German is a confusing language at times. Treibteller here is a cupellation
dish (from cupellation = Abtreiben). The point is to get a nice porous (=
absorbent) ceramic material sufficiently poor in silica to be chemically
refractory against the attack by liquid lead oxide / litharge. In later
times, bone ash was the material of choice; earlier, marly clay or even
crushed marine shells were used as in I. Keesmann's (1993) example from
Monte Romero. A mixture of crushed shells and grog (crushed ceramic
material) would probably give a good such cupellation hearth material.
One further aspect here is the shape of the 'Treibteller'. It can be a
proper dish in the sense of a free-standing open vessel, or just a lining of
a hearth in the ground. The difference is that for a dish you need material
with enough internal strength to keep it in shape during the firing, while
the hearth lining will have no such problems, kept by the surrounding soil.
To my opinion, there may well be a transition fro the hearth to the dish
somehwere around the Roman period; but too little research is published to
be certain about this.
Any more questions / comments welcome!
Thilo Rehren
Institute of Archaeology
University College London
31-34 Gordon Square
London WC1H 0PY
Great Britain
(44) 20 7679 4757
(44) 20 7383 2572 fax
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