Uranium in glass, glazes, and enamels: History, identification, and handling

Donna Strahan


Uranium was used as a colorant in glass, glazes and enamels of decorative and functional objects for roughly one hundred years before the adverse effects of its radioactivity were understood. It can be found in objects ranging from souvenirs, trinkets, everyday dishes and glassware, to exotic one-of-a-kind artworks, decorative lamps, and stained glass. Painted porcelain and enamels employed uranium colorants because of their ability to withstand high firing temperatures and because of the variety of colors they produced. Colorants containing uranium have also been used in enamel restorations.

Elemental uranium was first discovered in 1789. Between its discovery as a colorant for glass/glazes in the 1840’s, and the identification of its hazards in the 1940’s, uranium was extensively used by the glass and ceramics industry, as well as by numerous artists. It was particularly popular in the later half of the 19th century in Europe, the United States, and Japan. Restrictions were placed on the use of uranium in 1942 and it soon disappeared from workshops.

The purpose of this paper is to bring the widespread use of uranium in objects to the attention of practicing conservators and museum personnel who routinely work with decorative and functional arts. Whereas much work has been done on radioactive mineral specimens, little has been reported on decorative objects. Those who are aware of uranium as a colorant usually think of bright red-orange and yellow glazes and glasses, but it is also used for dark-green and black. Topics covered in this paper are uranium colorant manufacturing methods, historical uses, detection and identification methods, health risks and hazards, and suggested display and storage methods. A balance will be made between understanding the hazards and not over-reacting.

1999 | St. Louis | Volume 6