Glass's History Is Unclear; Tankard Is Probably German in Origin but Is Difficult to Date. Combining Features from Different Periods Suggest It Was Made in the 19th Century
THIS is an intriguing piece of glassware found in a dealer's bargain bin at an antiques fair in Carmarthen. It's a footed tankard and cover, hand-blown and cut, and surprisingly light in weight: the first sign that it comes from continental Europe rather than being made of British lead glass.
Glass is basically made from melted silica obtained from sand, quartz or flint. A flux is added to the silica to lower the temperature needed to melt it and to improve the quality of the glass. Traditionally, the two main fluxes used are forms of potash and soda.
Potash was generally obtained by burning vegetation, particularly bracken, and was the preferred flux in Northern Europe where there were abundant forests.
This produced the early German Waldglas, or wood glass, which tended to have a green tint.
In the Mediterranean, soda glass was more common, the soda being obtained either from mineral deposits or from the glasswort plant, known as barilla in Spain where much of it came from.
The Venetians were the masters of soda glass, producing a fine clear version called cristallo. This was generally quite thin, however, so was only suitable for diamond point engraving, not cutting.
In the 17th century, while George Ravenscroft was experimenting with adding lead to glass in England, experiments were also being carried out elsewhere in Europe, leading to the development of a harder, shinier form of potash glass in Bohemia and some of the German states that was like rock crystal in appearance and which could be cut and polished on a lapidary wheel. …