The surface of ancient terra sigillata vessels did not require this burnishing or polishing.
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The oldest use for the term terra sigillata was for a medicinal clay from the island of Lemnos.
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Terra sigillata is usually brushed or sprayed in thin layers onto dry or almost dry unfired ware.
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Red gloss terra sigillata ware with relief decoration.
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Burnishing was a technique used on some wares in the Roman period, but terra sigillata was not one of them.
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Terra sigillata is also used as a brushable decorative colourant medium in higher temperature glazed ceramic techniques.
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Siphoning off the topmost layers of slip, which contain the smallest and lightest clay particles, produces terra sigillata.
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Reliefs can be impressed by stamps onto clay, or the clay pressed into a mould bearing the design, as was usual with the mass-produced terra sigillata of Ancient Roman pottery.
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Terra sigillata hispanica developed its own distinctive forms and designs, and continued in production into the late Roman period, the 4th and 5th centuries AD.