Artisan glass refers to handblown or individually created glass
items, as opposed to items such as standardized glass windows
and other mass-produced products. Until a few hundred years
ago, this description fit virtually all glass products.

Common glass contains about 70% amorphous silicon dioxide, the
same chemical composition as quartz and sand. Commercial glass
can be made of pure silica, but usually sodium carbonate (soda)
and calcium oxide (lime) are added. Various other additives are
also used, such as lead to give glass more "sparkle." Forms of
glass that do not include silica as a major component are
sometimes used for fiber optic cables and other specialized
technical applications.

Metals and metal oxides have long been used to give color to
glass. Brilliantly colored cobalt blue glassware is a
collectors' item. Glass can also be colored with minerals
including iron oxide (brown), chromium (green) , manganese
(purple), selenium (pink or red), or combinations thereof. The
method of heating and cooling the glass during its processing
can significantly affect the colors produced by these
compounds, in a process whose chemistry is complex and poorly
understood.

Lightning strikes which fuse sand can leave glass trails
resembling tree roots along the path of the electrical
discharge. Another naturally occurring glass, obsidian, has
been used by humans since the stone age. The Phoenicians used
glass as pottery glaze in 3000 BC, and glass beads, seals and
architectural decorations found in Mesopotamia date back to
2500BC. The first glass was created by melting sand, producing
a greenish product due to the naturally-occurring iron oxide in
the sand. Even today, commercial glass has a slight green or
blue tint, due to the presence of these same impurities.
Egyptians made glass beads and glass bottles dating to 1500 BC.
By 500 BC, glass-making technology had spread to Greece, and by
100 BC there were many glass-making centers around the
Mediterranean. Window glass was quite commonly used in the area
by 100 BC, such as thick, translucent samples found in Karanis,
Egypt.

The expansion of the Roman empire and widespread trade brought
glass-making technology to Europe, the British Isles and China.
After the fall of the Roman empire, their advanced glass-making
technology fell out of use, and glass production declined until
the seventh century, when Europeans once more began to revive
the use of glass for a variety of purposes. The beautiful
stained-glass windows on European cathedrals did not begin to
be made until the 12th century.

Venice developed into a glass-making center in the 14th
century, and the city became the hub of a lucrative export
trade in dinner ware, mirrors, beads, and other luxury items.
Venetian glass was of unusually high quality because the local
quartz stones used in its production were almost pure silica.
These stones were ground into a fine clear sand which was
blended with another locally occurring product called "Levant
soda ash", for which the Venetians held the sole monopoly. Even
today, multicolored handmade glass beads are called "Venetian
glass."

The Crown glass process of glass pane production was used up to
the mid-1800s. A glassblower would spin around 9 pounds of
molten glass at the end of a rod until it flattened into a disk
approximately 5 feet in diameter, which was then cut into panes.
Before float glass was invented, sheet glass was never
completely uniform, and in historical buildings, some of these
panes of slightly wavy glass can still be seen. In antique
shops, it is still possible to find old apothecary bottles,
each a slightly different size, produced by glass blowers.

Around 1688, glass casting was introduced, leading glass to
become a common, widely used material. The invention of the
glass pressing machine in 1827 allowed the mass production of
inexpensive glass articles. Handmade, irregular items are now
strictly the purview of artists.

About The Author: Frank Vanderlugt is interested in artisan
glass history.