Greece enjoys ample deposits of fine clay, in particular large quantities of good quality secondary clay. The clay beds around Athens are distinctive for their chemical composition, mainly with respect to their iron oxide (Fe2O3) and calcium oxide (CaO) contents, which are responsible for the reddish-orange colour of the fired clay. This marks it out from the clays of other regions such as Corinth where the pottery has a lighter, creamy-white appearance. Indeed spectroscopy and other methods has revealed unexpected connections amongst vases distributed around the Mediterranean basin, as in the case of the hydriai from Hadra near Alexandria. Previously thought to be Egyptian in origin analysis of their chemical composition has shown them to have been imported from a workshop in Rhodes[16].Primary clays were rarer and used sparingly mostly as an accessory colour in decoration, for example on white ground vases where kaolinite was applied in a thin uniform layer while the pot was on the wheel. All clay was purified through levigation in order to remove such impurities as quartz and limestone in order to increase the malleability of the clay in the potter’s hands.
http://en.wikipedia.org/wiki/Pottery_of_ancient_Greece
http://en.wikipedia.org/wiki/Pottery_of_ancient_Greece
