Glassmaking Techniques in Antiquity

Although the chemistry of glass changed very little, since man started producing glass in Messopotamia, the techniques changed very much.

Glass is by definition an amorphous solid material made by fusing silica (sand component) soda (natron) and lime in a furnace heated to a high temperature (over 1150 degrees centigrade) Primary glass was usually produced where the raw materials and fuel were readily available, at a distance from the inhibited area. Glass is called amorphous because is neither a solid nor a liquid but exists in a vitreous or glassy state.

Glass was formed in nature when lightening stroke sand dunes or when volcanoes spew lava those natural glass pieces were used by early civilizations as spearheads and cutting tools as well as for decorative purposes

Many of the earliest glass vessels, dating to about 2500B.C. were core formed or cast glass in Egypt an Messopotamia they produced the early vessels by forming a core of ceramic- like material around a a metal rod and then encasing it in molten glass.

Flasks for scented oils were made this way. Another early technique involved different molds into which they were pouring hot molten glass

Another step in the same direction was creating mosaic glass .Like stone mosaic, mosaic glass is made up of a number of small pieces fused together.

Mosaic glass vessels are among the most colorful types of ancient containers.

As the demand for glass vessel increased, sophisticated production methods evolved and new forms were introduced.

In the mid-1rst century B.C. glassmakers around Jerusalem discovered that molten glass could be inflated into a bubble at the end of a hollow tube.

The blowing technique revolutionized the glass industry. The characteristic transparency,delicacy,and subtle colors,as well as many of the forms wineglasses, bottles, juglets, and jars that were introduced in the Roman period,as a result of the blowing technique, are still the trademarks of glassware today.

Glassblowing

The glassblowing developed in the Syro-Palestinian region in the early first century B.C. arrived toRome with craftsmen and slaves after the areas annexation to the Roman Empire in 64B.C. .As blowing allowed versatility and speed of manufacture it spurred a rapid evolution of style and form. How ever, although blown glass came to dominate Roman glass production, it did not altogether supplant cast glass.

Glass was made to imitate semi- precious stones like emerald, rock crystal sapphire, garnet,sardonyx ,amethyst and camelian.

Glass windowpanes were first made in the Roman Empire little if any attention was paid to transparency or even thickness because it was intended to provide insulation and security, rather than illumination or a way viewing the outside world, so they could be cast or blown.

Glass in modern life

Beyond every household uses could you imagine modern life without the scientific instruments microscopes, thermometers, telescopes, barometers, vacuum flasks and many others? Scientific fields like histology,pathology,bacteriology, molecular biology,astronomy could not have existed at all.

Where would have medicine without Pasteur and Koch being able to visualize microorganisms? Chemistry depends on glass instrumentation Agriculture greenhouses, improved the cultivation of fruit and vegetables.

Distribution of food and beverages by the production of glass bottles.

Navigation improved by the invention of the chronometer, lighthouses which could not have been without storm- proof lanterns and transparency of glass

Glass In Jewelry Manufacturing

The most common technique use for creating glass jewelry is fusing. Most contemporary methods of fusing involves stacking which is layering thin sheets of glass often different colors to create a pattern.

Fusing is the process of rounding or melting the batch inside the kiln (which is almost always electric but can be heated by gas or wood as in ancient times) the height of the temperature affects the result and the uses of of the fussed glass. The longer the kiln is held at maximum temperature the more thoroughly the stack will fuse.

Plates of dichroic glass (multiple ultra thin layers of different metals are applied to the surface of glass,kiln fired at extreme temperature,developed by NASA for use in face shields in space suits) can be fused with other glass in multiple stages of firing.

Due to variation in the firing process ,each piece of fused dichroic glass is unique ,so is the price.