THE DECORATION OF THE "WHITE GROUND HYDRIAI HADRA" FROM THE RHODIAN POTTERS' WORKSHOP: A PRELIMINARY STUDY

• A. Giannikouri, Sister Daniilia (Historic and Archaelogical Institut of Rhodes, Hippoton Str., 851 00 Rhodes, Greece)
• K. Andrikopoulos, S. Sotiropoulou, Y. Chryssoulakis ("Ormylia" Art Diagnosis Center, Sacred Convent of the Annunciation, 630 71 Ormylia, Chalkidiki, Greece)
• Y. Chryssoulakis (National Technical University of Athens, Department of Chemical Engineering, Iroon Polytechniou 9, 157 80 Zografou Campus, Athens, Greece)

The term "Hadra hydriai" is used for two closely related types of vases - the clay ground Hadra hydriai and the white ground Hadra hydriai. A great number of both types of vases were found at the Hellenistic Hadra cemetery in Alexandria. They were used as cinerary urns in for the burial of mercenaries, consuls and other officers who died in the court of the Ptolemies. Hydriai of this type were also found as well in other necropoleis apart from Egypt.

Continuous archeological research in Rhodes' necropolis unearthed a great number of white ground Hadra hydriai. Their study proved that a prominent workshop existed in Rhodes in the period from the beginnings of 3rd to the middle of the 2nd century B.C. The trails of this workshop in the mentioned time period we attempt to investigate.

The most remarkable feature on this type of hydriai is their colourful decoration. The hydria's surface is usually covered with a white or yellow layer, upon which various representations are painted, sometimes simple and occasionally elaborated with plant or flower decorations wreathed with garlands.

In this joint work we will report the results as well as the preliminary observations that became evident after a thorough study of the colour palette and the technique used by the Rhodian craftsmen to apply on the painted decoration. An efficient number (85) of micro- samples that were carefully taken from the painted surface of 44 representative hydriai with characteristic decoration, covering the whole time period of the referred category, were studied in order to derive significant preliminary conclusions.

The methodology that was followed included optical microscopy and mRaman spectroscopy for the study of cross sections' stratigraphy in properly embedded samples, as well as mFTIR spectroscopy. Moreover, in order to confirm and extend the spectroscopic results, other analytical techniques were applied as well in a number of selected samples: Elemental microanalysis by using Scanning Electron Microscopy, X-Ray Diffraction and High Performance Liquid Chromatography.

The experimental results indicated the chemical composition and structure of the preparation and the paint layers. The colour palette comprises various pigments such as: Egyptian blue, Hematite, Cinnabar, red lake (Madder lake), Lead Arsenate yellow, Goethite, Calcite, Kaolinite, Lead white, Aragonite, Carbon black and Pyrolusite.

Many of the referred pigments are artificial (Egyptian blue, Madder lake, Lead white) and their synthesis requires specialised workshops and specific know how.

The selection of the materials and their distinct practice on the painted decoration of Hadra hydriai as investigated through this study, form the traits for identifying the Rhodian workshop. The comparative study of the results that are presented was done in order to ascertain the evolution of the technique and style of the local workshop during the whole period of its existence, as well as in order to investigate the elements that distinguish it from the similar workshops discovered in areas away from Rhodes.