AUDIE CORNISH, HOST:
Preservationists try to protect historic papers from decay. Unfortunately, one of their go-to methods undermines those very efforts. Now millions of old documents from presidential papers to personal slave journals are at risk, as South Carolina Public Radio's Cooper McKim reports.
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COOPER MCKIM, BYLINE: On the first floor of South Carolina's state archives, director Eric Emerson walks into a cold, white room. The dehumidifier keeps the mass of old documents from smelling.
ERIC EMERSON: (Laughter) So we try to keep this to be an odor-free zone.
MCKIM: Emerson walks past a row of 10-foot, metal shelves to find the department's crown jewels.
EMERSON: So these are the seven constitutions of the state.
MCKIM: From left to right, the constitutions range from those written during the Revolutionary War all the way through Reconstruction. His colleague Patrick McCawley is worried about them.
PATRICK MCCAWLEY: Some of these documents like this - we really can't put it on display because it's in such poor condition.
MCKIM: McCawley points to South Carolina's first constitution from 1776. It's stiff, stuck together with a plastic outer coating like a restaurant placemat. The other constitutions look the same.
MCCAWLEY: You can see how brown this is coming. This should not normally be this brown.
MCKIM: For 20 years, beginning in the 1950s, the state laminated documents like this to try to protect them from aging. This discoloration is not supposed to be happening. It's caused by a chemical reaction. The natural acids from the paper mix with the plastic to create a noxious vinegar. Each passing year will further degrade the document until it's gone.
MOLLY MCGATH: You're effectively forming an envelope where you're keeping the acids in the paper, not allowing them to migrate out.
MCKIM: That's Molly McGath. She's a researcher at Johns Hopkins University who's written about lamination extensively. South Carolina isn't the only place having problems. McGath says the method was performed around the U.S. and other countries throughout the 20th century. There are as many as 6 million laminated historical documents. She says the method was first popularized as a cheap and easy way to preserve them.
MCGATH: You put plastic on either side. And then you put it through the press. And it's done at the end. So you have a very high throughput.
MCKIM: McGath says some archives laminated 20,000 pages a year. But in the 1960s, curators began to notice problems, the scent of vinegar. After the 1970s, the method ground to a halt. Now states are stuck with slowly degrading documents.
MCGATH: We are sort of fighting a clock.
MCKIM: In Texas, archivists have started scanning their collection, like the 1836 treaty between state commissioners and the Cherokee Indians. In Virginia, the state conservator is choosing to remove the lamination entirely. Leslie Courtois has spent 20 years delaminating thousands of important, old papers.
LESLIE COURTOIS: It's tiring. It's tedious. It's very laborious. It's messy.
MCKIM: Plus, it's expensive and time consuming. Courtois has to place each page of a document in a chemical bath. South Carolina doesn't have all the materials or the staff to do this. So they're seeking $200,000 to have a private lab take it on. For NPR News, I'm Cooper McKim in Columbia.
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