The Wistarburgh factory was America’s first successful glassworks. Since it operated largely prior to the American Revolution, little is known about its products, and confusion surrounds the authenticity of some of the objects attributed to this factory. However, analysis of alkali-lime glass sherds from the glassworks site shows that green Wistarburgh bottle glass is much more calcic and is enriched in various trace elements (notably the rare-earth elements) compared with later south Jersey glass for which analytical data are available. The compositional data indicate that Wistarburgh’s proprietors made use of a batch recipe containing approximately 68 wt.% local sand, 24% dolomitic limestone, and 3% each of soda ash and potash. In addition to green bottle glass, blue, aquamarine, and colourless potash–lead glass and colourless potash glass were also recovered from the Wistarburgh factory site, suggesting that a range of specialized glasswares was produced by this factory.