استفاده از فناوری‌های نوین نمونه سازی در بازسازی بخش های مفقود سفالینه های باستان شناسی

Abstract
The pottery and ceramic objects have an important role in the archaeology and Archaeometry they are the principal alphabet of archaeology in Iran and Middle East, because of the main chronological map in this area is based on the pottery, normally archaeologist finds potteries in their excavation from the Neolithic to the Islamic period and depends on the age of a site they may possibility access to the various kinds, hand-made pottery, unglazed and glazed pottery, etc. Despite the aesthetic values archaeologist use the historic pottery in such actions like dating of the site, recognizing the sources of raw materials, as well as the identification of past technologies (methods of making and decoration, estimate the oxidation or reduction atmospheres when pottery fired in the past, etc.)  On the other hand, many historical potteries are damaged and eventually destroyed by the three most important factors. 1) physical damage (Including: impact damage with mechanical forces and thermal shocks, wear and previous nonstandard reconstruction), 2) decay and superficial crust (Sedimentation and deposition of foreign materials from various sources resulting from the use of, dissolving and insoluble salts, residues during burial, spills of contact materials and absorption and etc.) 3) Chemical Deterioration (Including: Dissolution and exhaustion of the material from the process like: leaching, hydrolyze  and the chemical effect of biological colonization, finally due to the changing appearance and missing parts in the potteries. repair and restoration of damaged pottery works has a long history and the archaeologist believe that this practical work have a same history to create and making the first pottery objects, nevertheless reconstruction of missing parts have variety of method with different materials (such as the reconstruction of cracks and missing parts with gold leaf in far east countries) and different methods like (some rare restorations made by pottery fragments with the same designs and joining them in the original place). However, generally materials and methods for the reconstruction of ancient pottery have not changed much since about 80 years ago around the world and it based on the construction of the missing parts by reversible materials, such as plaster of Paris, in combination with other filler materials and art pigments.
Keywords: Pottery Objects, Archaeology, Reconstraction, 3D Scanner, 3D Printer.
 
Introduction & Method
Considering the remarkable progress made in the field of rapid modeling in the industry and the availability of new technologies today is a good platform for the introduction of such technologies in the field of archaeological studies as well as the conservation and restoration of cultural heritage. Such technologies, and indeed the most important ones, are scanners and three-dimensional printers. These technologies can be used to build a copy of objects and sculptures, relief and rock arts, valuable works and decorations in real dimensions (and / or with changing dimensions), as well as to reconstruct missing parts of destroyed works.
The main advantages of using these methods are:
• Reducing contact with sensitive objects and avoiding conventional and time-consuming commonly used contact and to some extent destructive, such as: molding, casting and filtration processes in the rebuilding of archaeological works
• More precision in the implementation of outstanding and complex designs than the traditional method,
• Achieving similar levels of quality to historical cultural effects using a combination of modeling techniques.
•  Construction of parts in different dimensions with asymmetric geometric models, so that there is little constraint on the form and geometric shape for construction.
• Ability to evaluate and modify the 3D layout and repeat it in case of dissatisfaction with each section in the shortest possible time.
• The risk of connection to the reconstructed piece is due to the neutral properties
• Reducing the time in making missing parts
 
Identified Traces
New technology in many cases led to better understanding of ancient archeology objects and also less-destructive methods in conservation, in recent years the rapid prototyping technique (RPT) was increasingly implemented in Engineering, Medical, and Industrial Design and Architecture fields. In this study RPT- including 3D scanning and 3D printing was investigated and implemented in reconstruction of missing part of ancient pottery objects.
The purpose of this research is to use modern prototype technologies such as: 3D scanners and printers for the reconstruction of the missing parts of the pottery works and the feasibility of using the above methods for the restoration of other archaeological objects, According to the purpose of this study a gray ancient pottery was selected from the prehistoric layer of Kul Tepe (Kul Tapeh) of Hadishahr that is an ancient archaeological site in the Jolfa County of Iran, this site in chronological point of view is dated from Late Neolithic/Early Chalcolithic till Achaemenid periods.
The pottery was a bowl with 20% missing part Includes 2 almost big and small triangular pieces. The reconstruction of a pottery work with missing parts of new technology of RPT was considered as this study’s subject. The ordinary methods for reconstructions of missing area in historical objects are molding and casting away from the object gap-filling with plaster and other additive materials, but in this new work the subject was scanned with an optical 3D scanner, it itself and its missing part was simulated in a 3D modeling software and then it was printed by a 3D printer. Finally, with some hand finishing work the new pieces attached to the historic pottery, the whole process was performed with minimum need to make physical contact with the subject, its potential in obtaining less-destructive reconstruction procedure was investigated and its advantages and limitations in comparison to traditional methods were identified. The results shows, implementing RPT in reconstruction of missing part of pottery works can lead to better understanding of ancient archeology objects and none or less-destructive treatment in working with ancient pottery masterpieces.
 
Conclusion
The reconstruction process can be achieved in very short time and higher accuracy. The printed piece can be an exact match of the masterwork. Several pieces of the missing part or the whole subject can be printed. Soft copy of the subject would be available for future works and can be used in other research centers. The subject can be reprinted with any desired changes in the pottery work original design. Temporary attachment of the printed piece to the masterpiece with preserving the potential of reversibility in the conservation of the object is achieved. The study was subject to the following limitations though: mono color printing of the missing piece, using a polymer as printing material, limited transparency in printing filaments and minor errors in the performance of the 3D scanner itself. As the content of the research goes, with the superiority of the advantages of these methods, we are faced with their disadvantages. And in general it can be said that the process undertaken is acceptable and can be used in the reconstruction of the cultural heritage and in particular the archeological pottery. Whereas the above methods, with the least effective interference, harmless interference, maximum compatibility with the host’s effect on the neutrality of matter and the preservation of the aesthetic aspects of the effect, can lead to a greater understanding of the work for the audience and researchers.