University News

Let history breathe: UVA masons are preserving the pillars of the past

Historic masons are going back in time at Pavilion I in the University of Virginia’s Academical Village.

They have carefully stripped away layers of cement that have been slathered onto the historic columns over the years, exposing some of the original Jeffersonian brick.

When first built, the brick-cored columns were covered with a sand/lime mixture. However, over the years, as some of the lime render failed, subsequent generations of masons switched to cement as an outer covering for the columns.

That move proved to be to their detriment.

“The cement has about zero breathability,” historic mason supervisor Matt Proffitt said. “At the time it was introduced, it was the latest, greatest thing that could happen for masonry. It was harder, it was durable, but nobody knew what it would do to the original mortars.”

Robby Kolb mixing lime render to restore columns on UVA Pavillion 1

Historic mason Robby Kolb cleans his tools after applying lime render to a column. (Photo by Lathan Goumas, University Communications)

The cement was hard. The less strong lime render, however, breathed, allowing moisture to escape from the columns’ interiors. Now that moisture was trapped.

“The lime prohibits mold growth,” Proffit said, but “the cement traps the moisture in the column, and the moisture keeps working and keeps deteriorating the lime mortar between the bricks.”

Proffitt said the bricks themselves have not been damaged, though some of the mortar between them had deteriorated.

“A little bit of the original render is very brittle,” Proffitt said. “A lot of it has delaminated from the brick, and to save that, we’ll make a lime mixture in a sprayer and try to drive it into the old render. Hopefully, it will get in there and reactivate that old lime mortar and make it actually adhere back to the brick.”

Pavilion I’s columns are in good shape because not all of the original lime render was removed.

“These columns are some of the best-case scenarios, because they did not take all the original render off,” Proffitt said. “They just scraped it down and actually went on top of the original render. Now, if they had gone back to the brick, it would have destroyed the brick, for sure, but this is the best-case scenario that we could come across.”

The historic masons are removing the cement, leaving the old lime and applying a new lime that is close in composition to the original.

“It’s very close,” Proffitt said. “We’ll take samples from the old render and break that down to where it’s just sand left, and I’ll run that through a sieve. We have a catalog of all the different sands that we use. And I’ll try to find the sand that’s as close as I can.”

Brent Ryder removing paint layers from column capitals and bases on UVA Pavilion 1

Brent Ryder uses a calcium carbonate mixture to remove layers of paint from the column capitals and bases. That allows them to breathe, preventing the stone from freezing and cracking. (Photo by Matt Riley, University Communications)

In making the new render, the masons use a natural hydraulic lime that dries quicker than the original render.

“A hydraulic lime can set when it first gets wet, and when you mix it, it starts setting at that time,” Proffitt said. “But it’s no different as far as strength and breathability and flex and everything as the old lime.”

The columns are part of the original historic fabric of Pavilion I. Proffitt, who has been a mason for about 20 years, appreciates the work of the craftsmen who went before him, and he said they understood the importance of the lime render on the columns.

“They knew about the breathability and the attributes of lime mortar, what it could do to kill mildew and mold,” Proffitt said. “A lot of the bricks are carved into the shape of the round column. Some columns, even some of the Tuscan columns, have pie-shaped brick in there going to the center.”

Similar column work has been completed on pavilions III, IX and X.