The two kilns studied are typologically and structurally different
to one another. One (Structure 6) is a true pottery kiln, built with
unfired bricks in a trench dug in the Ca-poor and -rich clayey lacustrine
deposits. Roman potters used only the former as raw material
for the bricks and the binder. This technological choice was likely motivated
by the fact that such clays are better suited to withstand the
high temperatures occurring in fire chambers of pottery kilns than
the lower melting Ca-rich raw materials. The maximum temperatures
on the inner surface of the firebox are estimated between 1050 °C
and 1200 °C. This is consistent with the estimated ~1100 °C recorded
by pottery wasters found in a nearby kiln (zone Sur St. Martin, Jornet,
1982). Comparably high temperatures (above 1050 °C on the bottom
of the fire box) and the use of Ca-poor clays as raw materials for the
kiln were also reported by Maggetti (1995) for a Roman pottery kiln.
The shape of Structure 180 is very different from any known pottery
kiln structure. The inferred firing temperatures of its firebox are
lower (maximum between 950 °C and 1050 °C), although the walls
were poorly preserved and further thermal data of the firebox are
lacking. The shape and temperatures therefore fit best with a drying
oven.