The Baetican workshops: a starting point to study Terra Sigillata Hispanica

Terra Sigillata Hispanica (TSH) was a Roman pottery easily recognized by its characteristic intense red color. It was produced in several workshops in the Iberian Peninsula. Seven of them were placed within the Baetica province. Here, we report a full characterization of a series of 35 TSH samples from the known Baetican centers. Additionally, two samples recovered from Caserio Silverio Mayorga (Antequera, Malaga), a possible eighth production center, and another sample with an unpublished stamp (reading 'NOMO') are also studied. The main employed techniques were stereomicroscopic examination, elemental analysis by WDXRF, Rietveld quantitative phase analysis from laboratory XRPD, including amorphous quantification by the innovative G-factor approach and, finally, SEM-EDX for paste-microstructure and slip characterization. The results rule out Caserio Silverio Mayorga as a TSH production center. The stamped sample is not related to Alameda TSH, and it is likely from La Rioja. Chemical data analysis allows workshop separation when used with macroscopic examination. The mineralogical data show a wide range of variation in amorphous content (24-68 wt%), and also allow firing temperature estimation (900-1000 °C). The SEM-EDX study highlights the markedly thicker slips of Andujar productions (20-40 μm), made with c. 0.1 μm particles, compared to the rest of the workshops (≈10 μm).