a great variety of monogram crosses and plain crosses amongst the stamps. Gallery of Roman terra sigillata Modern pottery In contrast to the archaeological usage, in which the term terra sigillata refers to a whole class of pottery, in contemporary ceramic art, 'terra sigillata' describes only a watery refined slip used to facilitate the burnishing of raw clay surfaces to promote glossy surface effects in low fire techniques, including primitive and unglazed alternative western-style Raku firing. Terra sigillata is also used as a brushable decorative colourant medium in higher temperature glazed ceramic techniques. In 1906 the German potter Karl Fischer re-invented the method of making terra sigillata of Roman quality and obtained patent protection for this procedure at the Kaiserliche Patentamt in Berlin. Making modern terra sigillata Modern terra sigillata is made by allowing the clay particles to separate into layers by particle size. A deflocculant such as sodium silicate is often added to the watery clay/water slip mixture to facilitate separation of fine particle flocs or aggregates. For undisturbed deflocculated slip settling in a transparent container, these layers are usually visible within 24 hours. Siphoning off the topmost layers of slip, which contain the smallest clay particles, produces terra sigillata. The remaining larger clay-particle layers are discarded. Terra sigillata is usually brushed or sprayed in thin layers onto dry or almost dry unfired ware. The ware is then burnished with a soft cloth before the water in the terra sigillata soaks into the porous body or with a hard, smooth-surfaced object . The burnished ware is fired, often to a lower temperature than normal bisque temperature of approximately 900 °C. Higher firing temperatures tend to remove the burnished effect because the clay particles start to recrystallize. Reuse of Roman pottery Since the 18th century Samian ware pots have been found in sufficient numbers in the sea near Whitstable and Herne Bay that local people used them for cooking. See also Cimolian earth Notes References Boardman, John ed., The Oxford History of Classical Art, 1993, OUP, Brown, A.C. Catalogue of Italian Terra-Sigillata in the Ashmolean Museum, Oxford 1968 de la Bédoyère, G., Samian Ware, 1988, Chenet, G., La céramique gallo-romaine d'Argonne du IVe siècle et la terre sigillée décorée à la molette, Mâcon 1941 Déchelette, Joseph, Les vases céramiques ornés de la Gaule romaine, Paris 1904 Dragendorff, Hans, 'Ein Beitrag zur Geschichte der griechischen und römischen Keramik', Bonner Jahrbücher 96