The Chemical Basis of Ancient Greek Vase Painting

In classical times, black‐ and red‐figured vases were an important Greek export article, balancing payments resulting from grain import. This was especially true in Athens. The red pigment was always Fe2O3, and the black Fe3O4. A carefully chosen clay containing iron, which could be formed by hand with a simple potter's wheel, was used for thr vessel. The fired ceramic usually provided the red of the vessels. For the black painting, and for the occasionally used red painting (Intentional Red), a layer of finely elutriated clay was painted on. The vessel was fired between 800 and 900 °C, first under oxidizing conditions, then under reducing, and finally again under oxidizing conditions. From the reproductions of Adam Winter it may be concluded that an illitic clay was used for the black figure painting. During the reductive firing, the painted layer became impervious by sintering owing to the K2O content of the clay. A kaolinitic clay, poorer in K2O, served for the red painting. This clay remained porous on reduction and was reoxidized, like the ceramic of the vessel, in the second oxidation. For the terra sigillata of the Romans, the entire surface of the vessel was covered with a clay slip, which on firing under oxidizing conditions at higher temperatures, gave a hard surface, so that the vessel; could be used as table utensils.