Of Adobe, Lime and Cement: Preserving the Tumacácori Mission Church, Part I

By Jeremy Moss, National Park Service. Part 1 of 3: the fabric.

The mission church of San José de Tumacácori. Image from the National Park Service's page.

On September 15, 1908, President Theodore Roosevelt used the Antiquities Act to proclaim the Spanish colonial mission church of San José de Tumacácori, in the Santa Cruz River Valley between Tucson and Nogales, a national monument, answering local worry about the church's fate and the looting of antiquities. In 1907 the Tucson Pioneer Historical Society had asked the U.S. Forest Service for help, and Agriculture Secretary James Wilson wrote in February 1908 that the mission deserved protection "from all unseemly exploitation". The NPS took over in 1918; in 1990 the site became a National Historical Park, now 360 acres with a mile of the Santa Cruz River and the missions of Tumacácori, Calabasas and Guevavi. This history marks the centennial theme, "One Hundred Years of Preservation and Stewardship."

Why write preservation histories

Preservation keeps a building in its present condition without major change, protecting its original fabric and the information it holds; restoration returns it to an earlier state, often by rebuilding. Every repair becomes part of a building's history, and recording what was done, and how much original fabric remains, guides future work. Tumacácori, a partly restored ruin, offers nearly 100 years of trial and error in preserving earthen buildings in the Southwest.

A changing philosophy

In the early 1900s historic preservation had no settled philosophy and leaned toward restoration. In 1935 J. H. Tovrea, Tumacácori's first historical architect, argued that the church should regain some of its sense of mystery and sanctity, since its bare interior could pass for a banquet hall, a fort or a storeroom.

Frank "Boss" Pinkley, Tumacácori's first superintendent. Image from the National Park Service's page.

Frank "Boss" Pinkley, the first superintendent, helped set what is now the standard: follow the original construction methods as closely as possible and use the same, "in-kind" materials, working it out by slow experiment, with help from George Roskruge's 1889 photographs of the ruins. By the 1940s restoration had fallen from favour and keeping existing conditions became the aim. From the 1940s to the late 1970s, synthetic and non-traditional materials were used: ethyl silicate and polyvinyl acetate sprays until the 1960s, and Portland cement until the late 1970s. Today NPS policy allows restoration only in certain cases and favours lighter rehabilitation and stabilisation, and preservation and archeology work together, after chances to learn from the ground were lost to poorly documented digging.

The mission's story

Tumacácori belongs to the chain of missions founded by the Jesuit Eusebio Kino across the Pimería Alta, today's southern Arizona and northern Sonora. After Kino's death in 1711 the missions declined; after the Jesuits were expelled in 1767, the Franciscans took over and built larger churches. Tumacácori's church, begun around 1800 and worked on in the 1820s, was abandoned unfinished in 1848. The park also holds the outline of the Jesuit church (1757–1822), convento rooms, the cemetery and mortuary chapel, the irrigation ditch (acequia madre), a lime kiln and the wall of a 4.6-acre orchard and garden.

The mortuary chapel, seen from above. Image from the National Park Service's page.

• The roof went first, through neglect and ranchers taking its beams. Accounts disagree on when: one visitor in 1849 found it nearly intact; an 1858 journal calls the church roofless; two men told Pinkley they saw pine beams in place in 1882 and 1886; none show in the 1889 photographs.
• The 1887 earthquake, about magnitude 7.4 and centred in Sonora, probably opened a large crack in the west interior wall and weakened the facade columns, the pediment and the choir loft.

A ramada at the altar, about 1905. The church is roofless; the rubble in front is the fallen choir loft. Image from the National Park Service's page.

Tumacácori and Casa Grande were the first national monuments protecting historic earthen architecture; Congress's for Casa Grande in 1889 was the first money ever set aside for historic preservation.

Treasure hunters

Rain and wind did damage, but vandals and treasure hunters did worse. For seventy years people dug into the walls and floors after a legendary "lost Tumacácori treasure", and maps to it were sold in Nogales. The first resident superintendent, George Boundey, who arrived in 1929, kept a German police dog to warn of intruders; in 1935 he reported that he and his wife had driven off at least 50 parties of diggers at night in six years. The digging ruined much of the site's buried record.

Saving the fabric

The Forest Service ran the monument until the NPS took it on; a forest inspector in 1907 found the church falling apart, its paintings chipped for souvenirs and its nave covered in visitors' names. Pinkley became custodian on December 9, 1918, and by 1922 cared for 14 southwestern monuments. He hired A. S. Noon, a Nogales contractor and blacksmith, at a day with a starting budget of , used local workers, made adobe bricks to match the originals, and in 1922 won ,000 from Arizona, the first state gift to a particular NPS site, with help also from local groups.

In 1936 Tovrea warned that without measured drawings no one would later know which parts were original. The Historic Sites Act of 1935 and the Historic American Buildings Survey, which drew the church in 1937, answered that need. Charles E. Peterson, a founder of the survey, visited on January 15, 1930, and wrote that the church had served as a bat roost, schoolhouse, bootlegger's den and cow shelter, but was a real treasure deserving great care.

Charles E. Peterson's photograph of the lime kiln, 1930. Image from the National Park Service's page.

Archeology

Archeology here has mostly served preservation, tracing building sequences and exposing features for visitors, yet it has found evidence of 3,500 years of habitation in the valley. Pinkley trenched with picks and shovels; Paul Beaubien (1934–1935) exposed the mission foundations, though treasure hunters had disturbed most of them; Sallie Brewer (1951) found an intact Native American work area; Gordon Vivian (1956) showed the convento room was joined to the sacristy only in the late 1800s or early 1900s; Luis Caywood (1964–1965) exposed the north convento wing, which eroded so fast it was reburied, leaving today's mound. Later work followed the church foundations, the cemetery, a sinkhole that may have been a well (1994), the acequia and orchard wall (2004), and in 2005 the Mendez Homestead, the mission's adobe kiln and a possible cavalry camp with an 1840s scabbard.

Cement, and the return to tradition

The church became a test bed for materials meant to cut maintenance, and some did harm. Portland cement, used as patches up to 11 inches thick and as plaster over most of the original exterior, is less permeable than adobe: it trapped moisture and eroded the walls behind and around it. In 1977 George Chambers began removing non-historic materials and controlling moisture, and since 1978 only traditional lime plaster has been used. Today the church is kept with sun-dried and fired adobe, natural and hydraulic lime, crushed brick and mud mortars, applied by hand.

A preservation crew removing non-historic cement plaster from the church's west exterior, 1978. Image from the National Park Service's page.

The interior plaster and its paint

The interior holds the most original lime plaster, two 1-inch lime layers under a thin gypsum wash, more than 4,000 square feet in the sanctuary and nave as estimated in 1949. Threats include plaster coming away from the wall, birds and bats, and moisture. Synthetic sprays tested over the years made it brittle; nails (1940s) and lag bolts (1972–1973) meant to hold it may have caused more cracks. In 1949 NPS employee Charles Steen and Harvard conservator J. Rutherford Gettens first cleaned the plaster, and conservators worked on the dome from 1979 to 2002.

Gettens analysed the painted plaster:

The binder is unknown; no egg or milk proteins were found, and the gypsum coat over the paint suggests it was not true fresco.

The adobe walls

About 70 percent of the interior adobe is original. Moisture wicks up the walls when the soil beneath passes 15% water, and the church sits across a natural drainage from the Tumacácori Mountains to the Santa Cruz River. Drainage work since the 1950s has cut flooding, but the underground flow toward the west wall is probably the main source of damp in the church and convento walls, a problem worsened by impervious coatings from the late 1920s on.

Continued in Part 2 and Part 3.

Sources

• Jeremy Moss, "Of Adobe, Lime, and Cement: The Preservation History of the San José de Tumacácori Mission Church (Part I – The Fabric)," National Park Service. https://www.nps.gov/articles/preservation-history-of-the-san-jose-de-tumacacori-mission-church.htm
• A 1952 drawing of the sanctuary's north wall by Jimmie Trujillo is not reproduced here.