Identification recovery and improvement of ancient Mediterranean ceramic manufacturing technologies for the reproduction of ceramic artefacts of archaeological value

In order to develop knowledge on the ancient technologies employed in the production of ceramics in Mediterranean countries, numerous ceramic sherds were collected from various ancient Mediterranean production centres and were analysed by physicochemical techniques including XRF and SEM-EDX. Complementary analyses were performed by collaborating partners using spectroscopic techniques like FTIR, NIR, Raman and XRD (P1, P4, P6). The databases include analysis results from 224 Majolica ceramic sherds from the main production centres of the Iberian Peninsula and Morocco (mainly workshops in Fez, Rtab and Lfilali), 73 Terra Sigillata sherds from production centres in Catalonia, 17 Iznik type sherds from Turkey (P3), 60 samples of raw materials and numerous Attic sherds from Greece, as well as a large collection of clays from sites Ayn at-Tina, ar-Rajif and Wadi Araba, Jordan, and sherds and full Nabataean pieces from various excavations in Petra, Jordan.

In collaboration with traditional potters, vase painters and other artists or artisans (ceramists) we have succeeded to establish a pool of skills which now allow us to reproduce various types of ancient Mediterranean unglazed ceramic ware (Greek-all periods, Roman, Nabataean). These artisans who were oriented to the taste of the tourist market were initially rather unwilling to focus on the demands for the reproduction of a high quality object. However, through visits to archaeological Museums, close examination of archaeological findings, contact with THETIS S+T personnel (seminars, analysis of archaeological artifacts), and contacts with archaeologists and actual archaeological findings, they improved the quality of reproduced artifacts. A series of new objects inspired from the every day life of classical Athens such as ceramic toys (dolls, marbles, spinning tops etc), oil lamps, bowls, plates were developed. In the course of our collaboration with the Greek Ministry of Culture (archaeological ephorates of Athens, Corinth and Thebes), the Benaki Museum, the Museum of Cycladic Art (the N.P. Goulandris Collection) and the Getty Museum in the USA, we were given the opportunity to create a large collection of artifacts from ancient Athens, Corinth and Boeotia as well as Roman Terra Sigillata and Nabataean ware. In Petra, Jordan, P4 was able to conduct laboratory scale reproductions with clays from Ayn Al Tinah and to transfer know-how to the workshop of the Taybeh Girls, which was producing replicas of poor quality. Their work now has improved tremendously thanks to the CERAMED project.

Documentation of failures and long term monitoring of production yield for selected vase types, i.e lekythos, kantharos, skyphos, kylix, hydria as well as Terra Sigillata and Nabataean, was combined with physicochemical and mechanical understanding of failures and with experience gained by artisans. This allowed a significant improvement of production yield and reduced the cost. The production yield was re-evaluated several times during the project and showed an improvement by between 25% and 55% depending on ceramic type. Further efforts were made to reduce cost by exploring the use of spraying the paint slip and using rough stencil techniques to speed up slip application. Refinements of these techniques led to significant further reduction of labour time. This is particularly relevant in countries where labour represents the major component of the cost of production.

Spectroscopic tools and methodologies were applied to characterize raw and related materials, including clays and mineral pigments, as well as archaeological ceramic artefacts provided by CERAMED partners. These included Attic ceramics provided by P6, Terra Sigillata provided by P2, Nabataean provided by P4, Iznik and Canakale provided by P3 and Majoilica provided by P2 and P5. The main spectroscopic techniques used by NHRF (P1) were non destructive and relied on NIR, MIR, ATR, IR reflectance and FT Raman spectroscopy. The characterization was complemented by work of other partners using non-destructive XRF and SEM/EDX for chemical analysis and OM and powder XRD analysis for mineralogical characterization. Finally, CT scans were applied by P4 to study the construction methods for certain artefacts. Additional techniques used by P4 include SME, XRD, XRF, FTIR, Raman and Atomic Absorption. P4 also conducted several firing experiments and mined several natural pigments from Petra, Jordan, and tested them as received or after appropriate treatments. All these products were also subjected to some of the spectroscopic techniques mentioned.

In response to contemporary environmental and health concerns for the use of lead in ceramics, P3 developed and evaluated lead-safe and lead-free frit formulations suitable for glazing Iznik and Majolica ceramics. In this context, compositions of frits having no lead such as alkaline-, boron- and bismuth-substituted silicates and borates, as well as low melting lead-safe silicates were produced and their optical properties and interactions with the quartz-based substrates were assessed. Further studies aimed at optimizing their technical properties including hardness, leaching ability and thermal matches between the glaze slip and the ceramic body. In collaboration with P1, spectroscopic tools were developed for the evaluation of lead-safe and lead-free formulations as glazing materials by designing and implementing accelerated leaching experiments. These basic studies were followed by successful laboratory productions of glazed tiles and pottery in collaboration with potters in Iznik and Kutahya and students of Fine Arts from the Mimar Sinan University in Istanbul, Turkey.

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