Carnival glass was introduced by US manufacturers very early in the 1900’s.  Northwood, Millersburg, Fenton, Dugan and other American companies produced a vivid spectrum of colors and names for their hues. When the base color was sprayed with a metallic salt solution, it resulted in a finish of surface iridescence. There were two primary finish effects to the sprayed pieces: most commonly produced was a satin finish. Satin has many a multi hued reflective finish much like oil on water. Frosted, light color glass is a satin finish. Pieces with a milky edge are known as opalescent. A radium finish was introduced by the Millersburg Company and produced in limited amounts by other companies. The radium finish has a shiny, mirror like finish.   With a nearly endless spectrum of many colors and finishes, carnival glass enthusiasts enjoy a rewarding pursuit for new and known treasure.