The process of staining consists of coloring the surface of a piece of glass by covering it with metal oxides applied with a brush. After firing, the surface emerges covered with a translucid layer of yellow (silver staining) or red (copper staining).

This technique is the legacy of the Bohemian glassmaker Friedrich Egerman (1777-1864). Painter, technician, and an avid researcher, he performs several experiments with blanket coats of color like the opaque white enamel called “mother of pearl” before discovering silver staining in 1816 and copper staining in 1832. Egerman remains the sole keeper of the secret of producing copper staining until 1840, when the secret is forcibly taken from him by unscrupulous competitors who then flee to France. This explains how the technique was sold to the Saint Louis glassworks after 1840. The process was also put into practice by Baccarat beginning in 1860, notably for the World’s Fair of 1867.

PETROVA Sylva, OLIVIE Jean-Luc, “Verres de Bohême” 1400-1989”, Flammarion, Musée des arts décoratifs, Paris, 1989