Antique glassware styles are as varied as manufacturers' glassware markings or hallmarks. Many manufacturers shut down production and sold company molds without first removing their distinctive markings. Some markings are easily identifiable while others are obscure, faint or absent all together. To identify antique glassware markings, collectors must research about the manufacturer and the types and patterns of glass produced. Collectors must learn other identifiable characteristics to build their collection judiciously.
Conduct extensive research on antique glassware. Invaluable books include "The Encyclopedia of Glass," "The Victorian Pattern Glass and China Book" and "Butler Brothers 1905 Glassware Catalog" (reprint). Study manufacturers like Westmoreland, Fenton, Hazel-Atlas, Imperial Glass and Fostoria Glass Company. Print out marking charts from collector sites such as www.nmgcs.org. Retrieve historical newspapers, early era ads and trade publications from a local library website. Look through general archives under research. Use Gale or Proquest research databases, which are accessed through local library subscriptions, for further research.
Distinguish Vaseline glass by its unusual yellow-green tint, easily confused with Depression glass. Hold it to an ultraviolet light. The object glows from 2 percent uranium dioxide. Search Vaseline glass manufactures Boyd and Westmoreland. Boyd's trademark is a "B" inside a diamond and found on pie vents, salt containers and other glassware. Westmoreland set a "WG" logo on its molds. In addition, other markings are embossed an intertwining "W" with a "G" or a foil label with the logo.
Explore Fenton's carnival glass. Look through past auction house catalogs obtained from collector sites or auction houses. Read "Warman's Fenton Glass: Identification and Price Guide." Distinguish a reproduction made from earlier patterns. Identify mold shapes and crimp styles. Know that some pieces were hand-decorated and signed by the artist. Recognize the company's mark---an oval with the word, Fenton or letter "F." Later, the company added the year of production to the name.
Collect Depression glass. Recognize Anchor Hocking, Hazel-Atlas, Federal and McKee. Anchor Hocking markings are an anchor with "H" superimposed down the middle. Alternately, it is an anchor inside a rectangle. Find Hazel-Atlas with an embossed "H" over an "A" or ATLAS within a rectangle. Distinguish Federal Glass by "F" inside a shield. Federal Bicentennial pieces are in darker amber, marked with "76." Find McKee with McK in a circle or PRESCUT. Earlier pieces have McKee in script.
Distinguish Fostoria Glass Company by pattern and acid etching. Most pieces from Fostoria are not marked. At the bottom of the glassware, Fostoria is etched in stenciled letters. Pieces might retain a paper label. Note its distinguishing characteristics by the weight and clarity of the glass. Most pieces were fabricated with a three-part mold and a ground glass base. Look closely for three lines from the mold.
Learn markings of Early American Pattern Glass (EAPG). Manufacturers include Boston & Sandwich Company, Heisey and Gillinder. "SANDWICH" or "B. & S. GLASS" identifies Boston & Sandwich. Heisey has a distinctive "H" within a diamond-raised mark. Some markings are faint or in discreet places such as on the glassware stem. Hand-blown pieces retain a paper label. Read "Much More Early American Pattern Glass" for specifics. "Franklin," "Nebulite" or "Gillinder" embossed inside a rectangle are markings from Gillinder and Sons.