AIC's 44th Annual Meeting

Located near Tucson, Arizona, the Mission San José de Tumacácori is a Spanish Colonial mission and the primary landmark of significance within the Tumacácori National Historical Park. Begun around 1800 and acquired by the National Park Service as a half-completed ruin in 1916, successive campaigns of repair have stabilized but also obscured much of the original surfaces of its once brilliantly painted church façade. With the support of the National Park Service, Penn’s Architectural Conservation Laboratory is currently examining the original façade through thesis work that encompasses archival research, comparative studies, in-situ investigation, laboratory analysis (optical microscopy, fluorescence microscopy, SEM-EDS, instrumental analysis, and gravimetric analysis), and conditions assessment. 

Through the development of North American missions, the Jesuits were decidedly influential in shaping the expansion of New Spain during the colonial drive of the Spanish empire. However after the Jesuit expulsion of 1767, the missions were inherited by the Franciscans, and in 1848 soon entered a period of overall decline until National Park Service superintendent Frank Pinkley initiated preservation in 1918. Pinkley’s interventions thus began a tradition of preservation at Tumacácori that would later guide much of the philosophy and history of architectural conservation in the Southwest. 

Indeed, Tumacácori’s façade can be read as a document in itself that communicates the development of American preservation philosophy for almost 100 years. Originally covered in polychromatic painted lime plaster, significant decorative finishes can be found in protected areas and approximately 155 square feet of historic plaster currently remains on the exterior. Under Pinkley’s stewardship, conservation methodologies were experimental and would eventually give rise to the use of traditional building materials and methods as a form of repair. In contrast, between the 1940s and 1970s, synthetic resins and non-traditional treatments of grouts, water repellents, and consolidants were heavily employed.  By studying the application of these methods in succession, one can gain a perspective of nearly a century’s worth of preservation thinking and insight into the development of architectural conservation and historic preservation in the United States. 

Therefore this analytical work will inform the foundation for a pilot conservation program to conserve the fragile exterior finishes and develop new interpretive content on the design, construction and evolution of the exterior. Furthermore, the project will be highlighted in the National Park Service’s centennial in 2016 by examining the conservation history of Tumacácori’s celebrated church as an illustration of past and present preservation methodologies and site management. Indeed, the façade of the Mission San Jose de Tumacácori represents an exemplary case in which architecture, preservation, and conservation technology converge to reveal the complex history of the church and its present condition – ultimately representing the confluence of Native American, Spanish, Mexican, and Euro-American culture, religion, settlement, and politics.