Engineering:Opaline glass

Short description: Term referring to a number of glassware styles

Austrian opaline glass bowl, 1914

Opaline glass is a style of antique glassware that was produced in Europe, particularly 19th-century France. It was originally made by adding materials such as bone ash to lead-crystal, creating a semi-opaque glass with reddish opalescence.

Description

Opaline glass gets its distinctive iridescent milkiness from opacifying substances added during the mixing process, including sodium phosphate, sodium chloride, calcium phosphate, calcium chloride, tin oxide and talc. The glass can thus take on different colors and present variable shades, depending on the mixture and quantity of opacifying material substance: from white to gray, to pink, to lavender green, to golden yellow, to light blue, up to blue and black.{{citation needed|date=June 2025}

History

The first opaline glass was made in Murano in the sixteenth century, with the addition of calcium phosphate, resulting from the calcination of bones. The technique did not remain secret and was copied in Germany, where this glass was known as bein glass (lit. bone glass). Opaline glass was produced in large quantities in France in the nineteenth century and reached the apex of diffusion and popularity during the empire of Napoleon III; but the pieces made in the period of Napoleon I, which are translucent, are the most sought after by the antiques market.{{citation needed|date=June 2025} The production centers were in Le Creusot, in Baccarat, in Saint-Louis-lès-Bitche. In England it was produced in the eighteenth century, in Bristol.{{citation needed|date=June 2025} opaque opal glass objects came into fashion. At the Sèvres Porcelain Manufactory, a production line in white milk glass, decorated by hand, was experimented with, which attempted to imitate the transparency of Chinese porcelain.

17th-century Venetian opaline glasses

Most green or yellow opaline glass is uranium glass.

19th century opaline glass

Many different pieces were produced in opaline glass, including vases, bowls, cups, coupes, decanters, perfume bottles, boxes, clocks and other implements.

All opaline glass is hand-blown and has a rough or polished pontil on the bottom. There are no seams and no machine engraving, and most opaline glass is not branded or signed. Many pieces of opaline glass are decorated with gilding. Some with handpainted flowers or birds. Several have bronze ormolu mounts, rims, hinges or holders.{{citation needed|date=June 2025}

Later opaline glass

The French factory Portieux Vallérysthal in 1930 has put opal glass objects on the market in a particular blue-azure color. Some pieces have decorations in pure gold or polychrome enamels and are sometimes equipped with supports or hinges in gilded bronze (sets of plates, cruets, sets of glasses and cups, boxes, lamps, flacons, chandeliers). The blue-blue color of the glass is inspired by that of the American robin's egg.{{citation needed|date=June 2025}

Further reading

• Vincendeau, Christine. Les Opalines.  (in French)
• Amic, Yolande. L'Opaline française au XIXe siècle.  (in French)
• Lorenzetti, Giulio. fiaschetta veneziana di vetro lattimo dei primi del sec. XVI, in Dedalo : rassegna d'arte / diretta da Ugo Ojetti, Milano, Bestetti e Tumminelli, pages 248-249.  (in Italian)
• Thornton, Dora, et al. “Opal Glass in The British Museum Attributed to the Buquoy Glasshouse.” Journal of Glass Studies, vol. 57, 2015, pp. 167–82. JSTOR, http://www.jstor.org/stable/24726954. Accessed 11 Dec. 2023.