The history of glass

It is reported that glass was invented by ancient-Egyptian before 3500 years BC. The Egyptians used a method called core-forming. A shaped core was made of clay and dung, then molten glass was wrapped around it and shaped by rolling it on a smooth surface. The Egyptians made glass into jewelries and minisize glass bottles.

 

Around the end of 1^st century BC, a new method, glass blowing revolutionized glass production. This art was probably discoverved along the Eastern Mediterranean coast, probably in Syria. By blowing through a hollow tuben the experienced glassblower can quickly produce intricate and symmetrical shapes out of the “ gather” of molten glass at the end of his tube / rod. He can blow the molten glass into a mould. The Egyptian had known the technique of glass blowning and made a variety blown glass articles about BC 1000 years.

 

After ancient Egypt was defeated by ancient Rome, the prisoners was exiled to Venice to make glass professionally. Since then the technique of making glass came to Italy, because the effort of the glass makers, glass making was flourishing in a time in Venice. The Venetian provided the link between the ancient and modern glass making arts. Venetian glass was noted for its brilliance and for its light, imaginative forms. As the development of the Roman Empire increased, the art of glass making spread to many countries.

 

In 1676, an Englishman named George Ravenscroft, searching for a way to improve the luster and clarify of his glassware. He found that by adding lead oxide to his molten misture mixture, he could not only improve the clarify ( crystal clear ) of the glass,but also dramatically increase the weight, the index of refraction and the ability to cut the material without fracturing. This new glass became known as lead crystal and very quickly became the perfect medium for glass-cutters and engravers. Over past 300 years, their skills, proudly passed from generation to generation, have given lead crystal its world famaous repution.

 

The main difference between glass and crystal is the lead content. Glass is composed of sodium and potassium. Crystal is also composed of sodium, but in addition, it contains silicone, and has a lead content of 10-24%. The lead makes the glass heavier and, most importantly, the lead changes the refraction index of the item, which makes it appear brighter and cleaner. Because the refraction index is higher and lead crystal is not as brittle as standard glass, it is possible to make deeper and more complicated cuts in crystal.