The Munras Murals Conservation Project
The Mission San Miguel Conservation Project is breaking new ground in art and materials conservation as restoration experts create techniques and pioneering technologies to conserve and stabilize the unique adobe structure and interior frescos and decorative finishes inside the mission church.
Ensuring the survival and integrity of Mission San Miguel demands patience. Repairs that might take weeks in a modern buildings require months in older adobe structures. In the past, use of incorrect materials or techniques has resulted in damage to, or even loss of, historical and cultural resource at the missions. Although it may add to the overall costs of stabilization and restoration, careful implementation is necessary for proper preservation results at Mission San Miguel Arcángel. The Munras Murals Conservation Project and the broader preservation project at Mission San Miguel seek to protect this important historic resource based on a thorough understanding of the buildings, minimal intervention, and reversibility.
Stabilization and conservation of the Munras Murals is an important first step in the $6 million project to repair and restore the church at Mission San Miguel. The murals must be secure enough to withstand the vibrations and construction activity required to install seismic reinforcement for the larger adobe structure. A $75,000 grant from the Getty Foundation funded the initial stages of the Munras Murals Conservation Project, including preliminary restoration and conservation studies and a historic structure report for the historic church building to guide future treatments.
Developing the conservation plan for the Munras Murals has taken careful research and documentation by the experts engaged in the project. While the colors of San Miguel's interior frescos and decorative finishes are exceptionally true, their natural pigments are at risk of simply detaching. The pigments and materials used by Munras and the Salinans are rare. Research is helping to identify exactly what flowers and plants were used to make the pigments so they can be duplicated in future conservation efforts. For example, Munras and the Salinan artisans used local materials to produce paints for the murals, including cinnabar from the New Almaden mines near San Jose, and mineral based pigments from Mexico. Some of the paints were made using unusual substances such as cactus juice. Numerous pilot treatments and testing procedures have been necessary to determine the best conservation methods for the paintings. In some cases, Mission San Miguel Arcángel is serving as a laboratory for pioneering techniques, developed by the conservation team and employed for the first time on Mission San Miguel's artwork.
The conservation project will include treatment testing to determine how the pigments and materials used to make the Munras Murals will react to different conservation methods. Conservators will clean the mural surfaces and remove stains, consolidate painted surfaces to prevent additional cracking, fill voids in the plaster behind the murals with injection grouting, and fill cracks and areas of paint loss. As part of this work, the Getty Conservation Institute used special laser technology to detect voids behind the decorative finishes on the mission church walls and to assess the effectiveness of grouting used to reattach loose plaster to the wall. The use of laser technology, a minimally invasive technique, eliminates any disturbance of the painted finishes and protects the fragile murals. The final step in the conservation project will include inpainting of areas of paint loss to match the original surrounding paint schemes.
In addition to the conservation work, innovative technologies are being used to monitor the seismic stability of the Munras Murals. Seismic planning has required complex soils testing, as well as pioneering laboratory simulations of adobe construction. The Network for Earthquake Engineering Simulation at the University of California, Los Angeles, (NEES@UCLA), has been monitoring the impacts of vibration levels from construction activities and earthquakes on the historic decorations on the mission's adobe walls. NEES@UCLA is part of a national network of experimental research equipment sites specializing in field testing and monitoring of structural performance, in this case adobe. Their work will result in recommendations for maximum allowable vibration levels during construction and help contractors determine the safest construction methods. The work NEES@UCLA completes at Mission San Miguel will also contribute to the bank of knowledge on structural engineering and modeling for large adobe structures.
The Project Team
Thirtieth Street Architects, Inc., Newport Beach, CA
Roselund Engineering Co., South San Gabriel, CA
Fred Webster, Ph.D. Associates, Menlo Park, CA
South Coast Fine Arts Conservation Center, Santa Barbara, CA
Robert Hoover, Ph.D., Archaeologist, San Luis Obispo, CA
