By: Max Cardillo, 10/21/2012
From 1921 to 1933 Nikolaos Balanos, an engineer, led a large-scale project, the restoration of the Acropolis in Athens. The techniques he used, though commonly employed in the early 20th century, have proved to be very problematic. He used modern Portland cement mortar and unprotected steel reinforcements as stone clamps and in reinforced concrete elements. These materials, a few decades later, started to deteriorate, causing damage to the original structure. He also was engaged in a certain amount of anastilosis, which was not well researched and ended up placing material in positions that were not the original.
Unlike ancient Greek builders, who covered rought iron clamps with lead to protect them from rusting, in the early 20th century unprotected steel was used, often embedded in hard Portland cement. As the steel oxidized, creating rust crystals with a larger volume that the original steel, the expansion against hard cement created pressure on the ancient stone work, often generating cracks and staining.
By 1975 it became necessary to begin a new large-scale restoration program, the ongoing “Acropolis Restoration Project,” which to a great extent has been involved in correcting the restoration work done under Balanos half a century earlier. It involves:
- Dismantling most of the structures earlier restored;
- Removal of all the inappropriate materials placed during previous restorations;
- Carefully studying and documenting the components and materials to determine as much as possible where they were originally located and their source;
- The study of the construction techniques used in the original buildings and also in later modifications and restorations;
- Reassembling the buildings using the old stones, new stone infills, and consolidating materials that are compatible with the old structure.
- Clean dirt and repair damage caused by modern atmospheric pollution.
One interesting feature of the restoration is the infill stonework, which is very visible against the original material. The new infill replaces missing stonework that created structural or visual gaps in the anastylosis of the building. In the previous restoration, these areas had often had been filled with original stones that were not in their correct location. The new infills as the original are in Pentelic marble, but being new, have a much lighter coloration and are often placed in slight relief against the original stone. This feature highlights the difference between the original and new stone, which is consistent with modern restoration ethics. These require that the viewing public be able to easily perceive what is original material and what has been added during the restoration.
In the photographs from the Acropolis restoration workshop, one can see images of restorers removing old clamps from stone blocks, blocks that have been partially completed with new stone patches, a new stone patch being made using a sculptor’s pantograph, a traditional technique.