In addition, the influence of oxygen, UV-radiation, harvest time, sex and freshness of the purple molluscs on the colour outcomes will be treated. After that, the results of a series of dye experiments with extracted hypobranchial glands from fresh molluscs of the same species using different vats, both modern and historical, are displayed. The paper first presents a historical overview from the 5th century BC to the 15th century AD of the use of the red dye found in Bolinus brandaris. At Monte Testaceo (‘shell mountain’) in Taranto, the heaps found behind the Alcantarine convent– which now locates the National Archaeological Museum – and consisting mainly of spiny dye-murices show the importance of purpura rubra Tarentina in antiquity. In ancient times, however, it belonged to one of the most important and lucrative branches of textile finishing: mountains of crushed shells in the settlements along the coasts of the Mediterranean Sea still mirror the industriousness of purple dyeworks. Finally, with the discovery of the synthetic purple dye mauveine in 1856, real mollusc purple largely lost its significance in dyeing fibres.

After the fall of Byzantium in 1453 and the import of more economical dyes from the New World, the decline of shellfish purple was sealed.

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