Conservation of the Parthenon
The condition of the architectural members of the Parthenon is due to a combination of historical events, the most important of which are considered to be the fire of 287 B.C., vandalism and the explosion of 1687. In more recent historical times, unsuccessful interventions of conservation and restoration, extensive atmospheric pollution, mainly from 1950 on, have deteriorated the monument's condition. The state of preservation of most of the monument's architectural members is characterized by various sorts of damage, disintegration and flaking, thermal expansion and sulphation, biodeterioration, fractures, cracks and delaminations, extensive pointing with Meyer cement. The first pilot project of systematic interventions carried out in 1988 and was focussed on the second column from the north in the east end of the temple. Following that, the conservation programme of the monument was planned and developed in coordination with the broader restoration programme.
The interventions are focussed on the following:
Conservation of the Erechtheion
The forms of deterioration which are observed on the Erechtheion are similar to those observed on all the Acropolis monuments, the chief characteristics being surface areas that are crumbling with a notable microbiological presence and networks of micro-cracks. This condition is a direct result of the interaction of many factors, such as the composition of the stone itself (e.g.aluminosilicate veins), natural destructive phenomena (for example weather conditions), acidic attack, violent destructions suffered by the monument (fires in antiquity, earthquakes) and the earlier interventions for restoration and consolidation. All this has resulted in the gradual alteration of the material and the diminishing of both morphology and geometry of its architectural members.
The Erechtheion has gone through repeated interventions for restoration and conservation. The most recent effort to conserve the surface of the monument systematically began in 1995 (under the supervision) of the ESMA, eight years after the completion of the structural restoration programme. The purpose of the present intervention is to consolidate the surface of the marble of the Erechtheion and, by so doing, to reinforce the monument's longevity. The criteria for choosing which parts of the monument should undergo either systematic or preventive interventions are the extent, the intensity, the diversity of form and the pace of evolution of the decay. On the basis of these facts, the porch of the Caryatids, five columns of the east porch of the monument, the west part of the outer face of the north wall and the inner face of the south wall were chosen. The conservation of these areas of the monument has already been completed.. At the same time, preventive work was carried out on the threshold of the north doorway of the monument, the floor of the east porch, two beams of the ceiling of the north porch and on the ceiling of the south porch. Systematic interventions are being carried out on the south part of the inner and of the outer face of the west wall of the Erechtheion.
Conservation of the Arrephorion
West of the Erechtheion is the so-called "House of the Arrephoroi", of which only the limestone foundations are preserved. In order to determine the mineralogical composition of the stones, samples were analysed at the Institute of Geological and Metallurgical Research (IGME). The stone was found to be mainly micropsammitic limestone and dolomite. The state in which the stone is preserved is related to its composition and different deposition phases, as well as to erosion caused by rain water and the salts in dampness from the ground. A considerable number of the stones have been broken into pieces, while others are flaked and cracked, particularly along the lines of veins and deposition layers. Pulverization of the material is particularly extensive mainly in the lower courses of the foundations. Likewise evident are clusters of holes with both large and small diameters. A biological crust is particularly evident on the upper surfaces of the stones, while a black crust has formed to a limited extent in areas protected from rain water.
It was decided to backfill the foundations in order to protect them from the action of erosive factors. The following works were carried out as preventive conservation preceding the filling:
recording of the state of preservation
securing fragments that are ready to fall
collection of fragments that have fallen. In most cases it is virtually impossible to identify them as their edges are altered.
consolidation of the surface.
An inorganic material that is compatible with the building material of the foundations is being sought for joining the fragments and filling the cracks and delamination.
Conservation of the temple of Athena Nike
During the present restoration programme a great number of the architectural blocks were fragmented. The dismantling of the blocks revealed a great number of smaller fragments due to the mechanical pressure from the expansion of the steel junctions.
The time-frame for the completion of the restoration of the temple was tightso, until the completion of the structural restoration, immediate priority interventions are applied to all the blocks. These interventions include the consolidation of areas that are crumbling and pieces that are ready to fall as well as the joining of fragments that were collected while the members were being dismantled. Thorough conservation interventions are being carried out only in areas that will be inaccessible to the conservators after the anastelosis of the temple.
The surfaces of the temple's columns are in a bad state of preservation with flaking, cracks, many pieces ready to fall off and particularly damaged edges. It was therefore considered necessary to complete the conservation interventions before the columns were reset in place.
The conservation being carried out in the framework of this programme will enable the architectural members to be returned safely to their original positions in the monument.
Conservation of the Propylaia
The Propylaia are built of white Pentelic marble on a foundation of yellowish poros. Grey Eleusinian stone was employed for decorative effect. Characteristic of the Propylaia marble is the significant geological heterogeneity. The non-calcitic inclusions are responsible for specific alterations and successive flaking. A similar form of deterioration is not encountered on the other Acropolis monuments.
Conservation was carried out initially on the toichobate of the interior of the Pinacotheke of the Propylaia, on columns in the west hall and on ceiling coffers in the central building. Today conservation of the surface of the Propylaia follows and supports the work of anastelosis with preliminary consolidation and systematic conservation of the surface of the architectural members in situ or after their dismantling. In addition systematic conservation is being applied to architectural members that are not included in the restoration programme but have severely damaged surfaces.
The surfaces that are being conserved as part of the present programme of anastelosis of the monument are those of the east façade and the south wall of the east colonnade, the doorway wall of the central building, the lintel of the doorway wall, the north wall of the central building, the columns of the Ionic colonnade, the Ionic column capital from the Balanos anastelosis and the coffers and beams of the ceiling of the central building.
Conservation of the West Frieze of the Parthenon
The west frieze is part of the Parthenon frieze that encircled the upper part of the cella walls and the columns of the pronaos and opisthonaos. It comprises 16 blocks, the first and second of which are in the British Museum. The frieze slabs have suffered mechanical stress and damage from the vandalisms, from the failure of previous interventions and from atmospheric pollution.
In 1978 the frieze was sheltered in an effort to avoid acidic attack on the sculptured surface and the washing out of the gypsum formed. The result of this choice was the covering of the surface of the slabs with deposits of soot and black incrustation. In 1992-93 the frieze blocks were dismantled and transferred to a specially constructed laboratory in the Acropolis Museum, so that their conservation could begin.
Conservation of the blocks began in 1999 and was successfully completed in 2005. Initially the work was focussed on structural restoration of the blocks, in the course of which fragments were joined, the surfaces were consolidated and the mortars and pins of earlier interventions were removed. The surface was then cleaned of soot deposits and the black incrustation. Following a comparative study of four cleaning methods (microblasting, absorptive poultices, gypsum inversion and laser), cleaning by laser proved to be the most effective in all cases of deposits and substrates (monochromatic surface layers and marble). The cleaning system was designed and developed by the Institute of Electronical Structure and Laser of the Technical and Research Foundation , Crete. This is the laser type Q-switched Nd: YAG. The prototype system can emit both at two wave lengths (infrared 1064nm and ultraviolet 355nm), individually or simultaneously.
At the end, the joints were pointed in order to smooth out the surface discontinuities. The blocks of the west frieze are now on exhibition in the Acropolis Museum. Copies of artificial stone have been set in their place on the monument.
Sculpture conservation laboratory
The sculpture conservation laboratory of the Acropolis Museum was established in 1982 by the First Ephorate of Prehistoric and Classical Antiquities. Among the first concerns was to group and arrange the fragments of sculptures in the storerooms, organize the conservation archive and file the photographic material. The fragments of the sculptures were then arranged in the Cour Anglaise in the south part of the Museum.
The following works are carried out in the sculpture conservation laboratory:
research on the identification of the fragments
systematic conservation of the sculptures
construction of bases and supports for the sculptures
up-dating the conservation and photographic archives
preparing sculptures and constructing support bases for temporary exhibitions, in Greece and abroad
The above works are carried out in full respect for the principle of reversibility.
Preparation of the sculptural decoration of the Parthenon (metopes, frieze and pedimental sculptures) and other objects for exhibition in the New Acropolis Museum was initiated in 2001. These works made it necessary to amplify the laboratory, from 2003 on, with personnel from the Organization for the Building of the New Acropolis Museum.