From the article linked below (Source ORAU.org):
“The accompanying photo shows two pieces of Fiestaware produced by the Homer Laughlin Company of West Virginia: a Fiesta red saucer and an ivory bowl. In each case, uranium was used to provide the color of the glaze. Although the radioactivity of both is easily detectable, that of the Fiesta red is head and shoulders above the ivory.
It is usually said that Fiestaware came in five colors when it was introduced in 1936: red, blue, green ivory and yellow. While this might be true, the oldest newspaper account that I could find, from June of that year, only identified four: “old ivory, Chinese red, blue or green.” The earliest mention of yellow that I have found was in a newspaper advertisement from January of 1937. Apparently red was the first color that the company selected when designing the product, and blue was the second (these were the colors of the Fiestaware that Andy Warhol collected). Since the idea was to mix and match, the various colors had to be compatible.
Fiesta red has always been the most popular color even though it was the most expensive. The higher price was due to the cost of the raw materials and the fact that the production of the red required a greater level of control during the firing process.
The red color was achieved by adding uranium oxide in the glaze – measurements have indicated that by weight, up to 14 % of the glaze might be uranium. How much glaze was employed per plate is unclear but it has been estimated that a single plate contains 4.5 grams of uranium (Buckley et al). Piesch et al estimated the glaze thickness at 0.2 mm.
Since this uranium could be used in the production of an atomic bomb, Fiesta red became a victim of World War II when the US government confiscated the company’s stocks of uranium. Fiesta red disappeared until 1959 when production resumed, this time using depleted uranium (DU) rather than the original natural uranium. The Fiesta red plate in the above photo was made from depleted uranium while the ivory plate was made from natural uranium.
In 1969 the entire Fiestaware line was discontinued, and in its place the company produced what was known as Fiesta Ironstone. The latter, which was only manufactured in Fiesta red (aka Mango Red), didn’t last long. It was discontinued in 1973. This was the end of Fiesta red. Years later, in 1986, a new line of Fiestaware was introduced but without the red color.”
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To see some of the Fiestaware pieces I have tested, click here.