Tiffany made the first iridized art glass. Their formula was EXPENSIVE. The iridization was in the glass mixture, not sprayed on the glass. Fenton came up with a cheaper way of making iridized art glass and introduced their line of "imitation" Tiffany glass in Oct of 1907. It was an instant success and other companies such as Northwood, Dugan, Imperial and Millersburg soon followed Fenton's lead. Carnival glass was in it's heyday from about 1908 to 1920. Tiffany was not too happy about it. One well to do lady said it best, "When the maid can afford similar glass, I don't want it."
The industrial revolution hit the glass industry in the early 1920's. Companies like Jeannette and Indiana switched to machinery instead of hand presses. They could crank out nearly 50 ton of glass daily even back then. The economy was going downhill...............stock market crash and then the depression. A great many of the hand making glass companies went under. The first depression glass patterns came out in the mid 1920's and kind of took over. They were CHEAP and very colorful machine made glass.
So what to do with all the warehouses full of iridized glass? Americans no longer wanted it. The overseas markets were drying up too. So most of it was sold to the traveling carnivals for pennies on the dollar to be used as game prizes, thus the name Carnival Glass.
FYI: The traveling carnivals actually did well in the depressed 1930's and hard World War II times of the 1940's. No matter how broke folks were, they always found the money for some entertainment. When the traveling carnival hit town, out came the stashed coins. Every guy took his best girl and tried to win her a piece of "fancy glass". And those memories and treasures were admired and then tucked away. If a piece of carnival glass could talk, oh what a story it would have to tell (smile).
Collecting carnival glass is an AWESOME hobby and there is always a great selection available on Ebay! CARNIVAL GLASS on Ebay