By Gaël de Guichen and Roberto Nardi

In some sense, mosaic conservation is a practice as old as the making of mosaics themselves. Today one can still find ancient mosaics with patches that were made as part of maintenance when the floors were still in use. In more recent centuries, restoration was widely practiced on objects of antiquity, including mosaics. And from the first decades of the twentieth century, we have fine examples of restorations.

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Prior to the mid-twentieth century, discoveries of mosaics happened mainly during archaeological excavation of known sites. The postwar period in Europe was a time of tremendous construction and reconstruction, and discoveries of mosaics occurred more frequently throughout the continent. That does not mean these artifacts were ultimately preserved. According to a 1971 study made by Claude Bassier, a French engineer, of 660 pavements found in France and published by archaeologists, at least 92 percent were abandoned, destroyed, or lost. The remaining ones—when the subjects were figurative and considered valuable—were, according to the traditional techniques of the time, systematically removed from archaeological sites. Some were re-laid on concrete slabs, while others were abandoned in storage, where many remain today.

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In the early postwar period, strategies for mosaic conservation were very limited—detachment was the primary option available. Interventions were typically undertaken without adequate planning and with a workforce that consisted mainly of artisans, craftspersons, or carpenters. Conservation practice was based solely on empirical knowledge, and the materials used by practitioners were limited to cement, gypsum, and glues. In addition, documentation was lacking. Practitioners worked in isolation, without the benefit of professional associations. An exception to the typical treatment of excavated mosaics was the completion of the excavation of the Villa Romana del Casale in Piazza Armerina, Sicily, in the late 1950s; there Cesare Brandi introduced the solution of conserving the villa's remarkable mosaics in situ and protecting the entire site.

A third significant figure who advanced the field technologically at an early date was Antonio Cassio of the Istituto Centrale per il Restauro in Rome. Cassio—a mosaicist from a family of mosaicists—preferred a more sensitive and controlled method for detaching mosaics. He used a system typical of mosaic making itself, which permitted the detachment of mosaics in pieces averaging twenty-five square centimeters. This method substantially reduced cutting stresses—and therefore reduced damage to mosaics being lifted.

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In the late 1960s, again in Italy, a different field—mural painting—was undergoing a theoretical and practical reevaluation, which would subsequently have a direct and important impact on mosaic conservation. In 1968 ICCROM (International Centre for the Study of the Preservation and Restoration of Cultural Property) joined with the Istituto Centrale per il Restauro to initiate an annual four-month course on the conservation of wall paintings. Initially the highlight of the course was the detachment of a wall painting, but very quickly, in situ consolidation was embraced as a more appropriate method, as wall paintings came to be considered an integral part of the buildings to which they belonged. This evolution in wall paintings conservation led to the publication in 1977 of Conservation of Wall Paintings by Paolo Mora, Laura Mora, and Paul Philippot, still a fundamental book for the profession.

Establishing the ICCM

All this was in the air in 1977 when the first meeting on mosaic conservation—with forty-five participants—was organized in Rome. At the end of this conference, ten of the participants decided to create the International Committee for the Conservation of Mosaics (ICCM) and to act as its first board. The publication of the proceedings of the meeting was called Mosaic No. 1: Deterioration and Conservation, and it was addressed to conservator-restorers, archaeologists, technicians, administrators, and the public. Another important result of the meeting was a recommendation to launch a course on mosaic conservation.

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The 1977 meeting in Rome was the starting point for a series of regular conferences. The following year, the Institut National du Patrimoine in Tunisia hosted the second conference and went on to host subsequent meetings of the ICCM board. Other iccm conferences followed. The latest conference, the ninth, took place in Hammamet, Tunisia, in 2005 (see p. 20). Following each of these meetings, the proceedings were published. In addition to the proceedings, twelve newsletters have also been published. These materials represent for the profession a basic source of information that did not exist fifty years ago.

The evolution in the thinking of the ICCM—and, indirectly, the trend in its professional principles—is reflected in the themes of each of those conferences (see sidebar). It is evident from looking at those themes that by 1983 the iccm was pointing out the importance of in situ conservation and encouraging its use whenever possible. In this way, it mirrored an evolution already followed by wall paintings specialists.

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Another principle that the ICCM has come to strongly support is the rejection of the use of cement in the conservation and restoration of mosaics. It had been clear for some time that the use of cement in the conservation of ancient monuments risked an expansion of damage. In response, Italian conservation scientist Giorgio Torraca launched research in 1980 to replace cement with, paradoxically, one of the oldest construction materials known—lime-based mortar. However, even within the ICCM, it required almost ten years of heated debate before lime-based mortars were generally accepted and before they replaced cement applied in direct contact to mosaics. The use of lime-based mortars has allowed the development of in situ consolidation and furthered the practice of maintenance in situ when possible. (Unfortunately, despite the abundant evidence of destruction caused by cement in conservation interventions, this material is still used on mosaics—and worse, its use is still occasionally taught as a technique in some countries.)

One other important advance that can be credited to discussion and reflection during several iccm conferences was the acceptance by conservation practitioners of a planned approach to safeguarding mosaic floors. In 1996 a question-driven flowchart was developed to help practitioners determine which of several options would be most appropriate to a particular context and set of problems. The questions related to risk, visitation, significance, available resources, and archaeological investigation, and they led to consideration of a range of options, including backfilling, lifting and transferring to a museum, lifting and re-laying in situ, and consolidation in situ.

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The previous standard practice of leaving a mosaic on site without protection—or of lifting the pavement and abandoning it in storage—was clearly the result of a lack of planning, as well as demonstrative of the attitude of some archaeologists, insensitive to conservation, who felt that their work ended the day they published their findings. A systematic analysis of practical conditions can help determine different and more appropriate approaches for dealing with an excavated mosaic. With any of these options, serious planning before implementation is required.

After the three ICCM conferences dedicated to in situ conservation, the four subsequent conferences referenced in their titles the issues of public presentation of mosaics. As early as 1977 it was suggested in Mosaic No. 1 to involve the public "so that specialists responsible for conservation receive support from individuals. It is the public, after all, that benefits and is served by the world-wide conservation movement." This statement established in the mosaic conservation field the recognition that an objective of the conservation profession is to present and to interpret for the public the cultural properties that we are engaged in conserving.

In order to influence the actual practice of mosaic conservation, these new ideas and approaches required adequate training at all levels. Yet the development of training did not happen quickly. Twelve years passed after the 1977 recommendation for training before the first course for decision makers was initiated. The one-month course—organized by ICCROM in 1989 in Rome—was attended primarily by archaeologists. Today some of the participants of that early course are members of the ICCM board.

Since that time, several courses at various levels have been—and continue to be—organized. While this activity is generally welcome, certain doubts exist regarding their efficacy. Some of these sessions are too short—lasting a few weeks at most—or the trainers lack the teaching abilities required. In some instances, the production of new mosaics is taught at the same time as conservation techniques—a questionable pairing.

An example of training appropriately adapted to the challenge faced is the technician training program launched by the GCI and Tunisia's Institut National du Patrimoine in 1998 (see Conservation, vol. 17, no. 1). This long-term involvement in training technicians in the care and maintenance of in situ archaeological mosaics is attempting to enhance the ability of cultural authorities in Tunisia to preserve the wealth of mosaic heritage found in that country.

A Maturing of the Profession

For the mosaic conservation field, the last fifty years constitute a period of great change and maturation. The creation and development of the ICCM have advanced the work begun by the Association Internationale pour l'Etude de la Mosaïque Antique (AIEMA) and later developed by the Association for the Study and Preservation of Roman Mosaics (ASPROM) in Great Britain and the Associazione Italiana per lo Studio e la Conservazione del Mosaico (AISCOM0 in Italy.

Unlike three decades ago, the scope of mosaic conservation is no longer restricted to a few square meters of tesserae recently excavated or on exhibit in a museum. Today it has expanded to include entire architectural complexes or sites where thousands of square meters of mosaics are in danger. And today the conservator is joined by other professional figures in the field of conservation in addressing the problems of mosaic conservation. Among them are conservation scientists who share an interest in finding solutions to mosaic conservation globally—and not simply through the lens of a microscope. The fact that 250 colleagues from thirty countries—and with many different backgrounds—attended the ninth ICCM conference indicates that common problems exist and that the interest to solve them collectively is very high.

At the same time it is evident that there are still issues that have not been resolved, and a great deal of work remains to be done. There is an urgent need to properly conserve and store hundreds, if not thousands, of mosaics previously re-laid on reinforced concrete or abandoned in storage. Reburial of mosaics is an important tool for preserving mosaics, but it requires clear protocols and a technical and financial assessment. Further research on the protection of mosaics from biological growth would contribute to mitigating a widespread problem confronting the preservation and presentation of mosaics. Studies of the cost of maintenance of mosaics in situ are needed to help promote this approach. Assessments of training needs for archaeologists, conservator-restorers, and technicians are essential to ensuring long-term protection of mosaics. And finally, the publication of a major book on the conservation and restoration of mosaics is long overdue.

The above issues are only some of the challenges faced by the professionals charged with the responsibility for conserving and exhibiting mosaics. There is still a long way to go. Nevertheless, it is realistic to look to the future with a feeling of optimism. With the help of the ICCM, the great vitality demonstrated by the profession has resulted in standards of mosaic conservation practice today that appeared almost unreachable thirty years ago. Much has been accomplished, and those accomplishments form an essential foundation for the work that lies ahead.

Gaël de Guichen is honorary president of the ICCM and former program director and assistant to the director general at ICCROM. Roberto Nardi is vice president of the ICCM and the founder of the Centro di Conservazione Archeologica in Italy, a private company working in the field of conservation of archaeological sites and monuments.

Conferences of the ICCM

Rome, Italy, 1977: Deterioration and Conservation

Tunis and Carthage, Tunisia, 1978: Safeguard

Aquileia, Italy, 1983: Conservation In Situ

Soria, Spain, 1986: Conservation In Situ

Palencia, Spain, 1989: Conservation In Situ

Faro and Conimbriga, Portugal, 1992: Conservation, Protection, Presentation

Nicosia, Cyprus, 1996: Mosaics Make a Site: The Conservation In Situ of Mosaics on Archaeological Sites

Saint-Romain-en-Gal and Arles, France, 1999: Mosaics: Conserve to Display?

Thessaloníki, Greece, 2002: Wall and Floor Mosaics: Conservation, Maintenance, and Presentation

Hammamet, Tunisia, 2005: Lessons Learned: Reflecting on the Theory and Practice of Mosaic Conservation