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In 1685 German glassmaker Andreas Cassius published his book De Auro in which he described his method of producing a red precipitate of stannic acid with gold that came to be known as the “Purple of Cassius.” Cassius first reported his discovery in 1676 and in 1670 a Potsdam Chemist and glassmaker named Johann Kunckel von Lowenstern created pieces of ruby glass. He attempted to keep his production methods a secret. Part of the mystery was that initially in production the glass appears gray and turns red only when reheated. He eventually published the results of his experiments in his famous book Ars Vetraria Experimentalis in 1679.In 1685 German glassmaker Andreas Cassius published his book De Auro in which he described his method of producing a red precipitate of stannic acid with gold that came to be known as the “Purple of Cassius.” Cassius first reported his discovery in 1676 and in 1670 a Potsdam Chemist and glassmaker named Johann Kunckel von Lowenstern created pieces of ruby glass. He attempted to keep his production methods a secret. Part of the mystery was that initially in production the glass appears gray and turns red only when reheated. He eventually published the results of his experiments in his famous book Ars Vetraria Experimentalis in 1679.
According to Cassius, gold chloride, a colloidal gold solution produced by dissolving gold metal in Aqua Regia (nitric acid and hydrochloric acid) in the glass mixture was needed. Tin (stannic chloride) was also added in tiny amounts, making the process both difficult and expensive. Depending on the composition of the base glass, the ruby color may develop during cooling, but the glass may have to be reheated to ‘strike' the color."
Today's studio glassmakers can buy their gold ruby glass in rods from specialty suppliers. This takes the guesswork out of the chemistry of creating the color but is also more costly. In order to reduce the overhead expense, ruby glass is often cased glass with a layer of crystal on top of the ruby colored layer. Another type of cased glass places the colored glass on top. A popular technique in the Bohemia region of Europe was to then cut or etch a pattern in the glass. Flashed glass, also is often decorated with this technique. In flashing, the clear glass is quickly dipped in a bath of colored glass, creating a thin coating.
Fast forward to the 19th century and another glassmaker in Bohemia quickly became known for beautiful decorated glassware.
Ludwig Moser was born in 1833, the son of Lazar Moser, the first Jew to be given trade and traveling papers. Ludwig was apprenticed and trained as both a glass-cutter and engraver and also studied painting. In 1857 he purchased a restaurant in the Health Spa Resort community of Karlsbad, which he converted into an engraving studio. As customers flocked to buy his quality pieces, he expanded by hiring dozens of workers and opened another workshop to the north in Meistersdorf.
While Moser's initial glassware relied on colored blanks purchased from other studios in Bohemia, he became well known for his distinctively decorated enameled colored glass. His work displayed at the 1878 Paris International Exposition featured gilded glass pieces decorated with Islamic and Japanese motifs.
Some of Moser's pieces from the early 20th century are characterized by rare earth tones of color, which shift in depth and are further enhanced with deep faceted coloring and enamels. The gold ruby colors of the Moser factory are highly prized by collectors. They are fine examples of the Art Nouveau style, which places its emphasis on naturalistic forms.
In the United States, another chemist and glassmaker, Frederick Carder, co founder of Steuben Glass Works in Corning New York, invented a illiant red glass by incorporating cadmium selenide and zinc sulphide in the mixture. Cadmium sulphide glass, which is yellow, changes to orange when selenium is added and to ight ruby red when sufficient selenium is added. Carder worked at Steuben from 1903-1932. The Great Depression curtailed the production of colored glassware and the more specialized lines of what is termed art glass.In the United States, another chemist and glassmaker, Frederick Carder, co founder of Steuben Glass Works in Corning New York, invented a illiant red glass by incorporating cadmium selenide and zinc sulphide in the mixture. Cadmium sulphide glass, which is yellow, changes to orange when selenium is added and to ight ruby red when sufficient selenium is added. Carder worked at Steuben from 1903-1932. The Great Depression curtailed the production of colored glassware and the more specialized lines of what is termed art glass.
But there is another kind of ruby glass that is not as costly to produce. Pattern glass, poured into molds, was mass produced during the 19th and 20th centuries. A number of companies made ruby pattern glass. The Northeast was the area of the United States where most glass was made during the mid 1800's during the height of its popularity. There was considerable concentration within the state of Pennsylvania; with Atterbury & Company, Chalinor, Hogan & Co. and Ripley and Company all located in Pittsburgh. Nearby were S. McKee & Co., McKee and Brothers, Fort Pitt Glass Works, and Bakewell, Pears and Company.
Anchor Hocking, based in Ohio, made glassware for everyday use. Their business made it through the 1930's Depression era and in 1938 they introduced Royal Ruby glass which they patented and made until 1967. (Between 1973 and 1977 several of the Royal Ruby patterns were manufactured again for a limited time)
Most Royal Ruby glass made by Anchor Hocking was not marked or signed, except with a factory sticker identifying the Royal Ruby color. When items were marked, the mark is an anchor with the letter H over the middle.
Other American glass companies that made their own version of red glass include Fenton, Westmoreland, and the Imperial Glass Company.
Whether you look for the hand blown examples of ruby glass or its less expensive molded versions, a display or a gift of red glass is a fine way to cele ate Valentine's Day on Fe uary 14th.
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