Materials tested by time. Quality and durability of the restorations of the temples of Paestum from the nineteenth-century approaches to the contemporary issues of conservation

The issues linked to the physical, mechanical and aesthetical compatibility between pre-existences and additions, as well as to the durability of these latter, represent one of the main challenges of a restoration project. Furthermore, these actions become more complex within archaeological contexts, where more attention has to be paid in order to avoid the loss of the fragile ancient materials or any possible damages. Taking into account these premises, it is interesting to consider the archaeological site of Paestum – one of the most significant city of Magna Graecia, where structures and stratifications belonging to Greek, Lucan, Roman and Medieval Ages coexist – as a particular testing ground for the evolution of restoration principles and practical approaches [1]. In this case, in fact, a critical interpretation of the conservation proposals and of the restorations of the temples, carried out starting from the end of the 18th century, shows the high quality of the choices, all aimed at ensuring the compatibility between new and old materials, the durability of the additions, and their distinguishability. This awareness – gained over time through the experiences of many architects and technicians – brought to culturally advanced approaches, closer to the aims of the contemporary archaeological restoration also for the will to reduce the works to those indispensable to prevent the loss of the structures. As result of the in-depth knowledge of the material and mechanical properties of these ancient structures and of the hard fieldwork carried out during the first half of the 19th century, the methodological acquisitions and the practical skills showed an increased attention in the selection of those materials considered more compatible with the travertine of the temples. Among several experimentations – characterized by a high variability in terms of materials and constructive techniques –, it emerges, for example, the proposal by Francesco La Vega (1795) of strengthening a portion of an architrave using iron bars covered with «a good concrete», made of lime mortar, in order to prevent oxidations, or the choice to fill some shortcomings using the same travertine blocks fixed with visible iron clamps (Antonio Bonucci, 1805). Furthermore, it should be recalled the partial reconfiguration of the gables of the Temple of Athena with brick masonry in order to ensure the distinguishability of the new parts (Ciro Cuciniello, 1829-30), and the ability showed by Ulisse Rizzi (1849-60) in adding, only where indispensable, iron chains, limited portions of brick masonry or travertine blocks with well-smoothed surfaces, clearly different from the ancient ones. The results of the nineteenth-century restorations, nowadays still well preserved, show the quality of the technical expedients – aimed at preserving also the structural authenticity of the temples – and the durability of the materials chosen for the additions and acquire even more importance if compared with the outcomes of the twentieth-century yards. Despite that methodological lesson and similarly to what was happening in other archaeological contexts during the first decades of the Twentieth century, these works, in fact, were characterized by approaches less careful about the issues of compatibility and durability. As result, these interventions led to a larger use of concrete injections, reinforced concrete addictions, armed perforations, as well as undocumented reconstructions in correspondence of the city walls [2]. Taking these considerations into account, the paper aims at defining a critical interpretation of the evolution of techniques and approaches through the 19th century and, at the same time, at focusing the attention on the outcomes of the restoration yards carried out starting from the first decades of the 20th century. In particular, a critical comparison between the results of the nineteenth-century works and of those of the following century will allow to evaluate the quality of the choices in terms of durability and compatibility between old and new. These considerations will be carried on taking into account the present state of conservation of the temples, where it emerges, as a critical instance, that the most recent materials have answered to the test of time worse than the older ones only after few decades.