PHILADELPHIA (KYW Newsradio) — National Historic Marker Day is the last Friday in April, and to coincide with that, a historic church in South Philadelphia is holding a gravestone cleaning event to celebrate and preserve history.
Gloria Dei (Old Swedes’) Church, near Front and Christian streets, was established in 1677, making it the oldest Church in the city and the state. There are hundreds of gravestones on the grounds. Among the interned are composers, ornithologists, war veterans, and those who were instrumental in forming the country.
Marco Federico of the Heritage Conservation Collective has extensive experience preserving historic buildings in the city, including City Hall and Eastern State Penitentiary. He demonstrated to volunteers how to clean the gravestones to effectively remove things like algae or moss, which could accelerate stone decay. The process involves using biocide, soapy water, and a soft brush.
"All of these little pores on the stone create a very hospitable environment for microbes," he said.
Many of the stones date back to the 1600s, 1700s, and 1800s.
"When you got bio growth all over certain parts of the stone, what you are doing is that you are creating all of these micro-climates, and that really can accelerate stone decay,” he said.
“And so with this very simple process of cleaning the gravestone, we can really help mitigate that and increase the service life of these historic stones.”
Organizers hope to clean 50 to 100 stones, depending on how many volunteers turn out.
The event will be held on April 25 from 1 p.m. to 3 p.m.
If you would like to help, you can pre-register at www.preserveoldswedes.org.