Silver Overlay Glass:
Glass Encyclopedia

Silver overlay glass has a design in silver "electroplated" onto the glass using one of several electrolytic techniques. Like all silver, the design tarnishes and becomes black in time. It is easy to miss a lovely piece of silver overlay because the silver looks black and uninteresting. The silver can be very thin, like the Venetian decanter on the left, and this kind is sometimes called "silver deposit glass". Or it can be quite thick and even suitable for engraving.

The origins of silver overlay lie in the 19th century, but who was the first to think of using electrolysis to coat glass with silver is still a mystery. There were several patents for using electroplating techniques on glass registered from the 1870's onwards. These included Frederick Shirley USA (1879), Erard and Round for Stevens & Williams Ltd. (1889) and John Sharling in the USA (1893). But it seems that the electroplating-on-glass process was known beforehand by these people. They were patenting ways of using it.

Most of the techniques of depositing the silver involve painting the design onto the glass with flux containing silver mixed with turpentine, firing this design in a kiln, cooling and cleaning the glass and then immersing it in a solution of silver through which a tiny electric current was passed. The silver was then built up on the area where the design had been painted. An alternative method involved coating the whole surface with silver, painting the design onto the silver with a "resist" and then dissolving away the unwanted parts of the silver.

As you can imagine, it is a very expensive process. Ellen Teller in her very useful article in Glass Collectors' Digest (Nov 89) records that a decanter made in 1893 and had more than $4 worth of silver put onto a 90 cent glass blank, with nearly $5 added for labour costs.

The process of putting the silver on the glass was sometimes done by the glassworks in special decorating sections, or more often done by silversmiths on glass supplied by the glassworks. This is why pieces by Steuben, by Heisey, by Cambridge, and others who had no silver-plating facilities can sometimes be found with silver plated decoration.

There have been some very beautiful items produced with silver overlay designs. They were made in volume in England, the USA, Bohemia, Italy (Venice) and no doubt smaller amounts came from many other places. It was popular until the second world war, but a small amount continues to be produced. Recent inventions for coating the silver deposit at the time of manufacture (eg with rhodium) have successfully prevented it from tarnishing.