that uranium glass with certain mineral additions could be tempered at high temperatures, inducing varying degrees of micro-crystallization. This produced a range of increasingly opaque glasses from the traditional transparent yellow or yellow-green to an opaque white. During the Depression years, more iron oxide was added to the mixture to match popular preferences for a greener glass. This material, technically a glass-ceramic, acquired the name "vaseline glass" because of its supposedly similar appearance to petroleum jelly. Today, a few manufacturers continue the vaseline glass tradition: Fenton Glass, Mosser Glass, Gibson Glass and Jack Loranger. U.S. production of uranium glasses ceased in the middle years of World War II because of the government's confiscation of uranium supplies for the Manhattan Project from 1942 to 1958. After the restrictions in the United States were eased several firms resumed production of uranium glass, including Fenton, and Mosser; though uranium was still regulated as a strategic material. Following the Cold War, restrictions on uranium glass were completely lifted. During this time many older pieces entered the free market and new pieces continued to be produced in small quantities into the 2000s. Riihimäki Glass produced uranium glass designer pieces after World War II. See also Carnival glass Depression glass Fiestaware Sievert Uranium tile Sencer Sari References Further reading These People Love to Collect Radioactive Glass, Collectors Weekly External links Uranium Glass – The Glass Association Davidson English Pressed Glass at the Glass Museum Vaseline and Uranium Glass at the Health Physics Historical Instrumentation Museum Collection Collecting Glass compositions Uranium