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Glassware types and makers’ marks

Uranium, milk, carnival and Depression glass and the other kinds of old glass people find, and the marks American glassmakers pressed into their pieces.

Kinds of glass 7 symbols

Makers’ marks 8 symbols

About glassware types and makers’ marks

Most old glass found at a thrift store or garage sale is one of a handful of kinds, named for its color or finish, and much of it was pressed by American factories that put a mark on some of their pieces. The kinds of glass are mostly collectors’ names, given long after the glass was made: carnival glass was named in the 1950s, the Kent State University Museum says, and ORAU dates the name Vaseline glass probably to the 1950s too.

Kinds of glass

Uranium glass is colored with uranium and glows bright green under a black light; Vaseline glass is its transparent yellow-green form and custard glass an opaque yellow one. Milk glass is opaque, usually white, and jadeite is a green milk glass. Carnival glass is pressed glass with an iridescent finish, first made by Fenton in 1907. Depression glass is the cheap, machine-pressed colored glass of roughly the 1920s to the 1940s, often given away as a premium.

Makers’ marks

Many pieces carry no mark, and the National Depression Glass Association notes that Jeannette marked only a few early pieces of its Jadite. Others are marked plainly. Anchor Hocking’s anchor over an H was registered as a trademark in 1940, three years after the Hocking Glass Company of Lancaster, Ohio, merged with the Anchor Cap and Closure Corporation, and its Fire-King name in 1941, the year before Fire-King ovenware was first made. Fenton began making glass at Williamstown, West Virginia, in 1907, and Imperial, of Bellaire, Ohio, was one of the five major carnival glass makers. Heisey, Westmoreland, Federal and Jeannette made custard glass, milk glass and Depression glass; the Jeannette company began as a bottle plant about 1900, the Illinois State Museum says.

Glass that glows

A black light shows uranium in glass: ORAU says glass that glows a rich green contains uranium. Not everything that glows is uranium glass. Robert Brill of the Corning Museum of Glass says a weaker yellowish-green glow usually means manganese, added to clear glass as a decolorizer.

Sources

  1. Carnival Glass: The First Decade, Exhibition text, Kent State University Museum, whole exhibition text
  2. Vaseline and Uranium Glass (ca. 1930s), Paul Frame (curator), Museum of Radiation and Radioactivity, Oak Ridge Associated Universities (ORAU), introduction; identification
  3. Jade-ite, Rainbow Review Glass Journal, September 1985, National Depression Glass Association, whole article
  4. Fire-King, Rainbow Review Glass Journal, February 1981, National Depression Glass Association, article
  5. At Home...in a Century of Progress: Refrigerator dishes, Online exhibition, 1920–1950 objects, Illinois State Museum, object text
  6. Ivory and Ivorina Verde (Custard), Gallery, National Heisey Glass Museum (Heisey Collectors of America), gallery text
  7. Collectible Milk Glass ~ General Information / Overview, Glass Bottle Marks, glassbottlemarks.com, whole article
  8. Etched Depression Glass vs. Depression Glass vs Elegant, Article on the association’s website (2009), National Depression Glass Association, whole article
  9. What is Depression Glass?, Ask a Glass Question, Rakow Research Library, Corning Museum of Glass, answer
  10. Why would clear glass show a greenish glow under black light?, Ask a Glass Question, Rakow Research Library (answer quoting Robert Brill), Corning Museum of Glass, answer

Last reviewed October 8, 2026 by Rory Hansen. How we research