One-Fourth of 14 Million Volumes Already Damaged : Library of Congress Tries to Neutralize Acids Destroying Valuable Books

The Washington Post

For more than a century, paper manufacturers have inadvertently been planting self-destruct mechanisms in most of the paper used to print books--acids that gradually break down the fibers.

Library of Congress officials say the acids have now damaged an estimated one-quarter of the library’s 14 million books, leaving their pages so weak that they crack when folded. The books can no longer circulate. Every year, 77,000 more books in the collection become equally brittle.

Library officials say that unless the destruction is stopped, 97% of the volumes in the federal government’s premier library--also the world’s largest information storage center--will eventually disintegrate. All other libraries are thought to face the same problem.

Moving Toward Solution


“It’s a very serious problem but, fortunately, we think we’re moving rapidly toward a solution that we think is very promising,” said Peter G. Sparks, director of the library’s Mass Deacidification Program.

Sparks said a method has been developed to neutralize the acid in books. It won’t repair the damage but will stall it for a long time. A book on medium-quality paper that would have disintegrated in 50 years should last, after treatment, between 150 and 250 years. Books on better paper should survive longer.

The acid-paper problem is a result of several manufacturing methods that came into wide use during the 19th Century, when wood replaced rags and linen as the chief source of cellulose fiber. Papers made before then usually last for several centuries, sometimes nearly 1,000 years, and most are in good condition today.

The library’s treatment method is being tested in a small pilot plant in Houston, which handles 350 books at a time. The chemical treatment takes 50 to 55 hours per batch. Sparks said that by early 1991, the library hopes to have a full-scale plant in operation that will process between 4,000 and 9,000 books at once.


Even at that volume, however, it will take 20 years of round-the-clock processing and $100 million to preserve all the library’s holdings.

Encountered Setbacks

That goal, if achieved, will not have been won easily. The library has been working since 1973 to develop a practical preservation method and has encountered major setbacks, including an explosion and fire in 1986 at an earlier test processing facility.

Although at least two other methods of deacidifying books were available, neither met the library’s demand for a process that could handle large numbers of books without damaging the paper, the ink or the glues used in binding.

Unsatisfied with existing methods, the library invented its own, based on diethyl zinc, or DEZ, a chemical used to make plastics.

Early tests showed that DEZ worked beautifully. Books placed in a special treatment chamber readily absorbed DEZ vapors, carrying their acid-neutralizing powers deep inside. While other methods required immersing books in liquid or fanning open their pages to expose them to the chemical, the DEZ process worked on closed books, even on large stacks of books.

And DEZ was not toxic. All it left in the paper was a trace of zinc oxide, the same substance used in ointments for diaper rash and other skin irritations.

Series of Disasters


In December of 1985, however, a nine-week series of disasters began. They involved DEZ’s one big drawback--it burns, almost explosively, if it comes in contact with water or the oxygen in air.

The library had contracted out the development of a pilot plant to the National Aeronautics and Space Administration’s Goddard Space Flight Center in Beltsville, Md. But the first time the process was tested on a batch of books, the treatment chamber exploded, apparently because water got in, and a fire began. The equipment was badly damaged but no one was hurt.

Cleanup and repairs took weeks, as technicians worked carefully to keep the DEZ still in the system from touching air or water. Still there were subsequent fires and explosions.

On Feb. 14, 1986, harried NASA officials--still reeling, some say, from the explosion of the space shuttle Challenger two weeks earlier--gave up and called in an Army demolition team to destroy the plant. Explosive charges ruptured DEZ pipes and 700 pounds of the stuff, 670 pounds more than were supposed to be there, gushed out to feed a conflagration far bigger than anyone expected.

The incident raised major challenges to DEZ on grounds of safety. Congress asked its Office of Technology Assessment to evaluate alternative book preservation methods. Even before the office’s report was in, however, the library, still convinced of DEZ’s advantages, dropped NASA as a contractor and turned to Texas Alkyls Inc., a Houston chemical company with experience making and handling DEZ.

Experience in Process

“They had the skills and experience we needed all along,” Sparks said. “We now have a DEZ facility that’s been operating since last January.”

Sparks said 22 batches of books have been processed at the Houston facility with no mishap.


“I think the safety questions are completely resolved,” Sparks said. “We now know how to use this technology and this material safely. It works very well. And we’re getting ready to scale up to a major facility that will meet our needs and also be able to treat books for other libraries.”

Books to be treated with DEZ are first loaded in crates into an airtight chamber. When the chamber is sealed, vacuum pumps draw out nearly all the air and moisture, including the water normally in the paper itself. Then nitrogen gas is pumped through the chamber to purge the last of the air and water.

Next, DEZ gas is pumped in and held long enough for it to permeate the paper. As the chemical seeps into the paper, it reacts with the acids, neutralizing them. As a result, diethyl zinc molecules break down and recombine with the acid and residual water to make zinc oxide, which stays in the paper, and ethane gas, which seeps out.

Rehydrate to Normal Levels

After a nitrogen gas purge of the ethane, the chamber is filled with water vapor and carbon dioxide gas so the books can rehydrate to normal levels and be removed.

The library is funded by Congress, and the committees with jurisdiction over its budget have required it to invite bids from all suppliers of book preservation technologies.

“We will go through an open bidding process,” Sparks said, “but it’s very hard to imagine that any alternative could look better. We already know very well what they are.”

Although the library once envisioned building its own deacidification facility, it has decided to let private industry build and operate it. The library will offer a $100 million, 20-year contract to assure the winning bidder plenty of business. The winner, widely expected to be Texas Alkyls, will also be allowed to treat books from other libraries.

Sparks said plans call for the facility, which the library would like to be near Wilmington, Del., and its concentration of chemical-handling expertise, to be operational by late 1990 or early 1991. At that point, if all goes as library officials hope, library trucks will begin 20 years of shuttling up and down Interstate 95.