Stručni rad
Conservation-renovation interventions on ancient lamps
Anđelko Kovačević
; Arheološki muzej Osijek, Osijek, Hrvatska
Sažetak
CONSERVATION-RENOVATION INTERVENTIONS ON ANCIENT LAMPS
Conservation-renovation intervention on ancient lamps found during the preservation archaeological excavations in Osijek in Martin Divalt street, numbers 120 and 122 on the site of southern necropolis of Roman Mursa were carried out from 2008 until the beginning of 2010 in the preparation workshop of the Archaeological Museum in Osijek, that was established in 2008 and headed by senior museum preparator Anđelko Kovačević. Restored lamps were presented to the Croatian public within the exhibition OS-DIV-120- Roman necropolis from the time of Severus at the above mentioned museum. Among other items at the exhibition there were 13 restored i.e. 10 ancient lamps (three were not preserved and could not be completely restored since the number of fragments was insufficient for a definite reconstruction in relation to the following features: open or closed canal between the discus and lamp nozzle, eyes on lamp shoulder and their sequence, possible ornaments on the discus etc.). Firstly, it was necessary to establish the sort of the pottery material, the level and causes of possible damages and sort of impurity, technique and way of making. As a result of this it was noted that the lamp walls are unevenly thick, as well as the colour and quality of the making, which was to be expected since these are grave goods. Most lamps are approximately 2 cm high, 5 cm wide and 8 cm long. These are lamps with open canals with double or triple band thickening on a more or less unevenly shaped shoulder. The bottoms are flat and slightly concave, some lamps carry a craftsmans signature, some had a circle or round bulge and some carried no symbol at all. It is to be emphasized that these are by no way originals but the copies of the then workshops such as e.g. the Fortis workshop. The structure of the inner and outer surface of the lamps is partially uneven, damaged or deformed, which is not unusual for unpurified clay material that were used for making. The surface of the pottery was covered with ground coating, which was established by type of material testing (dissolution test) and mostly soft calcite layers. Further testing showed that pottery was tentatively in a relatively good shape if we take the making technology of that time and less purified clay with addition of quartz sand into consideration and the lamp colour was preserved only in traces. Since archaeological items are regularly placed under the ground surface the logical consequence is that they deteriorate with time since soil is more or less humid and contains calcium carbonate that settles on pottery finds. Presence of calcium carbonate was proven by applying one drop of 2% solution of chloride acid to the researched spot. On the basis of former conservatory research it was proceeded as follows i.e. cleaning, consolidation, fragments joining and finally conservation-renovation work was performed. Pottery was carefully cleaned by wet sponges to remove earth layers and preserve the remains of red coat. After having removed earth layers the lamps were mechanically cleaned i.e. various impurities were removed from the pottery surface, these were mostly calcite layers. Most calcite layers were not so solid and were removed by light scalpel scraping and needle sticking. The remaining layers of calcite carbonate that could not be removed mechanically were removed by applying 2% solution of chloride acide and by cleaning. After a short application of the solution and because of the porosity of the pottery the spots were immediately washed in water in order to prevent acid from getting into the pottery.
Since this is a low quality baked and coloured pottery it was necessary to harden -consolidate the material that was in a bad condition or the colour (in this case the remains of red coat). 5% solution of Mowilith 50 (ethylen N methyloacrylamyd vinyl-acetate) was applied as hardener. The fragments were first provisionally
joined with adhesive tape and then with ceramic glue Archaocoll 2000 soluble in acetone. As for the partially intact lamps, after the fragments had been joined the reconstruction was done i.e. renovation works of filling and construction of missing parts. Missing parts were filled with white dentist plaster of moderate solidity that is suitable for subsequent processing. Whenever this was possible, reconstruction was done by taking the plasticine print. For protection of joined ceramic fragments and certainly before applying plaster the area around the parts that should be reconstructed was previously protected by a coat of latex milk.
The procedure of removing the surplus of plaster was done by a small scalpel and ceramic scrapers whereas final step was to polish them with abrasive paper. Missing ears on lamp shoulders, oil holes, possible ornaments on discus, wide open canals that connect discus with lamp nozzle and seals i.e. bulging rings on the bottom of certain items were shaped both by hand and electric tools. Only lamps for which there were sufficient relevant elements such as dimension data (height, bottom, width, length, rim shape etc.) or corresponding data on their shape (number, shape and order of ears, sort of canals between the discus and nozzle of the lamp etc.) have been completely reconstructed. Plaster surface should be shaded i.e. patinated but before that it was previously impregnated. While some experts advise that items should be left with visible renovation traces i.e. unpatinated the others think that restored surfaces should be patinated for the aesthetic effect when the item is exposed to the public exhibition. However, the best way is to shade the renovated surface so that it differs from the genuine surface in one or two nuances so as to avoid an excessive contrast between the genuine and renovated part but still be able to see what has been restored. Consequently, both the museum visitors and important components of profession i.e. presenting Croatian archaeological treasure to the public must be taken into consideration.
Ključne riječi
Hrčak ID:
207343
URI
Datum izdavanja:
20.12.2011.
Posjeta: 1.176 *