engleski

Computer tomography as a non-destructive diagnostic method in the field of conservation- restauration

The Branch for conservation-restoration, Arts academy of Split started scanning artwork with MSCT 6 years ago. Purpose of the scans was determining the scope of destruction, errors in artwork structure and methodology of production. In early stages of MSCT scanning technology, artwork was scanned with X-ray too, for the comparison purposes. Using various software applications, scans obtained by MSCT equipment can be shown and analyzed as multi- planar reconstructions (MPR), “virtual endoscopy” 3D images of various structures and materials for different measuring purposes: length, area, absorption. Examples of application methods Wooden sculpture St. Ante Sculpture was scanned using X- ray first. This X-ray scan clearly shows multiple nails that were used for initial assembly and for later reconstructions as well. Joints of the wooden planks are visible, as well as “errors” in the core itself. Darker areas of the central part of the chest and lower end of the body have shown indication of cavities, however it is not possible to clearly identify interior structure of the object and layout of all wooden parts. Afterwards, the object was scanned with MSCT as well. Analyzing the lateral, side and axial MPR views resolved perplexities about technology of producing the sculpture. The central part of the structure was made from the wood that had its core removed. This way, two concave forms were made with reduced weight of the complete object. Final form was accomplished by laying down external wooden parts on top of the central part. Wooden parts were joined with glues and nails made of metal. The lower part of the structure is connected to the base with joint “pero-utor” and nails. Plank joints were filled with putty from the outside. Wooden crucifix It was noticed that the sculpture is very light. Soundings showed that the interior is mostly hollow and body was made of unusual spongy material. This material was identified as Ferula communis , a wild plant widespread across Mediteranean. The sculpture was scanned with MSCT. Scans showed it consists of interior shell which was made by laying down multiple layers of paper. The shell was later lined with round sticks of Ferula that were glued together. When enough thickness was obtained, the details of anatomy were derived. Afterwards the complete surface was lined with several layers of paper. Preparation layer and paint was applied over the paper. Scanning with MSCT equipment also enabled the virtual endoscopy which provided extremely detailed image of the interior. Fragment of the amphora’s neck Hard- core deposits of calcification on the surface of archaeological objects are causing great difficulty in diagnosing the condition of the surface layer and the structure of the objects. This kind of problem appeared during analysis of fragments of amphorae’s neck discovered during first underwater examination of the bay of Pharos. Fragment of amphora’s neck was covered with a hard crust of calcification. Under the calcification there was a sight of stamp of the workshop that had made this amphora. Given the scientific value and uniqueness of the finding and the fragility of the stamp, to avoid any damages a scan with MTSC was made that virtually eliminated plaque calcification. Beneath layers of calcification the scan showed letters “PLATO”, stamped in shallow relief. MSCT scan of amphorae’s neck enabled an insight into the internal structure of the object. There are clearly visible admixtures in clay, cracks within the walls of the container and material weaknesses created due to the method of the baking process.

computer tomography ; non-destructive diagnostic method ; conservation-restauration

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