The condition of the mosaic
The total area of preserved mosaics in hall A was about 11 square meters (out of a total of 214 sq. m. excavated in hall A). The mosaic had been fragmentarily preserved in poor condition, particularly in the north and south parts of the hall, while in the central part, the lower layer of the substrate of various-sized stones survived. The floor’s substrate had subsided due to its composition and the collapse of the upper part of the monument in antiquity. In the preserved sections, disintegration of the mortar which held the tesserae was noted due to its exposure to environmental conditions and loss of tesserae. Following approval of the study, the fragments were removed and transferred to the laboratory for conservation. Excavation to a depth of 4 meters below the mosaic floor was conducted to investigate building phases predating the palace.
Conservation & restoration of the mosaic
The following tasks were performed:
• Filling of the excavation trenches
After excavation was finished, the excavated trenches were filled with crushed gravel (maximum diameter of grains: 30 mm.), which compacted extremely well. The filling was done in layers (thickness: 15 cm.), and the compaction was done with a small hand-held vibrating compactor. The unexcavated surface was reclaimed with a layer of gravel (height of layer: 30 cm.), which was given the appropriate slopes for the runoff of rainwater.
• Construction of a drainage channel
To collect and remove rainwater, a channel running parallel to A. Svolou Street was constructed in the southern part of hall A, which directed the water to the old existing well through a shaft and pipe.
• Conservation and resetting of the tesserae in aluminum frames using compatible mortar
Conservation involved mechanical cleaning of the tesserae of deposits, the cleaning of mineral deposits using pulp paper pads and deionized water, filling in small destroyed sections (gaps) with tesserae, and grouting the joints.
• Resetting the tesserae at the ancient ground level and joining the individual frames with compatible mortar. The motifs were filled in by etching in the mortar.