THE USE OF TYRIAN PURPLE IN THE WALL PAINTINGS OF THERA

• S. Sotiropoulou, K. Andrikopoulos ("Ormylia" Art Diagnosis Center, Sacred Convent of the Annunciation, 630 71 Ormylia, Chalkidiki, Greece)
• E. Chryssikopoulou (Excavation of Akrotiri)

Tyrian purple, one of the most prestigious and well-known natural dyes throughout its historically documented use, has always been famed both for its exquisite colour which acquired symbolic attributes and the specialised knowledge required in its production, raising its price over time.

The use of Tyrian purple as a textile dye in the Aegean world has been at least indirectly proven: significant quantities of shells found in several settlements on Crete, on Kythera and other insular and continental sites, as well as tablets in Linear B provide evidence for the collection, treatment and preparation of the purple dye. Its use in the wall paintings is now attested thanks to the findings in Akrotiri, namely the purple paint details in the compositions of Xeste 3 and a powder in the form of a small ball found in the building Bronos 2.

In the samples taken from the paint details, Tyrian purple has been identified through the use of Raman spectroscopy. Raman spectra have been also acquired from a sample of the purple powder confirming the presence of Tyrian purple and verifying the initial indications extracted from earlier results of X-Ray diffraction and X-Ray fluorescence analyses.

The sparse use of Tyrian purple in a very few compositions belonging to one single room is not unexpected from the technical point of view, taking into consideration the incompatibility of this organic pigment with the fresco painting technique. Moreover, it is obviously related to the painting conventions of the time, the symbolism of the precise compositions (collection of croci, procession of women, rituals) and the religious character of this building (Xeste 3 is a public building with evident religious character).

The identification of Tyrian purple in the palette of the Theran painter prompts a further study responding to both pure archaeological issues of dating, provenance and technology of preparation of the pigment and archaeometrical issues related to the exact chemical composition and the technique of application in the wall paintings.

Up to now it was believed that the palette of the notable local wall-painting workshop of Akrotiri consisted exclusively of mineral pigments. The results of this study reveal the existence of a second synthetic pigment apart from Egyptian blue resulting also from a laborious manufacturing process. The fact that this second synthetic pigment is organic refocuses interest on the investigation of the painting technique and directs the research towards the detection of any binding medium that was possibly used in the application of the surface paint layers on dry ground.

Thanks to these new results considered in comparison with the archaeological context and the dating of the artefacts from the East, the issue of the origin of the precious colouring material as well as the question of the locality of the pioneer centre of Tyrian purple production (in the East Mediterranean coastal centres or in the Aegean world) are reintroduced.