Yes the Jack Frost treatment was introduced in the late 20s & although the manufacturer is Tiffin (as in Tiffin, OH)...to be technically correct is made made at Factory K in Pittsburgh, PA. All USG (United States Glass Co.) products (no matter which factory actually made the product) were named Tiffin (which was actually Factory R) after Sept. 1927. Before 9/27 products were marked USG or USGco. Change had to do with marketing products.