Starr Herr-Cardillo, Patronato San Xavier’s conservation project manager, points out areas where cement patches were placed for repairs in the 1950s over the original facade at Mission San Xavier.

 Mamta Popat, Arizona Daily Star

Art conservators found something staring back at them when they climbed the scaffolding last month to study the façade of Southern Arizona’s most famous church.

As it turns out, the doomsday mouse at San Xavier del Bac has round, metal nails for eyes.

That was news to Tim Lewis and Matilde Rubio, who have worked on artwork at the mission for decades.

“We never noticed that before,” Lewis said. “That’s what we like about this work: It’s never boring. Even as long as we’ve been doing it, we still get surprised.”

The cement cat on the opposite side of the façade has no such eyes, and maybe we should all be thankful for that. Legend has it that the world will end if the cat ever catches the mouse.

Who gave the mouse its competitive edge and why remains a mystery, though experts believe the round cut nails that were used do not date to the mission’s construction in the late 18th century.

Tiny nails mark the eyes of a cement mouse that perches on the façade of Mission San Xavier: Experts believe the round cut nails do not date to the mission’s construction in the late 18th century, but when and why they were added to the mouse remains a mystery.

Mouse eyes were not the only surprise discovered during a monthlong inspection of the ornate entrance to the more-than-225-year-old building.

Something else they had never previously noticed: “The two lions on either side — one is female and one is male,” Lewis said.

Fellow longtime conservator Matilde Rubio said she was struck by how many of the original pigments — iron-oxide red, ochre yellow, manganese black and white lime wash — can still be found in the nooks and crannies of the façade, including spots that are nearly impossible to see from the ground.

Conservation project manager Starr Herr-Cardillo said she was surprised by how intricate the original detailing work was from close up.

“It was very painterly up there. You can see brushstrokes,” she said. “To think that it’s been up there for 200 plus years in extreme sun, heat, weather and crazy temperature swings — those are pretty harsh conditions for materials, and there’s still so much there.”

Scaffolding at Mission San Xavier was put up as part of the Patronato Conservation Project.

Expert eyes

The recent inspection was organized and paid for by Patronato San Xavier, the nonprofit that has overseen preservation and fundraising for Arizona’s oldest intact European structure since 1978.

Working from scaffolding erected above the entrance to the church in late October, the study team examined every inch of the façade to assess its condition, map its flaws and plan future repairs.

They took photographs with a kind of portable microscope and went up at night so they could scan the molded plaster surface with ultraviolet and infrared light to pick up otherwise invisible details.

The team also studied similar features and restoration efforts at Tumacacori National Historical Park, 45 miles south of Tucson, and the Franciscan missions in the Sierra Gorda region of central Mexico.

Several experts joined the effort along the way, including University of Arizona professor Nancy Odegaard, who is chair of Patronato’s conservation committee and the head of the Preservation Division at the Arizona State Museum.

Frida Itzel Mateos González, a paint and plaster specialist from Mexico’s equivalent to the National Park Service, spent a week up on the scaffolding.

Wood restorer Luke Addington, who has already worked on San Xavier’s altar railing and east doors, came in to examine what’s left of the reconstructed balconies on the front of the church.

And preservation engineer Melvyn Green, who has worked extensively on Spanish missions in Southern California, sized up the structural integrity of the columns running up each side of the façade.

Conservator Frida Itzel Mateos Gonzáles conducts a "cleaning test" by removing 1950s-era cement-based stucco with a dremel.

Concrete concerns

This was Lewis and Rubio’s first in-depth look at the church’s decorative entrance since 2008, when the husband-and-wife conservators wrangled money for a shorter, partial assessment of its condition. The couple has been lobbying for a longer look ever since.

“The façade to me is very significant, because it welcomes the people to come in,” said Lewis, who grew up on the Tohono O’odham Nation and has attended services at San Xavier for much of his life. “You know, we just want to preserve what’s been here for 200 years.”

“I would say (the façade) is probably one of the least understood parts of this building,” Herr-Cardillo said. “Tim and Matilde have identified this as a priority for quite a while now. It’s just been on the waiting list, because there’s so much else.”

Rubio put it another way: “They finally realized that to do the work on the façade, you need conservators,” she said. “It is not a construction project.”

Mission San Xavier was built between 1783 and 1797 with kiln-fired adobe bricks and O’odham labor.

In the centuries since, the structure has been abandoned and restored several times, including an extensive conservation effort in the 1940s and 1950s that saw much of the building coated in concrete plaster made from Portland cement. That included the statues and decorative features of the façade, which were then painted in garish colors that didn’t quite match the earthier tones that had been there before.

A statue of Santa Barbara displays the original hand-painted detailing on the left and right side of her cloak at Mission San Xavier. As part of the Patronato San Xavier conservation project, the last remaining cement-based plaster on the exterior of the East Tower is being replaced with a traditional lime-sand plaster.

It wasn’t until decades later that caretakers discovered the protective plaster was actually damaging the walls and interior.

“The problem with concrete is it’s strong, but it also retains moisture,” Lewis said. “What we’re seeing a lot of is that the original material behind it sort of disintegrates.”

Most of the Portland cement on the exterior of the building has since been removed and replaced with new coats of traditional lime-washed plaster mixed with cactus juice, which allows the walls to breathe and dry out.

When the plaster-replacement work now underway on the east tower wraps up next year, the façade will represent one of the only sizable patches of Portland cement left.

Outreach upfront

Herr-Cardillo said any work there is unlikely to start for at least a year or two. First, they have to compile all the information they gathered over the past month, develop a restoration plan and raise the money they will need to execute it.

“An important part of that process is going to be sharing what we’ve learned widely and doing a lot of community outreach,” she said. “In developing our approach, it needs to be sound from a material standpoint and a conservation standpoint, but also it’s the face of the church. I feel like you need to bring people along with that decision.”

“Especially the community members around here on the reservation,” Lewis added. “This is still a working church. That’s what we have to understand.”

Rubio estimates it could take up to two years to carefully remove the 1950s plaster and recoat parts of the façade with a more traditional white or off-white lime wash similar to what was used in the 18th century.

Conservator Matilde Rubio removes a small sample of original finish for analysis.

There are no plans to repaint the once-colorful entryway beyond that.

Even if they wanted to, Herr-Cardillo said, they simply don’t have enough definitive proof of what it used to look like to try to recreate it. All they have are a few remaining details and a sense of the overall palette.

“The colors actually preserved pretty well,” she said. “We can see them well up there.”

Rubio is eager to get the job started. After 25 years of restoring and protecting the artwork inside Mission San Xavier, she considers the façade the icing on the cake of her career as a conservator.

“It could be maybe the biggest project that I do,” she said.

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Contact reporter Henry Brean at hbrean@tucson.com or 573-4283. On Twitter: @RefriedBrean