Analysis of the Colors of the Antique Portrait Terracotta
In 2017 during underwater archaeological excavations of cultural heritage object. The “Ak-Burun bay” in the waters of the Kerch bay a large piece of portrait terracotta was found at the depth of 0.7 m under the sea bottom. The “Ak-Burun bay” is an accumulation of the damaged cultural layer with the area of more than 75 000 m2, which deposited in the harbor of the ancient Greek Panti capaeum city during VI cent. BC – XI cent. AD and displaced to Ak-Burun cape during dredging in 1970s. The displaced cultural layer predominantly consists of large pieces and whole ceramic vessels imported from various ancient Greek centers of the Mediterranean and Asia Minor.
The terracotta sculpture of a man’s head established in the proportions of an adult human. The clay composition and a high amount of pyroxenes testify its similarity to the product of Sinope.
Before the transfer of the find to the museum during the initial sediment removal several micro samples from the surface of the sculpture were selected and preserved such as two samples from the inner part including an exfoliated piece (S1) (Figure 1, Area 1) and a fragment of the dark gray stuck piece (S2) (Figure 1, Area 2), two pieces of the dark brown substance from the mustache (S3) (Figure 1, Area 3) and from the nostrils (S4) (Figure 1, Area 4), a red brown fragment from the upper lip (S5) (Figure 1, Area 5) as well as a sample from a pit in the beard (S6) (Figure 1, Area 6). The selected samples were of a tiny size, no more than 1 mm. Thus, the sampling didn’t cause any damage for the sculpture. The samples were delivered to the National Research Center ‘Kurchatov Institute’ for the further investigations.
The complex of the analytical techniques including optical and scanning electron microscopy (SEM) with the use of the energy dispersive X-ray microanalysis, Fourier transform infrared (FTIR) spectroscopy and synchrotron X-ray diffraction (XRD) was conducted.
The untreated samples were used for the XRD studies. After that they were polished to get micro sections for microscopic studies.
Firstly, microscopic studies were carried out in order to identify chemical composition and morphological structure of the samples. Figure 2 demonstrates optical images of the key samples and SEM images of their microsections. Energy dispersive X-ray analysis has shown that the material of S2 (Figure 1, Area 2) is lead. S2 could be a residual part of a mount placed in the inner part of the terracotta. Ancient Greeks and Romans often used lead for fixing sculptures, architectural details and stone blocks. Microphotographs (Figure 2) demonstrate that S3, S4 and S6 are of the same homogeneous structure with a smooth surface and roundish pores that might evidence heating of the materials in the past (Figure 2a, 2b and 2d). The morphology of S5 (Figure 2c) is different from the other samples, it consists of two red and white layers. SEM images of its surface demonstrate the needle structure.
As the main result of the comprehensive study it was found that the Antique ceramic sculpture of the man’s bearded head found in the Kerch bay has sandarac coated hair, beard and mustache. The mineral iron-manganese dye of dark brown color was attached onto the resin. The lips were colored with red ocher attached onto the gypsum surface. The gap between lips was filled with the same substance as the hair. The face and eye color remain unknown due to its elimination during the stay on the seabed. Terracotta had lead fasteners in its inner part. The terracotta could be used for a ship decoration due to the way of resin using, which is rather seldom. Thus, Pliny reminded about the tradition to cover walls with the resins by the inhabitants of the Ancient Carthage in order to protect them from the wind, rain and sea evaporations. The resin is actually the best protective substance from permanent action of the sea salt and humidity for a vessel and the whole its rigging from marine ropes to a wooden trim. Therefore, such unusual way of decoration could be a natural tribute to maritime traditions. The usage of the heated resin could seriously enhance the adhesion and durability of the mineral pigment.
Arts and Social Sciences Journal