Behind-the-scenes look at restoration of US capitol’s dome


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WEST JORDAN — A West Jordan company was selected to do the cast iron work for a restoration project of the U.S. Capitol building’s dome, and Tuesday, they gave an inside look into the intricate process.

The Architect of the Capitol organization was founded in 1793 as a way to preserve and maintain the buildings and 553 acres of land on Capitol Hill, according to the organization’s website. The last restoration of the capitol building’s dome occurred from 1959-1960 and the dome was again in need of repairs recently, prompting the current Dome Restoration Project, according to Architect of the Capitol project construction manager Joe Abriatis.

Cast iron was patented as a building material in 1850 and much of the U.S. Capitol building was built out of cast iron in the 1850s and 1860s, according to Historical Arts and Casting Inc. vice president of operations Robert Baird. Water and moisture caused the cast iron on the capitol’s dome to rust, which causes the metal to expand, resulting in cracks and breaks, Baird said.

West Jordan-based company Historical Arts and Casting was founded in 1973 and is one of the only companies in the U.S. to specialize in cast-iron work ranging from the 1860s to the 1940s, Baird said. They were contracted in November 2013 to do the restorative work on the dome.

“After spending my whole life working on cast iron buildings, it’s an honor. It’s the nation’s capitol!” Baird said.

Dozens of decorative pieces, gutters and a balustrade on the tholos level of the dome are being replaced or repaired during the Dome Restoration Project. The original pieces were shipped to the Historical Arts and Casting foundry in West Jordan from Washington D.C., according to Historical Arts and Casting project manager Steve Brown. The parts are meticulously documented with photographs and drawings to ensure they go back to the exact location on the dome once they have been recreated, Brown said.

Decorative pieces from the U.S. Capitol Building dome that will be recreated by the Historical Arts & Casting foundry. (Photo: Faith Heaton Jolley/KSL)
Decorative pieces from the U.S. Capitol Building dome that will be recreated by the Historical Arts & Casting foundry. (Photo: Faith Heaton Jolley/KSL)

The West Jordan foundry will re-use the original metal when possible and the pieces will be recreated as exact replicas of the originals. Brown said 12 layers of paint must be removed from the pieces before they can be molded.

The Historical Arts and Casting foundry will recreate 24 outside gutters, six to 12 inside gutters, a balustrade and just under 100 decorative pieces, Abriatis said. The foundry is expected to be done with their cast-iron restorative work by the end of 2015 and Abriatis said the total exterior work on the dome is now halfway complete.

In the foundry, artisans take the original cast-iron piece and make a rubber mold of it. Then they use that mold to create a pattern of the piece, Brown said. Once they have a pattern, they use it to make another mold using a specialized sand that hardens and creates an impression of the piece. Molten cast iron, heated above 2,500 degrees, is then poured into the impression, creating a replica of the original. The rubber molds can be reused many times, but the sand molds can only be used once, Brown said.

Because cast iron shrinks an ⅛ of an inch per foot after it cools, the molds have to be created a little larger than the original piece so the new piece will end up the same size as the original, Brown said.

“It’s marrying old craftsmanship with new technology,” he said. “Preservation is not an exact science.”

Cast iron is a very heavy material, on average weighing 450 pounds a cubic foot, and the gutters each weigh over 350 pounds, Brown said.

After the pieces are complete, they will be treated with an anti-rust primer before they are painted dome white and shipped back to the capitol building, where they are reinstalled.

Historical Arts and Casting has done cast iron work for other restoration projects including the ZCMI in Salt Lake City and the Grand Opera House in Bloomington, Delaware, Baird said. The company has also created decorative cast iron pieces for several LDS temples including the Payson Utah Temple and the Philadelphia Pennsylvania Temple.

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Faith Heaton Jolley

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