Sandwich gold-glass bowl
Hellenistic, about 270-200
BC
Found in a tomb at Canosa, Puglia, southern
Italy
A technical masterpiece, of mysterious
origin
This bowl of sandwich gold-glass shows a fine
floral design in gold leaf sandwiched between two layers of
colourless (clear)
glass.
In order to fit
together, the inner and outer bowls had to be made to an exact and
predetermined shape and size. They were made by a hot process,
which included slumping the glass into or over a ceramic
hemispherical mould or form. This was rotated while a tool was used
to work the soft glass downward. After cooling, the surfaces were
then cold-worked. The gold foil decoration was stuck to the outer
wall of the inner bowl, using an adhesive such as gum arabic mixed
with water. Finally, the two glass bowls were fused together by
placing the outer bowl into its original form (or a new one, if a
positive form was initially used), before carefully lowering the
inner bowl into it. The bowls were then heated together gradually
in a kiln. At a certain temperature the glass softened slightly and
the bowls fused together, though this did not happen uniformly
throughout.
A number of
these remarkable sandwich gold glass bowls are known. This one, and
three others, come from southern Italy, while others are known from
the island of Rhodes, Gordion (modern Turkey) and Olbia on the
Black Sea. One fragmentary example is decorated with a scene that
suggests an Egyptian origin, but scenes of the River Nile were a
popular theme in many parts of the ancient world. At this time many
luxury goods were traded in all of these locations, and we have no
clue as to where the sandwich gold glass was made. Their origin
remains a mystery.
H. Tait (ed.), Five thousand years of glass-1, 2nd paperback edition (London, The British Museum Press, 1999)
V. Tatton-Brown and W. Gudenrath, Catalogue of Greek and Roman g (London, The British Museum Press, forthcoming)
D.B. Harden and others, The British Museum: masterpiec (London, 1968)
L. Burn, The British Museum book of Gre (London, The British Museum Press, 1991)