The Sao fired their ceramics in kilns of which numerous traces have been found. These ceramics were not hollowed out, but made from a solid support on which the artist laid out, in intaglio or in relief, the different facial features.

The clay that was used and the firing conditions show a great diversity and are quite variable in quality. One finds neither the systematic holes nor the mica or quartz spangles characteristic of the extraordinary Nok culture.