

「Luminescence」or「flourescence」… it’s the bewitching radiance that permeates the glass, and how many people have sought it out because of its colour, which ranges from yellow to green.

In the days when black light did not yet exist, people would hold the glassware up to the still-open morning sky to see its faint luminescence, and sigh with satisfaction.

Uranium glass was first made by glassmakers in the Czech Republic in the 1830s.
The discovery that the trace amounts of uranium in the noble clay used to colour the glass vessels fluoresced and emitted light in response to ultraviolet light is said to have been a coincidence.

The glass has a beautiful clear green colour in normal conditions, but when exposed to ultraviolet light（BLACK LIGHTS） in the dark, it emits a more brilliant and mysterious fluorescent colour.

Since then, vessels made from this glass have captivated many people and spread from Europe to the USA as a fascinating luxury item, eventually becoming known throughout the world.

Uranium glass imported to Japan in 1899.　At the time, when Western-style architecture was on the rise and the domestic production of glass was proceeding at a rapid pace, uranium glass came as a particular surprise.

The craftsman Iwaki-Takijiro (1857-1915), a pioneer of Japanese glass artisanship, introduced the manufacturing technology from the USA and succeeded in producing a prototype after much hard work.
Following the global trend, Uranium glass became popular from the Taisho period to the early Showa period.

Uranium glass from the USA is often yellowish green, while uranium glass in Japan is said to have been greenish and somewhat pale luminescent.

Globally, there are various types of uranium glass from different manufacturing countries and brands, such as those with a bluish green or a white cloudy part.

「Fairy Wood Glass Museum / 妖精の森美術館」, located in Tomata County, Okayama Prefecture, mid-western Japan, is a museum dedicated to uranium glass.

Uranium glassware production was proposed as a local speciality development after uranium deposits were discovered and mined in the area in 1955.　The handmade glassware, which combines traditional beauty with a modern flair, became very popular.

The Fairy Forest Glass Art Museum was established in this vein, centred around the collection of Dr Tomabechi-Ken Radiology.

The museum is small, but has a large collection of rare domestic and foreign uranium glassware from the 19th and 20th centuries, which emit a mysterious light.
In the adjoining area, visitors can try their hand at glassblowing and buy glassware.

The name uranium may give some people some puzzlement.　As you know, uranium is a radioactive substance. Japan is the only country in the world to have been exposed to nuclear weapons, and we are well aware of the horror of the radiation damage caused by subsequent incidents and accidents.

In addition, since the end of World War II, the trade in nuclear material has been severely restricted due to the perceived dangers of the material.

This is also the reason why most glassware production using uranium glass ceased after the 1950s.

Anderson stone Uranium dioxide.

However, the uranium contained in uranium glass is extremely small and the amount of radiation emitted from it is said to be about the same as that from the cathode ray tubes of TVs and the radiation that falls from the sky every day, which we are so familiar with in our daily lives.

It is also said to be at the same level as the radioactive isotopes in the mineral potassium, which is necessary for our bodies.

Although not uranium, when I used to collect old camera lenses as a hobby, I owned a lens that contained thorium, one of the isotopes.　Lenses containing thorium were popular with old enthusiasts because they seemed to have excellent transmission properties.　When I asked about the dangers of radiation, I was told that even the values measured directly on the lenses with a measuring device were well below the permissible levels for the human body.

In any case, I have never heard of or seen any specific reports of health damage from exposure to these products. It is probably nothing to worry about.

Even after the deregulation of the uranium trade, the manufacture of uranium glass was in decline as the price of uranium itself soared.

In recent years, attempts to revive it have been made in many countries due to its mysterious fluorescent beauty and admiration for old techniques.　Most of them tend to be expensive due to the time and cost involved in one-off production and may not be suitable for everyday use, but the mysterious fluorescence, which cannot be obtained from other glassware, continues to attract new fans.

「Fairy Wood Glass Museum」is holding the special exhibition「Forms of Light / ひかりのかたち展」until Monday 12 May 2025.

This is a unique exhibition for those with an interest in glass art and beautiful and mysterious glassware.　The Fairy Wood Glass Museum is in a somewhat remote location, but may appeal to those planning to visit western Japan…