Amphorae were pottery containers used for bulk-commodity transport in the Roman Empire. They provide direct evidence for the inter-regional and long-distance movement of agricultural products in the Roman Empire. In general, a whitish skin produced by the deposition of calcite and NaCl in the clay, is often present on the outer surface of Roman amphorae produced in regions with salt-bearing clay or when made with salt water. We employ terahertz reflective imaging with sparse deconvolution for the stratigraphic characterization of Roman amphora sherds excavated from Southern Italy, Southern Spain, and Northern Africa. A skin with a thickness between ~30 and 40 µm was found on the exterior of the sherds.