The Heuneburg pottery has been manufactured by means of marls containing varying amounts of lime. The temperatures of firing were low, ranging probably from only 500 to 600° C. The techniques used in the production of the ceramic decoration are investigated throroughly. It is shown, that the potters of the Heuneburg did not know how to make black Glanzton layers by means of firing iron rich clays in a reducing atmosphere. Instead of this, they used carbon as a black pigment. Carbon has been deposited on the clay body in a smoky fire (black polished ware) or it has been used in the form of soot as painting material (Alb Salem type ware). The application of soot paints in combination with iron oxide red was not very successfuly because the carbon black was burned during the oxidizing firing. But by using graphite as black pigment, potters succeeded in a very impressive dichromic painting since graphite resists an oxidizing atmosphere at moderate temperature. In the black polished ware carbon is enriched in the surface layer, but it has not been transformed into graphite. It is shown that the gloss of the surface is caused by mica.