Two alumni from Penn’s School of Design led the restoration of a prominent historical landmark at Christ Church Burial Ground: Benjamin Franklin’s grave marker, where the University’s founder has rested for more than 225 years.

Several years ago, John Hopkins, the tourism and burial ground manager at the Christ Church Preservation Trust, noticed a split in Franklin’s grave marker.

“Franklin’s grave is one of the most important artifacts on our campus,” explains Hopkins, who has worked at Christ Church Burial Ground since 2012. “Over the last few years, [the crack] was getting slightly bigger.”

Hopkins brought it to the attention of John Carr, the owner and principal architectural conservator of Materials Conservation Co., LLC, and senior conservator Marco Federico.

Together, Penn Design grads Carr and Federico form a historical conservation powerhouse, combining the fine-tuned skills of the artisans of yesteryear with modern engineering know-how. They knew restoring the memorial was an interdisciplinary undertaking that Franklin himself would appreciate, as several scientific and engineering factors and techniques went into its preservation for generations to come.

“Franklin wanted a very simple ledger tablet for his grave marker,” Federico says. But, during site improvements, Franklin’s tablet was placed into a granite frame of sorts. Although aesthetically pleasing, scientifically, it was a recipe for disaster.

Marble is a metamorphic rock that needs to “breathe,” whereas granite is an igneous rock that does not let moisture through.

“Marble is soft: it takes on moisture and it’s able to let the moisture evaporate,” Federico explains. “When it’s wet, it expands and needs to dry out to contract.”

Taking into account marble’s expansion and contraction properties, along with the fact that its granite base was unable to drain, intensifying damage was inevitable: Warping occurs when the top of the marble has dried, but the bottom half has not.

“[The tablet] was sitting in this muddy pocket and never drying. The moisture issues were wreaking havoc on the stone itself to the point where this once very small crack began to open up more and more,” Federico says. “If only half the stone is drying out while the bottom continually remains saturated, fatigue failure will eventually occur and it will shear in half.”

If nothing was done, he says the ledger would have broken in half in less than five years.

“We set the plan in motion to redesign it in a sense, so the stone could still be on display for the public, but that it could be able to shed the moisture, dry out and be protected at the same time,” Federico says.

Another source of the damage to Franklin’s marker has been from pennies tossed by tourists onto the grave for luck. Over time, the copper coins have caused divots in the marble—and the damage is irreversible because “there’s no way to treat all of the pitting on the stone,” Federico says.

The surface will continue to weaken, he adds, and if people keep up the well-meaning but ill-informed tradition, water will gather on top of it, slowly contributing to its destruction.

Carr and Federico knew the risk of complete breakage during restoration was a possibility. But Hopkins had faith in their abilities.

“There is no one I trust more with the preservation of the Burial Ground,” Hopkins says.

It was at Penn Design that the team was taught to solve complicated and delicate problems like this one. Federico says it is a natural fit that Penn alumni conducted Franklin’s memorial restoration.

“We are entrusted with some of the country’s most valuable and significant cultural property,” Federico says. “Who else butPenn alumni would be doing something like this? I think it’s perfect.”

Carr moved to Philadelphia 27 years ago to attend Penn Design. A specialist in stone conservation, Carr earned a Master of Science in Historic Preservation. Federico, a native Philadelphian, has areas of expertise in stone and terracotta conservation and also received his master’s in Historic Preservation, in 2008.

“We are the custodians of cultural property,” Carr says. “We are kind of like physicians of three-dimensional objects.”

Carr adds the team’s deep connection to Penn helps strengthen the architectural conservation profession’s goals of sharing research and techniques for everyone’s benefit.

“We all want to get our projects and solutions out there so that others can use them as case studies,” Carr says. “The University of Pennsylvania serves as a clearinghouse of information that we can use to advance the field and do better projects.”

For Franklin’s grave marker, the team took their time: They carefully lifted the ledger, stabilized its bottom with a cement-like material, and installed stainless steel “stitches” to prevent the crevice from widening.

Then, Federico fixed the surface with porous, lime-based mortars that ranged from light to dark gray.

“We matched the composite mortar to the lighter color of the tablet and used a mineral stain to continue any darker striations,” he says. The goal was to “blend those repairs in and make them a little less visible.”

He paid special attention to where the crack ran along the “k” in Franklin.

“I wanted to maintain the integrity of this inscription,” Federico adds, “because as far as we know, those letters are from when they were cut back in 1790.”

Next, they constructed an elevated base with a drainage venue that allows the bottom half of the marble to dry. Now when it rains, the water runs off the side and down its old granite frame, which was installed sometime during the 19th Century, Federico explains. Plus, the new design offers a safety net.

“If moisture does find its way to the inside of the base we constructed, there are weep holes to allow for moisture to come out,” Federico says.

The restoration took approximately six weeks and $80,000 to complete.

The funds came from a variety of sources, including members of the public; Jon Bon Jovi and his wife, Dorothea; the Philadelphia Eagles; and grants from the Pennsylvania Historic and Museum Commission, as well as the Florence Gould Foundation and Penn.

“We didn’t want a brand-new-looking stone; we wanted to conserve the object as it is, and allow this historic resource to have a vastly increased lifespan,” Federico says, estimating that the marker can now likely sustain another century outdoors.

Hopkins says that visitors can barely see the damage now.

“The changes we made were very subtle and in keeping with Franklin’s intentions,” Federico says. “Our greatest compliment oftentimes is: ‘It doesn’t look like you did anything.’”

Photo: A team of Penn Design alumni including Marco Federico of Materials Conservation Co., LLC, spent six weeks conducting a restoration of Benjamin Franklin’s marble grave marker at Christ Church Burial Ground, located at 5th & Arch Streets, Philadelphia.