The History of Glass Making and Blowing - Part 2
By [http://EzineArticles.com/expert/Milena_MJ_Kim/926987]Milena MJ Kim
Continued from Part 1.
The Middle Ages
With the decline of the Roman Empire, many craftsmen abandoned their trade or stopped developing their skills. However, glass-making did not cease and continued to be developed in Venice, with boasted elaborate guild systems. Glass sheets were produced for the first time in the Middle Ages, and stained glass windows appeared in public buildings and homes.
The Crusades also played a crucial role; the conquest of Constantinople in 1204 opened up trade routes through the Eastern Islamic territories, and extensive cultural exchange occurred.
Especially, the famous Venetian island of Murano was the center of another period of advancement in glass-making in the 14th century. Murano is a group of islands to the North of Venice and became the first world leader in glass manufacturing. Venetian Murano glass was special because local pebbles were made of almost pure silica and were ground into fine sand and combined with soda ash to produce high quality glass. Venetians held a monopoly in producing this superior form of cristallo glass (nearly transparent glass that can be blown into almost any shape), and with it made bowls, vases, and other types of glassware.
Venetians were also renowned in trade and supplied their craftsmen with proper material and know-how from other parts of the world; Venice interacted with Islamic states to share glass-making methods and styles, and even had a protectionist rule against imported foreign glass.
There is a famous story related to this protectionism. It is said that at first the city centered glass-making on the island of Murano instead of mainland Venice because it feared that fire from the foundries might burn down the city's wood buildings. However, some sources state that one of the main reasons for moving the industry to the island was that the city could ensure that no glass-making skills or secrets were exported. Thus, while glass makers were prominent citizens of Venice, they were restricted in their freedom to move out of the Republic. They were virtual imprisoners, and there were rumors whether the excuse about the fire and moving all the foundries to the island were true. Nevertheless, in this way, glassblowing remained a lucrative monopoly trade for Venice. Many glass pieces in this period were still luxury items, although some useful application of glass was seen in mirrors.
A lot of different countries imitated Venetian style. For example, in 1674, George Ravenscroft introduced a new type of glass, called lead glass or lead crystal. Lead glass was at first a substitute for the Venetian glass produced in Murano, and had some drawbacks because it developed crizzling (deterioration through cracks) within 1-2 years. Ravenscroft worked to fix this drawback, and this finished version of lead glass used higher proportions of lead oxide instead of potash. This new type of glass was ideal for optical instruments and was suitable for deep cutting and engraving, while Venetian cristallo was too fragile for such decorations. Some pieces with the original Ravenscroft seal still exist today, while some of them have crizzled.
The History goes on in Part 3.
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Article Source: [http://EzineArticles.com/?The-History-of-Glass-Making-and-Blowing---Part-2&id=5977679] The History of Glass Making and Blowing - Part 2