By Jeffrey Levin

To catch a glimpse of some cultural treasure of the past does not necessarily require a visit to a museum or a trip to a distant archaeological site. Sometimes it happens when one does not expect it—while rounding a city corner on foot, driving through an unfamiliar town, or passing a place one has been to on a thousand occasions but suddenly really sees for the first time.

The places people live are often interlaced with elements of cultural heritage—from the entire core of a historic city to a single structure to a work of art that in the midst of living spaces defines those spaces and forms a part of their history. For many in communities across the globe, these kinds of surroundings are part of the texture of their lives—perhaps acknowledged, perhaps not, but present nonetheless. Because they form part of daily life they can play as much—if not more—of a role in providing a sense of identity for a community as objects viewed behind glass cases or ancient ruins seen through a fence.

While this proximity to people gives historic structures and cities life, it places strains on their preservation. As inhabited places, they are exceedingly complicated to conserve. Unlike museum collections and archaeological sites, they cannot be isolated from use or modification. Historic city centers are subject to the legitimate demands of their populations for the components of modern urban life, such as transportation, plumbing, electricity, and telephone service. Similarly, inhabited historic buildings cannot and do not remain unchanged over time. They, too, are subject to adaptation as residential needs change.

Making a historic city a modern one without losing or diminishing its unique character is an enormous conservation challenge. When car and bus traffic crowds narrow streets originally intended for foot traffic, when telephone lines and commercial signage obscure centuries-old facades, when pollution, overcrowding, and poor maintenance accelerate the process of deterioration, and when mass tourism brings with it not only increased revenue but an alteration in the traditional commercial life of the community, the conservation problems and solutions are far more multifaceted than those of a painting or an archaeological site.

Any effort to preserve historic cities requires attention to the real social and physical needs of the contemporary population, as well as the economic realities of the community. As living places, historic cities are more than the sum of their structures—they encompass a cultural life as well. Integrated with the physical are customs and traditions, social and economic relationships, religious functions, and political life. Conservation in historic cities is both a physical and political process. To succeed, preservation programs must have the understanding and support of those who make these cities their home. Such programs cannot simply adopt the standards of museum conservation or archaeological site management. Rather, the conservation of historic cities requires its own standards and processes that recognize what is practical and possible while still striving to preserve authenticity.

The GCI has embraced an approach to the conservation problems of historic cities that involves working with local agencies, governmental and private, to develop strategies that capitalize on the cultural asset represented by the historic core and that use incentives for social and physical investment as part of the preservation process. An important component of this effort is increasing public awareness of the importance of conserving the historic core and eliciting public participation in decision making.

It is not only the preservation of historic cities as a whole but individual historic structures as well that has been of concern to the Institute. Among the threats to historic structures in many places is the destructive power of earthquakes. The conservation challenge in coping with this threat is developing ways to strengthen structures while maintaining their historical integrity. Consistent with the disaster-preparedness activities it has conducted, the GCI is engaged in several projects to research and develop measures that add to a building's ability to withstand seismic stress without destroying or diminishing the very features that make a structure worth preserving.

Within historic structures are works of art that pose their own complex conservation problems, depending on the materials that compose the works and the specific conditions of their settings. In this area, the Institute has selected projects where culturally and historically significant art is threatened and where technical problems of interest or importance are involved. While each project has presented a different technical challenge, the philosophy behind the treatment of these works has been the same—to clean, consolidate, and preserve (rather than "restore") and to find ways to protect these works over the long term from the forces damaging or destroying them.

Conservation of cultural heritage in outdoor settings presents complex challenges, particularly if that heritage is part of a living community. Without question, the conservation of this heritage is complicated by factors that extend well beyond technical conservation concerns. The GCI believes that finding the appropriate balance between the social and physical needs of a historic community and preserving its architectural and artistic heritage is an essential undertaking because so much of the world's cultural heritage lies in inhabited places.

Jeffrey Levin
Editor
Conservation, The GCI Newsletter


The Historic City of Quito
by Neville Agnew

Conservation image
Conservation image

In the historic center of Quito, Ecuador, an area of less than one square kilometer, there exist some 18 churches, convents, and cloisters; 25 major public buildings; 12 houses of prime historic importance; several theaters; 6 museums; and over 20 places of general interest, including Plaza Grande, Plaza de San Francisco, and Plaza de Santo Domingo. The city, founded in 1534—a scant 42 years after the arrival of Columbus in the New World—is a repository of immense importance containing paintings and sculpture, archives of historical documents and religious material, and Inca archaeological artifacts and treasures. Because of its extraordinary patrimony, Quito was declared a World Heritage Site by UNESCO in 1978.

Though much has already been done by the authorities in Quito, virtually all the historic buildings and artifacts within the city's center are in need of care and conservation. To these conservation needs must be added the legitimate aspirations of the city's inhabitants for adequate housing, work security, safety, income, and access to consumer goods. With substantial migration from rural areas to urban Quito, the strain on infrastructure and housing has become intolerable, and property owners in the historic center have moved north to new developments in the city. The historic properties these absentee landlords own have been rented out and allowed to lapse into varying degrees of decay.

Despite local and international recognition of the city's historic significance, the pressures of modern urban life continue to take their toll. Overpopulation and traffic, combined with a lack of infrastructure for tourism and insufficient social services, have resulted in a decline in quality of life in the historic center. Other factors contributing to this decline include a 1987 earthquake that severely damaged buildings in the historic district, many of which remain unrepaired. Poor air quality, due to the incomplete combustion of gasoline at Quito's high altitude and lead in the gasoline—as well as traffic congestion and the absence of vehicle emissions regulations—has added to the deterioration of historic buildings.

The Municipality of Quito is playing a leading role in rehabilitation, in part through municipal legislation. The Fondo de Salvamento, a public agency, is working with Municipal Planning Office specialists responsible for management, planning, and public awareness. Supported by present and former mayors of Quito, essential steps are being implemented.

Following a GCI cosponsored Quito conference in 1990 on the conservation of historic cities, the Institute in 1991 joined with the Municipality and the nonprofit Caspicara Foundation to assist preservation in the historic center. Activities included a photogrammetric study of historic buildings on the principal thoroughfare, García Moreno Street; investigation of the color history of building facades; a study of construction systems of buildings; preparation of architectural drawings; and construction of a scale model of the street.

The Institute also undertook climatic monitoring to understand the relationship between meteorological conditions and the dissipation of traffic pollutants, provided conservation advice on gilding and polychrome sculpture for the church of La Compañia de Jesús, and organized an international colloquium on the seismic retrofitting of historic buildings. Conservation, cataloguing, and training in library management were undertaken at the monastery of La Merced jointly by the Institute and the Getty Center for the History of Art and the Humanities, and the Getty Grant Program has provided funding for earthquake-damage repair of La Merced church. To promote preservation awareness and support, a public opinion survey was undertaken, a color poster showing how a rehabilitated García Moreno would appear was distributed, and a 30-minute video on the historic center was produced.

In mid-1994, a full report on the Institute's work in Quito was presented to Mayor Jamil Mahuad Witt.

Neville Agnew
Associate Director, Programs


Seismic Stabilization of Historic Structures
by William S. Ginell

Conservation image

California and the Balkans are two areas where earthquakes pose substantial threats to both life safety and the survival of historically and culturally significant buildings. In California, only a fraction of the adobe buildings originally constructed during the Spanish colonial period have survived. Missions, presidios, and residences have either been destroyed or so extensively reconstructed that features ranging from elaborately decorated interiors to wall paintings by Native American neophytes have been lost forever. Similarly, in the Former Yugoslav Republic of Macedonia, Byzantine churches dating from the 9th to the 14th centuries have been subjected to devastating earthquakes that have toppled towers and domes and, in many cases, destroyed fresco paintings that adorned interior walls. The fact that many of these churches still exist results from their construction design, which imparts some flexibility to the stone, brick, timber, and lime mortar structures.

A large number of these historic structures are still in use, and the problem of ensuring life safety and building integrity without compromising historic values has been of ongoing interest at the GCI for the past five years. Two seismic retrofitting design projects have been in progress—one dealing with American adobes, the other with Byzantine churches.

Seismic retrofitting is the term used to describe building modifications intended to prevent catastrophic structural failure and ensure the survival of occupants. With historic buildings, it is important that retrofitting be designed to minimize intervention and to preserve as many authentic features as possible.

Unlike wood, steel, or concrete structures, thick-walled adobe buildings can crack without necessarily losing their ability to remain standing. Accordingly, the GCI's adobe retrofitting project adopted an approach aimed at improving stability rather than strength. Methods were devised that would be minimally invasive but still prevent wall overturning and roof collapse, the two principal catastrophic damage modes. The methods employed thin vertical and horizontal cord straps and ties, wall center-cores, and continuity provisions that tied the roof to the walls. To test their effectiveness, 1:5 scale model adobe buildings were constructed and subjected to simulated earthquakes on a computer-controlled shaking table at Stanford University in California. The test results confirmed the ability of these simple measures to confine damage to easily repairable, nonstructural cracking. Final tests of a 1:2 large-scale model are currently being performed on a large shaking table to evaluate gravity loading effects that could not be simulated on the smaller models. The results of these studies will be made available in the form of the upcoming GCI publication Guidelines for Seismic Stabilization of Historic Adobe Structures.

For the project on seismic retrofitting of Byzantine churches, a different approach was taken. An actual church, St. Nikita, near Skopje, was selected as a prototype and its dynamic response behavior determined experimentally. An assessment of the most likely earthquake risk was made based on soil conditions and the region's history of seismic activity. A 1:2.75 scale model of the church (weighing 21 tons) was built with local materials; using a shaking table, the model was then subjected to several possible earthquake spectra until structural damage occurred. After being repaired and retrofitted with horizontal and vertical steel ties placed within the walls, the model was shaken again. The retrofitting greatly increased strength to the point that the model was able to withstand a very severe earthquake without significant structural damage.

The methodology developed in this project is generally applicable to similar structures throughout the Balkans, the eastern Mediterranean, and Central Asia. Both the adobe and Byzantine church studies demonstrate that seismic stabilization methods for historic structures can be devised that are effective and considerate of the cultural values inherent in these irreplaceable buildings.

William S. Ginell
Head, Monuments and Sites, Scientific Program


The St. Vitus Mosaic
by Dusan Stulik

Conservation image

The Last Judgment mosaic on the Golden Gate of St. Vitus Cathedral in Prague Castle is considered the most important monumental medieval mosaic north of the Alps. It was completed in 1371 at the request of Charles IV, king of Bohemia and Holy Roman Emperor, who during his reign made Prague the empire's center of power, religion, and knowledge—as well as a place of splendor.

Facing the Royal Palace, the mosaic encompasses 84 square meters (904 square feet) and depicts the Last Judgment in triptych form. At its center is Christ surrounded by angels and apostles. Kneeling beneath are six saints of Bohemia, and below them are portraits of Charles IV and his fourth wife, Elizabeth of Pomerania. On the triptych's two side panels are depicted heaven and hell. Thirty-one shades of colored glass, plus gilded tesserae, can be found in the approximately one million glass pieces that compose the mosaic.

The mosaic's glass is different from the glass typically used by mosaic artists in Italy. In Central Europe the soda needed for glassmaking was not readily available, so glassmakers used potash (potassium carbonate) extracted from the ash of burned wood. Because potassium glass is less stable than sodium-based glass, the St. Vitus mosaic started to fade under a layer of corrosion products soon after completion. Several attempts were made to revive the mosaic, the first as early as the 15th century. In 1619 the mosaic was plastered over, only to be cleaned again in 1621. Despite restoration efforts in the 19th century, by 1890 the mosaic's deterioration was so severe that it was removed for restoration. Then, without any protective coating, the mosaic was reinstalled in 1910, and its slow deterioration began anew. Another major restoration was conducted in the late 1950s, but the periodic maintenance requested by the mosaic's restorers was not carried out, and in several years, the corrosion processes advanced so far that today the mosaic is almost invisible.

Since October 1992, the GCI and the Office of the President of the Czech Republic have been collaborating on the conservation of The Last Judgment. The project began with collecting information on the history of the mosaic and its past treatments. Preliminary conservation assessment of the mosaic was done in collaboration with Italian conservators who had previously worked on the St. Vitale mosaics in Ravenna. The Fraunhöfer Institute for Silicate Research in Würzburg, Germany, and the Materials Science Department of ucla are assisting in development of protective coatings for the mosaic. A series of tests in aging and pollutant-exposure chambers are evaluating the long-term stability and required reversibility of coatings systems being considered for the mosaic. Various methods of mosaic cleaning have also been researched. All proposed technological steps and planned interventions are being discussed in detail with an advisory group of leading Czech art historians, historians, and conservators.

While actual treatment of The Last Judgment is anticipated for summer 1997, all parties involved, including the Office of the President, are emphasizing thoroughness over speed. An important facet of the collaboration is to build a team of Czech conservators who will, after completion of the project, continue to monitor and maintain the mosaic.

Dusan Stulik
Head, Analytical Section, Scientific Program


The Siqueiros Mural
by Jeffrey Levin

Conservation image

The only surviving public mural in the United States painted by the great Mexican muralist David Alfaro Siqueiros is situated on the outside of a second-story wall in downtown Los Angeles. Called América Tropical, the mural has as its centerpiece an Indian crucified on a double cross with an American eagle above it. In the mural's upper right-hand corner are two revolutionary soldiers, one pointing his rifle at the eagle.

Controversial from the day it was unveiled in October 1932, a third of the 24.0 by 5.5 meter mural was painted over shortly after its completion. Some years later, the entire mural was covered with white paint. Subjected to the damaging effects of sun, rain, smog, and earthquakes, the painting began to deteriorate as the white paint covering the mural slowly eroded. The mural faded and in places peeled. In addition, portions of the plaster started detaching from the wall, and the mural's surface, subjected to atmospheric pollution, became coated in dirt.

In 1988 the GCI joined with El Pueblo Park and the Friends of the Arts of Mexico Foundation to preserve what remained of the mural and, after consultation with conservators and engineers, developed a comprehensive preservation program for América Tropical. The first phase began in 1990 when a conservation team spent several months removing the remaining white paint from the mural, cleaning and consolidating the painting layer, and reattaching the detached cement plaster to the brick wall. Traces of asphalt running along the base of the painting were also eliminated.

For over a year and a half beginning in May 1991, an Institute-installed environmental monitoring station adjacent to the mural collected data that provided valuable information about environmental conditions to help guide the designing of a protective shelter. Then, in spring 1994, an on-site digital imaging system designed at the Institute was used by staff to capture and store on computer detailed, high-resolution images of the entire mural. The information will assist in América Tropical's documentation and final conservation, and in the creation of a public exhibition adjacent to the mural.

A primary goal of the project has been to provide public access to the mural. The initial step in that process was the seismic stabilization of the building on which the mural is painted, as well as the stabilization of adjacent buildings, both of which projects were undertaken by the city of Los Angeles. In addition, the Institute, together with other organizations, will be reaching out to the public and private sectors to underwrite the cost of constructing a permanent mural shelter, a public viewing platform, and a historical information area for visitors.

Once a permanent mural shelter is installed, phase two of América Tropical's conservation will proceed. This will include cleaning, stabilization, consolidation, and aesthetic reintegration—i.e., limited inpainting in areas of defined loss to the painting layer. Because of the problematic nature of the materials used in its creation, combined with years of neglect, the Siqueiros masterpiece can never be returned to anything close to its original condition. However, even in its present faded state, the work's artistic power remains. Conserving the mural and presenting it to the public offer an important opportunity to explore questions of political controversy and artistic expression—questions still debated today.

Jeffrey Levin
Editor
Conservation, The GCI Newsletter


The Bas-Reliefs of the Royal Palaces of Abomey
by Leslie Rainer and Francesca Piqué

Conservation image

The most famous and historically significant site in the West African Republic of Benin is a complex of earthen structures known as the Royal Palaces of Abomey. It is there that the Benin government and the Getty Conservation Institute are collaborating on the study and conservation of 50 polychrome earthen bas-relief panels that were removed several years ago from a palace building now known as the Salle des Bijoux (Hall of the Jewels), constructed by King Glélé (1858-1889).

The Kingdom of Dahomey (today Benin) was founded in 1625 by the Fon people and for centuries was a powerful and prosperous center of culture and trade, including the slave trade. The first royal palace in Abomey, the kingdom's capital, was constructed in 1645. Thereafter, each king built his palace near that of his predecessor. Today, the restored 19th-century palaces of King Guezo and King Glélé form the Musée Historique d'Abomey. In 1982 the site was inscribed on UNESCO's World Heritage List.

Earthen bas-reliefs were an integral decorative feature of the palaces. Their function was to represent the significant events in the evolution of the Fon and their domination over a vast territory. The Salle des Bijoux bas-reliefs are particularly important because they are thought to be the last remaining original bas-reliefs from the Royal Palaces (all the other palace buildings have been recently reconstructed). Measuring approximately one meter by one meter, these bas-reliefs depict human and animal figures in allegorical scenes and collectively convey the Fon's complex mythology, customs, and rituals. They provide an invaluable artistic and historic record of Benin's rich cultural heritage.

Since 1993 an international team of wall paintings conservators, museum specialists, and scientists, including staff of the Getty Conservation Institute and the Benin Ministry of Culture, have been addressing the problems afflicting the bas-reliefs. Exposure to extreme weather conditions and termite and insect attacks caused serious erosion and deterioration of the bas-reliefs while they were on the facade of the Salle des Bijoux. Over the years they were repaired and repainted. In 1988 they were removed from the building's walls and framed in heavy cement-stabilized earthen casings. Since then, the Salle des Bijoux itself has been torn down and is being reconstructed. The 50 surviving bas-relief panels remain in fragile condition and vulnerable to mechanical damage when moved.

After reviewing existing documentation on the bas-reliefs' history and condition, and after studying their material composition and causes of deterioration, the project team developed and implemented a conservation treatment plan that includes written, graphic, and photographic recording of the condition of each bas-relief and the treatment carried out. Conservation includes emergency treatment, consolidation of the earthen support and of the paint layer, reattachment of fragments and paint flakes, cleaning, and reintegration in a treatment of minimal intervention. The project's final phase will involve planning of a maintenance and monitoring program to ensure the bas-reliefs' long-term survival and the design of a permanent exhibit. On-site training of Benin Ministry of Culture staff in the conservation, care, and maintenance of the bas-reliefs is an important part of the project, which is expected to be completed by spring 1997.

Leslie Rainer
Senior Research Fellow, Special Projects
and
Francesca Piqué
Research Fellow, Special Projects