Hello,
In the framework of a broader article on Hellenistic ceramics in Central Asia, I worked on grey-black paste ceramics in order to try to establish connections between Central Asia and the Mediterranean world. One of the objectives was to specify the chronology of their appearance but also to understand if there was a cultural link between this ceramic and the evolution of the colonization of Central Asia during the Seleucid and Greek-Bactrian period. This unpublished work could be an interesting field of work for those who have already had the opportunity to work on the subject in other parts of the Hellenized world. The question is whether this type of pottery corresponds to specific needs, to specific tastes for a particular population.
Thank you for your help.
JBHoual
Dear J-B., Working with clay/ceramics, I have encountered three ways pottery can turn grey/black.
1. Manganese containing clay or the addition of manganese to a sort of clay
2. Iron-bearing clay that during firing in a kiln under reducing conditions converts hematite (Fe3O4) into magnetite which is black (Fe2O3) or
3. A clay that was taken from the coast closeby a sea or ocean. Most of the Greek island clays are grey/black.
We were able to analyze the above points by using neutron activation analysis (INAA) in our lab at Jerusalem. Success.
Thank you for your answer.
Indeed, when a cooking is done in reduction, without oxygen, we obtain darker shades. This is particularly true for engobes. What troubles me is that you can have beige pasta with a black slip and black pasta with black slip. I have the impression that there are two different processes for the dough and for the slip. The slip may have a different composition. In addition, black pasta is harder, more vibrant than beige pasta. This is certainly due to different cooking temperatures. For the Black Sea, the presence of black paste ceramics is quite frequent. In the Persian Gulf there are also black pastes (much less frequent), but what makes it possible to produce a black ceramic, apart from the fact that it can be combined very well with tableware. In the Persian Gulf (Failaka), this ceramics is not of good quality so why choose this technique (clay quality at the beginning?). In Pakistan, in Banbhore on the banks of the Indus, we have a large production of Islamic ceramics, of very medium quality, with a black-grey fabric. At the same time, we have in northern Pakistan (Taxila) a ceramic very close to the black glazed ceramic (Northern Black Polish) but therefore the tradition is not maritime. So why use this technique: export of a material culture like the Macedonians to Central Asia (fashion phenomenon), functional because this clay is of very good quality, technological (presence of mineral elements near the sea). Analyses should indeed be carried out.
Your initial question was about the grey/black colors.
Now I heard a bit more, I would indeed suggest to take some samples of each clay and pottery and look with the means of Petrography to the mineral composition which is visible under the microscope. When this is unsatisfied, I would suggest EDXRF or PIXE or the more expensive INAA. Pay attention that any clay has still to be fired before taking a thin-section or a powder sample.
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