Conservation
Conservation is the process of repairing a damaged object and preserving it in a good condition. It is interrelated with archaeological excavation and the post-excavation study of archaeological finds. Archaeological conservation includes the examination, analysis, preservation, treatment and protection of the finds. At Kalaureia conservation has always been part of the overall plan for the site, where archaeologists and conservators have a close collaboration for the well-being of the finds.
The main principles underlying conservation at Kalaureia are reversibility, minimum intervention and preservation of evidence/possible information available. The finds from the Sanctuary of Poseidon that go to the conservation laboratory have been mainly of inorganic materials: metals, such as copper alloys, iron and lead objects; ceramics; stone objects; and glass objects. On-site conservation is also conducted when necessary (e.g. support of the fragile walls of a cistern).
Conservation of Archaic cistern. B. Wells.
In the lab, careful examination under magnification of each find takes place before treatment begins, so that the condition of the find before treatment can be assessed. Depending upon the condition of the find and the importance of the information it conveys, the archaeologist and the conservator then decide about the necessity and priority of treatment. If an object needs to be scientifically analysed, it is first analysed and thereafter receives treatment if necessary.
For the objects that are going to be conserved, detailed recording of their condition and photography are done before treatment. Conservation treatment always aims at using the least possible chemical materials for conservation; this is because they can never be totally removed from the object and thus, they could harm the object in the future and/or interfere with a future analytical investigation.
Bronze fish-hook before and after conservation. M. Tziotziou and C. Mauzy.The selection of conservation treatment not only depends on the condition and the material of the object but always also on whether the object is to be displayed or not. Objects to be displayed require a treatment that not only stabilises them but also improves them aesthetically (e.g. an incomplete ceramic vessel that is going to be studied only, will not be gap-filled; if intended for exhibition, gap-filling and painting of the filling might be required).
Mechanical cleaning is always done first. If this is not sufficient (and only when necessary) chemical cleaning follows. For metals, investigative mechanical cleaning is always operated under the microscope.
Ceramics, architectural terracottas, glass and stone objects are first washed in deionised water baths to remove excess soil and then undergo desalination if possible/necessary. The removal of salt encrustations is first attempted mechanically (when feasible) and then chemically (if necessary). Any further conservation treatment, following cleaning, is carried out afterwards according to the special needs and the nature of the object.
When treatment is completed, the maintenance of the treated item plays a critical role for the duration of its lifetime. Controlling the environment of the storage area or the display case is a key factor for good maintenance. This is not always an easy task and often requires very sophisticated methods to be adopted. In the Archaeological Museum of Poros, where the conservation laboratory and the storage area are located, great effort is spent to give the finds the best possible maintenance. Humidity in Poros is very high and the building is old with limited possibilities. It is not feasible to achieve the best environmental conditions.
For inorganic material, the safe levels of relative humidity (RH) should be in the range of 45–60% (metals should be kept at RH<15%), temperature at 19±1ºC (winter) and 24±1ºC (summer), light should be less than 250 lux and UV radiation less than 75 μW/lm. The storage area or the display case should be well-aerated to keep the air pollution at low levels. (G Thomson, The Museum Environment, Second Edition. Butterworth-Heinemann, 1986).
After having been separately placed in perforated polythene bags, metals are stored in closed plastic containers together with silica gel. This a desiccant material, placed in perforated polythene bags. It needs to be changed when it becomes saturated with moisture and in order to keep the relative humidity at safe levels (less than 15%).
For ceramics, stone objects, architectural terracottas and glass, placement in perforated polythene bags within a well-aerated and stable environment is sufficient. Labels are of acid-free paper. Good packaging of delicate or fragile objects is essential and is carried out using different "cushioning" materials.
Finally, full documentation (written reports and photographs) of all the treated items is done. The condition of the find before and after treatment is registered as well as the methods of conservation. Handling and maintenance instructions are given.
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