The most far-reaching innovation in the manufacture
of glass in antiquity was the invention of blowing. On
the basis of the evidence of Prof. Avigad's excavations
of a glass workshop in the Jewish quarter in
Jerusalem, the invention of glass-blowing can now be
dated to the early decades of the first century BCE.
This discovery is of major importance for the history
of the glass industry, since it has proved to be the
earliest known instance of molded vessels found
together with vessels manufactured by the glass-
blowing technique.
The method of blowing a glass vessel has not altered
since glass-blowing was invented. The method used,
although it demands the greatest skill and dexterity,
is, in essence simple. The worker first gathers from a
crucible in the furnace a gob of molten glass on an
iron tube about 3-5 feet long, called the blowpipe (fig.
1). For the banded variety, the early glassmakers must
have first fused together monochrome canes of
different colors. After slightly inflating the gob, the
glass maker manipulates it into the shape he wishes by
swinging it, rolling or by 'marvering' it on a flat
surface. The gob or bubble is then further inflated
(fig. 2), shaped and cooled, often in an open, cup-
shaped mold, inflated further, and shaped by wooden
paddles or pincers or cut with tools until the desired
shape is achieved. Throughout the process the vessel
is rotated to prevent sagging and reheated when
necessary. For further finishing of its neck, handles
and rim as well as decorating the vessel, it is knocked
off the blowpipe (fig. 3). In order to do so, its
underside may be attached with hot glass to the end of
a solid metal pontil rod (fig. 4). The vessel is then
broken off the pontil (fig. 5), leaving a pontil scar and
the finished vessel (fig. 6), no longer viscous, but still
very hot, is placed in an annealing oven to be cooled
very gradually.
