IR and Raman spectroscopies, a way to understand how the Roman window glasses were made?

Two processes are known to make panes in West Europe during the Roman period: they may be cast on a flat surface or manufactured by the cylinder-blown process. The aim of our research is to give physico-chemical arguments to distinguish between both methods by using IR and Raman spectroscopies and to determine the fictive temperature Tf of the archaeological samples. The position of the 1050 cm−1 band in the IR reflection spectra of annealed samples versus Tf has been studied, giving a calibration curve to determine the Tf of the archaeological sample. Both, the position of the 1100 cm−1 Raman band and the ratio of the Q2/Q3 Raman bands intensities are also studied as a function of Tf for annealed samples. The Tf of both production methods is different. Our research favours the argument that the panes were produced by the cast method.