Abstracts - International Initiative for Georgian Cultural Studies

RESTORATION/CONSERVATION
Francesco Imperi
University Roma Tre. Italy
Understanding the Etiology of Rosy Discoloration on Ancient Wall Paintings: A Molecular
Approach
The inventory of microorganisms responsible for biological deterioration of ancient paintings has become
an integral part of restoration activities. Here, the microbial agent of rosy discoloration on medieval
frescoes in the Crypt of the Original Sin (Matera, Italy) was investigated by a combination of microscopic,
molecular and spectroscopic approaches. The bacterial community from three rosy-discolored painting sites
was characterized by 16S rRNA gene-based techniques. The eubacterial population was composed prevalently
of Actinobacteria, among which Rubrobacter radiotolerans-related bacteria accounted for 63–87% of
the 16S rRNA gene pool per sampled site. Archaea, with prevalence of Haloarchaea-related species, were
detected in one of the three sites where they accounted for < 0.1% of the total 16S rRNA gene pool. Raman
spectroscopy confirmed the identity between R. radiotolerans carotenoids (bacterioruberins) and pigments
responsible for color alteration of frescoes. This investigation provides the first evidence of a causal relationship
between heavy contamination by Rubrobacter-related bacterioruberin producing bacteria and rosy
discoloration of ancient wall paintings.
Nino Kitovani
Georgian National Museum. Georgia
The Information on the Study and Conservation Methodology of the Central Icon of the Ubisi
Triptych
The Ubisi icon of the Virgin (SEG#657, MM 225/a; 33X27 sm. Wood, canvas, gesso, gold, egg tempera,
repousse), an important example of 13 th century Georgian icon painting and metalwork, forms a part of the
treasury of Ubisi Monastery and represents the central icon of the triptych specially created for this monastery.
It was already damaged in 1925 when it was brought from Ubisi, together with other icons, to the Sh.
Amiranashvili Museum of Art, where it is still kept today.
Today, the icon remains in pieces. Its board has been split in two: the canvas with the painting and silver
plates with gilded repousse décor. At this time, we will discuss only the condition of the ground paint layer,
wood and canvas, and their methods of their study and conservation.
There has been complex damage wrought to the organic and non-organic materials of the work, which
make up its structural elements. Due to humidity and biological attacks present throughout the centuries,
the chemical alterations and loss of mechanical stability to the piece is obvious. The binding material has
disintegrated, the denseness of gesso (levkas) paint layer has decreased and the adhesiveness of the layers
has weakened. There are paint losses, especially in the parts under the repousse. The board has been damaged
by worms, powdered and fragmented; the canvas is fragile and fragmented as well. The glue used to
attach the paper to the paint layer has also disintegrated.
To determine the best methods of conservation and to better understand the technique and technology of
Georgian icon painting, it was necessary to undertake the complex investigation of contents of the remaining
parts. Only few cases of the systematic and interdisciplinary study of the icon painting technique exist.
Considering this, the complex study of Ubisi icons is especially important, as long as the authenticity of the
icon is not lost by the restoration/rehabilitation of the work.
We have used the following available microdestructural methods: A microbotanical analysis of board,
canvas and wax (performed by The Institute of Paleobiology); a microchemical analysis of the pigments
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