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Conservation |
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Conservation Interventions
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The purpose of the interventions is to prevent stone from eroding and at the same time to restore the autonomy and static function of each architectural member. As a precautionary measure, the most vulnerable of the decorative sculptures were removed from the monuments in order to be exhibited in the Acropolis Museum (the Caryatids from the Erectheion, the Metopes from the east side, the West Frieze and pedimental sculptures from the Parthenon, and the Frieze of the Athena Nike temple).
The interventions are both systematic and preventive in nature. The conservation programme comprises a spectrum of work in the following main stages: diagnosis, preconsolidation, consolidation of the surface, removal of the damaging factors , and restoration interventions. |
Documentation
 All phases of the treatment together with all the information gathered about morphology, construction or earlier interventions are documented. The work itself is preceded by the diagnosis, an analytical study evaluating the condition of the surface to be conserved and the proposal of the treatment program. . Previous interventions, the types of stone decay, traces of historical evidence, incrustations, the monochromatic surface layers as well as the entire course of the work are all plotted to scale on architectural drawings. The whole process of the conservation interventions are well documented by series of photographs that are then placed in the archive. A journal of the works is likewise kept and digital recording of the photographs has now begun. |
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Preventive interventions  Prior to the works as a rule, the architectural members are dismantled and fragments are collected and recorded; the surfaces are consolidated and preconsolidation is carried out on areas that suffer crumbling, scaling or flaking. |
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Consolidation of the surface
 In the first stage of the treatment the marble surface is consolidated where it exhibits granular disaggregation or micro fissuring in depth, in order to slow down the deterioration process. The solution used is limewater with the addition of calcium carbonate. |
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Removal of failed past mortars  After consolidation, the past mortars that have failed or caused cracking and by-products are removed mechanically. The mortars are not removed from areas of the surface where this might cause further damage to the marble. |
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Removal of metallic pins from previous interventions
 The corroded iron or bronze dowels that had been set during the earlier interventions in order to bind fragments together are removed and replaced where necessary by titanium. The system for removing these rods has been developed by the marble technicians of the conservation teams. |
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Removal of rust stains  For the removal of rust stains left by the corroded reinforcements a neutral solution of thioglycolic acid is applied successfully. |
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Cleaning of fractures, cracks and delamination  Cleaning of fractures, cracks and delamination, εσωτερικών κενών και επιφανειών θραύσης γίνεται για την απομάκρυνση σαθρών τμημάτων, σωματιδίων και μικροοργανισμών. |
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Separating and re-attachment of fragments  In the case of fragments that are ready to fall off, or that remain in deformed state on the surface, the possibility of separating them is investigated according to individual situation and location. The criteria are preservation of the material and non-alteration of the surface geometry. In the case of larger fragments the bond is reinforced with titanium dowels wherever is needed. The binding mortar for fragments is white Portland cement low in sulphates. |
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Grouting of fractures, cracks and delamination  The grouting of fractures, cracks and delamination ensures the structural integrity of the architectural members. This is done using injections of grout, through a system of tubes. Injection grouts are constituted of white Portland cement, lime and in some cases with the addition of pozzolan. |
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Pointing the joints
Pointing the joints comprises the final phase and its purpose is to prevent the access of solid particles and rain water and to smooth out the surface discontinuities. The mortar used is a cement, lime and quartz sand mixture with the addition of pigments. |
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Protective coating |
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To protect the sculptures from the atmospheric pollution the only solution was their transfer to the Acropolis Museum On the other hand.to protect the surface of the monuments from the atmospheric pollutants a protective material should be applied. The requirements of this coating are the suspension of the sulphation the protection of the materials used in the conservation as well as the surface itself, without altering it, and at last the reversibility and compatibility with the marble. After a lengthy research programme, carried out at the laboratory of Science and Technology of Materials, Department of Chemical Enginnering, N.T.U.A., under the direction of late Professor Th. Skoulikidis, in which all the commercial protective materials on offer were rejected, a material based on n - semiconductors was designed. These are metal oxides that acquire the characteristics of the semiconductor when they are prepared electrolytically. Their action is based on stopping the conversion of marble to gypsum. It was found that aluminium oxide with reversible polymer as vehicle is the most effective. This material has been applied in a pilot-programme to a column of the Propylaia and to an inscription on the Acropolis rock. |
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Artificial patina  An artificial patina is employed in order to diminish the colour contrast between the new marble supplements and the ancient marble of the architectural members.
The composition of the material is derived from the basic idea of the protective material and consists of a polymer with the addition of electrolytically produced iron oxide and pigments. |
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Research
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| Of particular importance in the Conservation Section is research on the factors and the mechanisms of the decay and on the choice of conservation methods and materials. Collaborative research on special subjects is carried out by specialists, Universities and research institutions, such as the National Technical University of Athens (N.T.U.A.), the Institute of Geological and Metallurgical Research (IGME), the Hellenic Centre for Scientific Research NCSR "Democritus", the Hellenic Cement Research Centre (E.KE.T.), the Institute of Electronical Structure and Laser in the Technology and Research Foundation (FORTH-IESL), the Biology Department of the University of Athens, etc. The results of the research are as follows: |
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- For the first time titanium was employed in place of iron for the restoration of monuments, on the proposal of late professor Th. Skoulikidis.
- The mechanism whereby marble is transformed into gypsum through the activity of sulphur dioxide in the atmosphere was revealed in the National Technical University of Athens. It was found that the gypsum layer retains the details of the statues and sculptured decoration that had been obliterated from the surface of the marble and it was therefore necessary to preserve that layer. A method was then developed for stabilizing and inverting the gypsum back into calcite, the main component of marble. This is accomplished with a solution of potassium carbonate.
- A method was developed for reinforcing the lime used for consolidating the surface of the marble, with the addition of calcium carbonate as crystallization seeds.
- Grout injections composed of white cement and pozzolan were designed and applied in collaboration with the civil engineer A. Miltiadou -Fezans. These injections, which can be introduced into minute cracks, were applied to the columns of the Parthenon Opisthonaos (in situ). The structural restoration of the columns, which had never been dismantled, was thus achieved with the least possible intervention and disturbance.
- A method for cleaning the sculptured surface of the Parthenon West Frieze was developed using Laser. The FORTH-IESL developed an original system employing two wave lengths (ultraviolet and infrared) that could be applied either separately or simultaneously. This meant that the West Frieze could be cleaned in a safe and controllable way.
- A new material was developed for the protection of the marble surfaces from atmospheric pollution, based on n-semiconductors. The material has been applied successfully in a pilot programme initiated in 1995 on the Acropolis and its extensive application is expected. Likewise based on n-semiconductors, with the addition of pigments,, is the artificial patina applied to the new marble supplements of the architectural members.
- The problem of biodeterioration is being studied. To date micro-organisms on the monuments have been studied and identified in collaboration with Professor Krumbein and Assistant Professor A. Karagouni. Suitable biocides have been chosen and monitored and their effectiveness is being examined both in the laboratory and in situ in collaboration with Assistant Professor A. Karagouni (Section of Botany, Department of Biology, Athens University).
- Research on the effective consolidation and protection of limestone is in an initial phase. Relevant mineralogical analyses have already been conducted in collaboration with the IGME.
- Methods are being sought for combating agrobiological pests and higher plants in collaboration with the Benakeion Phytopathological Institute and the University of Athens.
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| Created by V.Fotopoulos |
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