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Artifact of the Month: Window Glass

Conservator Elise describes evidence for windows from the site

Author: Elise Carroll, Conservator

Window glass
Window glass from site 31CR314

Previously, we have discussed many different types of glassbeadsstemwareonion bottlescase bottles, and flacon bottles, as well as glass conservation. We have also discovered glass from windowpanes. When someone thinks of a wooden sailing ship, windows are not necessarily the first thing that comes to mind. Bulky and distinct items such as masts, sails, beams, and planks are what usually come to mind when thinking of the Age of Sail, but at the stern of many vessels was a series of windows. Glass panes were commonly seen along the transom of a ship, in the stern cabin, and occasionally found as part of lanterns, illuminating areas within the vessel. 


Lead window came
Window came from the site

In archaeological contexts, windowpanes, and potential windowpanes, have been identified on many contemporary archaeological shipwreck sites. Swan was a warship that sank in Scotland in 1653. Windowpanes were discovered alongside the lead window came, or the lead strips that held the separate pieces of window glass together. Another potential window glass or mirror glass was found on the late 17th-century shipwreck of La Belle in the Gulf of Mexico. Window glass and mirror glass can be difficult to distinguish without a distinct reflective coating. The glass fragments recovered were flat, likely cast picture or mirror glass


Pontil in window glass
Window pane with pontil

Unlike flat glass, the windowpanes found on our site are crown glass or bullseye glass. Bullseye glass was one of a few methodologies for manufacturing glass that could support a large pane. This manufacturing style began in the 1330s in Normandy by Philippe de Cacqueray and was commonly used for window glass. Bullseye glass was made through blowing a bubble in molten glass and attaching it to the end of a pontil rod. Then reheating the balloon, the pontil is spun rapidly causing the ballooned glass to turn into a thin disk using the force of the spinning. The bullseye/crown is formed on the glass where the pontil was attached because it was thicker and left a scar at the attachment point. This attachment area literally caused a bullseye effect, which you can see on both QAR643.001 and QAR1591.000. 

Diderot glass
Historic glass manufacturing

Window glass is situated mainly towards the stern portion of the site and located near fragments of window came. The location of the windowpanes, in context with the lead window cames, suggests that these panes likely belonged to windows at the stern of the vessel.  


Bruseth, J. E., A. Borgens, B.M. Jones, and E.D. Ray. 2017. La Belle the Archaeology of a Seventeenth-Century Ship of New World Colonization. Texas A&M University Press.
Martin, C. 2017. A Cromwellian Warship Wrecked off Duart Castle, Mull, Scotland, in 1653. Society of Antiquaries of Scotland.
Ollivier, B., and D.H. Roberts. 1992. 18th Century Shipbuilding: Remarks on the Navies of the English and the Dutch from Observations made at their Dockyards in 1737. Jean Boudriot Publ.


-Glass from site 31CR314. Image by NC Dept of Natural and Cultural Resources.
-Lead window came from site 31CR314. Image by NC Dept. of Natural and Cultural Resources.
-Glass pane with pontil from site 31CR314. Image by NC Dept of Natural and Cultural Resources.
-Unsigned, Verrerie en bois, ou grande verrerie a vitres ou en plats Planche II, Encyclopédie, ou dictionnaire raisonné des sciences, des arts et des métiers, etc., eds. Denis Diderot and Jean le Rond d'Alembert. University of Chicago: ARTFL Encyclopédie Project (Autumn 2022 Edition), Robert Morrissey and Glenn Roe (eds): Accessed on 5 April, 2023

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