In order to produce a core-formed vessel, a
removable core of material, probably a combination
of clay, mud, sand, and an organic binder, is built up
around a metal rod into the shape of the interior
space of the desired vessel. This prefabricated core is
then covered with a glass powder or by trailing
threads of glass over the core as it is rotated. This
glass coating would be melted above a controlled fire
in order to transform it into a glassy layer around the
core. This process was then repeated several times in
order to build up the successive layers into the vessel’s
stable wall. To create the pattern on these vessels the
artisan attached the tip of a hot white glass cone to its
neck where it left an impressive blob. While rotating
the rod clockwise above a controlled fire, a thin thread
was pulled off the cone in a counterclockwise direction
around the body. The glass trails were finally dragged
upwards and downwards by means of a pointed tool
to create deep fluting and a wavy zigzag pattern. The
vessel, while still soft, could then be smoothed and the
decoration pressed into the surface of the vessel by
marvering, the rolling of the vessels on a flat surface,
usually stone. A thread was then fused to the edge of
the rim before strands of hot glass were pressed onto
the wall to shape one or more handles. When the
vessel with its design, foot, and handles was
completed, the rod is removed and the vessel
annealed. Finally, the craftsman scraped out the core
material.
Stages (slideshow)
1. The prefabricated core is covered by glass powder
and fired to form the body of the vessel
2. The decoration is made by winding a prefabricated
and softened glass cane around the body
3. A tool is drawn through the coils to form festoons
or other patterns
4. The out-splayed rim is made with a tool before it is
flattened by pincers
