Naples, complex restoration of Alexander's Mosaic at the Battle of Isso has begun

A complex intervention on Alexander's great mosaic at the Battle of Issus, an iconic masterpiece of the museum and of all Roman art, starts today at the National Archaeological Museum in Naples.

Restoration of the famous Mosaic of the Battle of Isso, one of MANN’s most iconic works, began today at the National Archaeological Museum in Naples. The restoration will be carried out under the supervision of the Central Institute for Restoration (ICR); diagnostic activities are promoted in a network with the University of Molise (UNIMOL) and the Center for Research on Archaeometry and Conservation Science (CRACS). The start of the site was attended by Paolo Giulierini (MANN Director), Amanda Piezzo (Technical Director of Mosaic Restoration Works), Antonio De Simone (Scientific Director of Works), Maria Teresa Operetto (MANN Restoration Laboratory Manager) and Claudia Carrer (Partnership, Alliances/ TIM Project Manager).

The mosaic, which decorated the great floor of the exedra of the House of the Faun in Pompeii, was at the center of a rich iconographic “architecture.” Discovered in 1831, the masterpiece not only revealed itself already at the time as unique in terms of size and iconography, but also for its excellent state of preservation: in fact, the large gaps found concerned the left section of the work, without “affecting” the fulcrum of the depiction. It was troubled, in any case, the decision to detach the mosaic, in order to transport it to the then Royal Bourbon Museum: after about 12 years of heated debate, a commission expressed a favorable opinion, and the work, on November 16, 1844, was packed and driven slowly from Pompeii to Naples, on a wagon drawn by sixteen oxen. The integrity of the mosaic was threatened by an accident that occurred at Torre del Greco, when the crate fell to the ground, but the masterpiece was not damaged.

The work was first placed on the floor of room CXL, according to Pietro Bianchi’s initial design. Then, in 1916, Vittorio Spinazzola, devised the new arrangement on the wall, in the rearranged mosaic rooms. Since then the mosaic has not moved, becoming one of the symbols of the museum.

The reasons for the restoration

The restoration started today is very complex: preservation, placement, weight (probably seven tons) and art-historical relevance of the artifact in fact make the operation very delicate. The Alexander mosaic has several critical conservation issues, consisting mainly of detachments of tesserae, surface lesions, swelling and lowering of the surface. In particular, the central right area is affected by a visible depression; punctual swellings are present along the perimeter of the mosaic, probably due to oxidation phenomena of the metal elements of the wooden framework put in place during the 1916 transfer. Also present are microfractures with vertical and horizontal trends, as well as a diagonal lesion, already the subject of veiling during previous restorations. In the last twenty years, the need for an overall restoration became clear thanks also to the diagnostic investigations carried out: the conservation reasons were combined with the needs for a better organic reading of the work.

The intervention, of course, was preceded by a thorough diagnostic campaign. In 2015, with the contribution of IPERION and CNR-ISTI of Pisa, technicians documented the state of the work, in relation to the constituent materials, distinguishing them from those attributable to restorations carried out in ancient and modern times. In 2018, with the participation of the University of Molise and the CNR, a detailed survey of the mosaic was carried out, using high-resolution photogrammetry: the three-dimensional model of the work was supplemented by a georadar survey to verify the condition of the support. These operations also made it possible to highlight fractures and cracks not visible to the naked eye, as well as anomalies in the constituent layers of the support.

Studies have shown that the deterioration phenomena are probably due essentially to the oxidation of the iron supports of the mosaic and the degradation of the mortars: the accentuated depression affecting the central/right part of the mosaic panel can be attributed to these factors. This state of affairs is certainly aggravated by the weight of the mosaic and the vertical position, both causes to which the downward sliding of the most superficial layer of mortar and tiles can be traced. In order to get an exhaustive picture of the actual condition of the work, a new campaign of diagnostic investigations has been planned, carried out by the University of Molise and CRACS (Center for Research on Archaeometry and Conservation Science); the investigations will also affect the executive phase of the restoration. Special attention will also be paid to microclimatic and environmental conditions, not only to understand their possible incidence in the process of degradation of the mosaic, but above all to identify the best future exposure conditions, in terms of lighting and thermo-hygrometric parameters.

The phases of the intervention

The restoration project is characterized by the principle of minimal intervention and is aimed at preserving the material integrity of the work in its current state. The intervention will be divided into two different phases: between the two moments, technicians will move the mosaic. The handling is necessary to explore the part behind the Battle of Isso, verify the state of the support and fully define the overall conservation interventions to be carried out. In the first phase, the hypothesized intervention, which will be carried out in situ by setting up a visible site, is aimed at securing the mosaic surface prior to the handling of the work. In this phase, the mosaic will undergo careful visual and tactile inspection of the entire surface, preliminary to the subsequent work; pre-consolidation of the detached tesserae and mortar layers; cleaning; and veiling with suitable support bandages over the entire currently visible surface.

At a time immediately thereafter, after affixing a protective wooden planking as well as a suitable metal support frame, the mosaic will be removed from its current location by means of a specially designed mechanical handling system. The direct investigation will be accompanied by further instrumental analysis, thanks to which the restoration interventions hypothesized in the first phase of the design will be defined, establishing the actions to be performed on the support to ensure the preservation of the artifact.

Instead, the second and final executive phase of the restoration will involve, first, the support of the mosaic: the works will be carried out, therefore, on the back surface of the work (the mosaic tesserae, at this time, will not be visible because they will be covered by the protective wooden planking). A significant contribution in terms of new services and platforms was provided by TIM, in collaboration with NTT DATA. The company has made available, on an experimental basis, digital solutions that allow the use of new technologies for restoration, thanks to the simultaneous processing of data acquired during the diagnostic phase. Thanks to these technologies it will be possible to reproduce, according to various levels on the body of the mosaic, all the technical information useful to perform the restoration to be visualized in real time with virtual and augmented reality solutions. The applications, together with a control console, will make it possible to use a smart visor to be worn to frame the part of interest of the mosaic on which to intervene: the restorer, in this way, will always have his hands free to operate and, more importantly, will be able to work on the rear part of the work, checking at all times any effects produced in the front layers of the artifact.

The instrumentation will allow, with a methodology similar to that used in surgery, the projection in scale 1: 1 of the front part of the mosaic onto a special surface, which could be a wall or a cloth placed on site (which will not only be a working tool for the restorers, but will also make what is happening on the site usable to the public), and the association to the projection of a series of geophysical parameters deduced from the investigations (which can be interrogated by the operators in real time, analyzing all the data inherent to the artifact as a whole). Once the intervention on the support is finished, the restorers will remove the bandages placed during the initial intervention phase and complete the restoration with cleaning operations, further and possible consolidation, and final protective treatment. The restoration project, thus, will also be an opportunity to enhance, also in the perception of visitors, not only the complex path of research, but also the methodology adopted (the progressive, punctual and careful dimension of the different phases of work, will be an essential component to emphasize the interconnection of contributions and professionalism, at the basis of an event of international importance).

The statements

“With the start, in 2021, of the restoration of the Alexander Mosaic,” says MANN Director Paolo Giulierini, “we write together an important page in the history of the National Archaeological Museum of Naples and therefore of the conservation of cultural heritage. It will be a grand restoration, which will be accomplished before the eyes of the world. An exciting seven-month-long journey awaits us: after the meticulous preparatory work, scholars and experts will take care with the most advanced techniques of our iconic Pompeian masterpiece, depicting the famous Battle of Issus. Technology and digital platforms will allow us to follow the delicate operations, step by step, in a kind of ’transparent construction site’, as never before. To carry out such an ambitious and complex operation, a network of scientific collaborations and partnerships of great prestige has been activated by MANN.”

“It takes courage to tackle a restoration of this kind, the courage that this great personage, who set out to conquer the world, conveys to us,” Giulierini adds. “A courage that was partly lacking in earlier times, that of posing the problem of Alexander’s mosaic. I thank Prof. Antonio De Simone who immediately stressed to me the urgency and importance of this restoration, our architect Amanda Piezzo. The Museum, with its restoration laboratory led just from today by Maria Teresa Operetto, has not closed in on itself for this undertaking. We are working together with important scientific partners, universities, TIM in collaboration with NTT DATA, and a technology that is combined with the daily miracle of the hands of our restorers. It will be a ’transparent’ restoration, visible to visitors when the museums reopen and in some stages even online. All together we take this great responsibility, in coordination with the Central Institute for Restoration (ICR) directed by Alessandra Marino, whom I thank. In a year’s time we will organize the great exhibition Alexander and the Indies Way, with the Campania Region. Because our museum, a symbol of Italian archaeology in the world, looks East and West.”

In the photograph: restorers at work on the Alexander mosaic. Ph. Credit Marco Pedicini

Naples, complex restoration of Alexander's Mosaic at the Battle of Isso has begun
Naples, complex restoration of Alexander's Mosaic at the Battle of Isso has begun

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