Angel gilding is gilding glass or gold plating by electroless chemical deposition.
Chloroauric acid is dissolved in water, mixed with other chemicals and poured on clean glass that has been treated with stannous chloride.[Schweig, Bruno Mirrors: A Guide to the Manufacture of Mirrors and Reflecting Surfaces Pelham Books London 1973 ] The gold layer is delicate and usually translucent. To make an opaque, affordable and adherent mirror, a layer of silver is deposited over the gold.[Swormstedt, Tod The Angel Gild – A lost technique is rediscovered, Signs of the Times July 1988] Glass gilders use the term angel gilding to distinguish the chemical process from gold leaf gilding also known as verre églomisé.
History
Justus von Liebig, widely credited with inventing the modern process for
silvering glass, also worked on gilding glass with gold chloride. James Pratt, a British glass worker, was the first to realize that he could make affordable gold mirrors by depositing a layer of silver on top of the gold. He was granted a British patent in 1885.
[Schweig, Bruno Mirrors: A Guide to the Manufacture of Mirrors and Reflecting Surfaces Pelham Books London 1973 ] Gold mirrors and gold mirrored signs were very popular in English
public houses (pubs) in the late
Victorian era[Duthie, Arthur Louis Decorative Glass Processes 1911 republished in 1982 by Dover Publications for the Corning Museum of Glass ] and many wonderful examples of the art can be found all over Britain today.
Felix Andres, a sign painter in
San Francisco, introduced a process for spray gilding glass in 1923,
[Editor, Discovery in Glass Gilding – Something New, Signs of the Times, December 1923] but the fashion for elaborate detail in signs was changing to the modern
neon sign style and his business was not successful.
Stained glass in Chicago
Angel gilding was widely used by Chicago's stained glass studios in the 1920s and 30s
[Darling, Sharon Chicago Ceramics and Glass University of Chicago Press for the Chicago Historical Society 1973 pp 120–128 ] to make a distinctive style of stained glass for Chicago's historic bungalows. These
Prairie Style windows have a clear glass background with the designs picked out in opalescent glass and double-sided gold mirror. To make the double-sided
gold mirror the studios angel gilded large sheets of thin (1.6 mm, or 0.06 inch) glass. A worker would cut two copies of the desired shape from the glass and place the pieces back to back in a single
came.
[King, Sarah Chicago's Golden Mystery Glass Craftsman, 2008 Issue No. 206, pp 6–10] Because the pieces are gold on both sides, they catch and reflect the light whether the window is viewed from inside the house or from the street. Frank Lloyd Wright used double-sided angel gilded glass in many of his windows, including the now demolished Imperial Hotel in Tokyo.
[Hinz, Thomas A Frank Lloyd Wright's Stained Glass & Lightscreens Gibbs Smith Publisher Layton Utah 2000 p 105 ]
Today
Today angel gilding is used to gild inside
blown glass sculptures, repair Chicago's stained glass bungalow windows, create new glass signs and replicate and repair Victorian glass signs.
