By Françoise Descamps, Valerie Dorge, and Giora Solar

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In the small town of Yanhuitlán, Oaxaca, can be found one of Mexico's finest examples of colonial art. The main retablo, or altarpiece, of the Church of Santo Domingo, located in the church's apse, is composed of 11 large panel paintings and several smaller paintings, as well as 16 large sculptures in a wooden frame. The architecture of the frame consists of structural and decorative elements that are carved and gilded or painted. Substantial in size, the retablo is 9 meters wide and nearly 20 meters high.

The town of Yanhuitlán is in a region of frequent seismic activity, and the structural stability of the retablo has been a problem. Previous interventions, such as the addition of steel tensors, wooden supports and sundry cords, wires, and nails, are evidence that the stability of the retablo was a concern in the past. In approximately 1974, an extensive intervention was carried out to stabilize the altarpiece; it involved the building of a supporting steel structure behind the retablo. Most of the accessible pieces of the retablo frame are anchored to the steel structure.

Several years ago, the Yanhuitlán community, worried about the state of this important part of their heritage, requested that the GCI undertake the conservation and restoration of the altarpiece. A partnership was subsequently developed with the Instituto Nacional de Antropología e Historia (INAH), the institution responsible for Mexico's national cultural heritage, and INAH incorporated the retablo project into its overall social and economic development and cultural plan for Yanhuitlán. Additional funds for the project came from a Los Angeles-based private group, Friends of Heritage Preservation, which supports preservation projects worldwide.

The project provides an opportunity to develop a model that can be applied in the many similar situations that involve preservation of retablos in seismic zones. The community has played an active role in the project through the collaboration of its representatives. The project has also included training for conservation students and for community members who will be responsible for the long-term maintenance and security of the altarpieces in the church.

The retablo has an unusual and complex plan to accommodate the shape of the apse and is not anchored to the apse wall. First constructed around 1570, the retablo underwent stylistic changes from Renaissance to Baroque in the early 18th century; according to historic sources, the original paintings and sculptures were retained.

The main retablo, as well as the numerous art objects still remaining in the church, are testimony to the importance of Yanhuitlán since the 16th century, when Dominican priests established a number of major churches and monasteries in the region. The panel paintings are attributed to the artist Andres de la Concha, who was brought from Spain to work on this retablo and others in the Oaxaca area. The altarpiece is significant not only for its artistic and aesthetic qualities but also because it serves as a historical record of retablo construction materials and techniques. Besides the stylistic changes made in the 18th century and a few other minor changes—such as the replacement of some carved sections with pieces taken from lateral altarpieces in the church (a common local practice) and the loss of one painting during a 1977 looting—this exceptional retablo is remarkably intact compared with other retablos. It appears to have escaped the fate of some early altarpieces—that of being dismantled and subsequently reassembled in the intervening centuries, often with replacement elements.

Considering its 400 years of existence in a major seismic zone, it is not surprising that the physical condition of the retablo requires intervention. The wooden framework is weak, with fractures in a number of elements, causing a general load unevenness. Although the new steel structure has supported the retablo, its long-term effectiveness is a concern.

The retablo also remains highly important to the citizens of Yanhuitlán, for whom the Church of Santo Domingo continues to function as a significant focus of community life—and not only for those still there. Former community members, today spread throughout Mexico and the United States, often return for religious ceremonies at the church.

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The first step in the project was to study the structure of the retablo and to analyze its deformations, past interventions, and current condition. At the same time, archival and bibliographical research continued to augment the considerable amount of information already gathered by INAH. A documentation process was also established to identify the specific problems and condition of each component and to organize the information in a format that would accommodate general and detailed analyses and facilitate a comprehensive understanding of the retablo's condition. The documentation combined written, graphic, and photographic formats, and a database was developed to manage and manipulate the extensive amount of information generated. The documentation of the state of the retablo is now detailed and comprehensive (see Harnessing Digital Technology for Conservation Documentation).

From the start of the project, it was apparent that the main problems of the retablo were its structural stability as well as the conservation of its elements. Prior to the condition assessment, it was not possible to define the causes of its apparent structural instability. Theoretically, it could be the result of several different causes or a combination of them. Wood decay, historic changes in the retablo that have weakened its structural capacity, or hundreds of minor and major earthquakes over time could all have played a role.

Since traditional conservation allows for dismantling and reassembling altarpieces that have serious problems, it was assumed that this approach might be taken with Yanhuitlán's main retablo if no other solution could be found. (A preliminary conservation study, carried out prior to the project, recommended dismantling the retablo for conservation.)

The other major step, therefore, was an in-depth engineering study by a structural engineering team consisting of a European firm, internationally renowned for its work in the stabilization of historical structures in different countries, and a Mexican firm. The study of the retablo's structural system, from its original state to its current condition, addressed four main questions:

  • What was the original resistance capacity of the retablo in normal situations and in the event of an earthquake?
  • Was it possible to restore the retablo to its original stability?
  • Was the current steel structure, dating from 1974, sufficiently resilient to withstand any stress in supporting the retablo?
  • Could the retablo be conserved in situ (i.e., without disassembly)?

After investigation and analysis, the structural engineers reported that it was difficult to ascertain the retablo's original capacity to withstand seismic activity. They did estimate that the retablo had been able to carry its own load but that its design was unsuitable for resisting the effects of a prolonged or intense earthquake. The steel structure had been efficient in its supporting role until now; however, in the retablo's current state, deformations and damage indicated that it had reached the limits of its structural stability. It was likely that the weakening and deformation of the wood would continue to shift more load onto the steel structure.

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The data collected in the condition survey provided the information necessary for assessing each component of the retablo—the paintings and sculptures, as well as the carved and gilded or painted elements of the wood frame and its building system.

Based on their experience, some conservators on the project team felt that local conditions would not allow for the use of materials and methods that might be required for in situ conservation of the panel paintings. However, other project conservators believed that while the conservation in situ of the paintings would present some challenges, it could be successfully carried out. While deformations and misalignment in the wooden framework could be only minimally corrected in situ, the applied decorative elements could be realigned and secured in their proper locations, thus restoring to a significant degree the retablo's aesthetic quality. Due to the excellent quality and condition of the gilded and painted wooden surfaces, only a gentle cleaning and minor consolidation were believed necessary.

In their assessment of the altarpiece in Yanhuitlán, the structural engineers reported that the retablo could be consolidated and secured without its being dismantled. They went on to state that disassembly of the retablo posed major risks—a concern shared by some on the conservation team. This assessment was accompanied by a preliminary structural consolidation solution that was later developed into a detailed plan. The plan was based on strengthening the existing metal support by adding elements and new foundations. The proposal did not exclude the possible need to dismantle or replace minor pieces.

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Another issue—whether the panel paintings could be conserved in situ or should be removed for treatment—also received a structural appraisal. The panels play an important role in the structural stability of the retablo, serving as diagonal components in the structural system. One painting could be removed if necessary, and a temporary wooden frame could be inserted in its place. Removal of most of the paintings, however, would potentially require total dismantling.

At this moment, the Yanhuitlán project team is grappling with the decision as to which conservation approach is both technically wise and best preserves the values inherent in the retablo.

The considerations for in situ conservation hold that this is the most appropriate way to preserve the retablo's artistic and historic values, as well as the authenticity of most of its original parts, including the assembly techniques and details. It also avoids the potential for damage that can occur during disassembly, storage and treatment, and reassembly. With in situ conservation, the religious significance of the retablo—still in constant use as the main altar of the church—would also be fully respected. While this approach would entail some aesthetic compromise, the altarpiece would be structurally stable and significantly conserved, and it would continue to reflect its history of four centuries as an important part of the cultural heritage of the community.

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The case against conservation in situ recognizes the historical and technical values of the retablo but holds its aesthetic value as so significant that even if the retablo can be structurally secured in situ, it is important to reestablish its original visual aspect. This means dismantling the retablo, conserving damaged wooden parts or replacing those that cannot be repaired, reconstructing the original structural system, removing the panel paintings to perform a conservation treatment that best reinstates their full aesthetic value, and reassembling the altarpiece.

The case for disassembly holds that because the retablo's original structural system had worked well in this seismically active area for a very long time, the stability of the retablo is best served by correcting its existing structural deformations and designing and installing a new support structure that better conforms with the original materials of the retablo and protects it during future earthquakes. It is argued that this approach considers the aesthetic, historic, and religious values of the altarpiece.

The argument against disassembly is that while this approach maintains the religious significance of the retablo and strengthens its aesthetic value, authenticity and some historic values would be greatly compromised.

From the beginning of the project, the desire of the Yanhuitlán community has been to maintain the beauty of the retablo and to secure it structurally. From the community's standpoint, the appropriateness of in situ conservation or dismantlement remains an issue for professionals to discuss and resolve, as long as the religious and cultural significance of the retablo is respected. The people of Yanhuitlán have worked closely with the conservation team, and they continue to be eager to participate fully in the effort to preserve and maintain a treasured and revered part of their community.

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The Yanhuitlán project has already produced extensive documentation and structural analysis that contribute to our understanding of the architecture, materials, and construction methods of colonial retablos in Mexico. It is expected that as the conservation team works through the question of whether to dismantle or conserve in situ the Yanhuitlán retablo, the project will prove valuable in stimulating and guiding greater exploration of ways to preserve these remarkable elements of our cultural heritage.

Françoise Descamps is a GCI senior project specialist; Valerie Dorge is a GCI project specialist; and Giora Solar is the GCI's group director of Conservation.

Instituto Nacional de Anthropología e Historia

Coordinación Nacional de Restauración del Patrimonio Cultural
Luciano Cedillo Alvarez
Luz de Lourdes Herbert Pesquera
Javier Salazar Herrera
Blanca Noval Vilar
Valerie Magar

Jaime Cama Villafranca
Gabriela García Lascurain
Ruben Rocha Martinez
Alfonso Hueytlet
Sergio Zaldivar Guerra
(Dirección General de Sitios y Monumentos del Patrimonio Cultural)

Contract Conservators
Armando Ugalde Romo
José Carmen Castillo Oveliz

Yanhuitlán Community

Yolanda Martínez Sanchez
Daniel Gonsález Espinoza
Lucila Ramos Cruz

The Getty Trust

The Getty Conservation Institute
Lori Anglin
Françoise Descamps
Valerie Dorge
Rand Eppich
Angela Escobar
Christopher Gray
Irene Sen
Giora Solar
Dusan Stulik

The J. Paul Getty Museum
Brian Considine
Joe Godla
Andrea Rothe

GCI Consultants
Field Architect: Ignacio Moreno
Facilitator: Rosalia Navarro
Structural Engineers: Fritz Wenzel, Bernd Frese, Thomas Halder
(Büro für Baukonstruktionen, Karlsruhe); Javier Alonso, Eduardo Miranda
(Alonso & Miranda, S.C., Mexico City)

Agnes Ballestrem (Central Research Laboratory for Objects of Art and Science, Amsterdam)
Jean-Albert Glatigny (Institut Royal du Patrimoine Artistique, Brussels)