SLOWLY they're crumbling away - old books: classics, historical documents; our written heritage turning to dust on library shelves across the country. Although help is on the way, it's slow in coming. The disintegration will be continuing for a while.
The betrayer: acid in the paper - aluminum sulfate or alum for short - added to stiffen the paper. Catalyzed by heat, humidity, and air pollution, the alum gradually breaks down the carbon bonds that hold together the cellulose fibers in the paper. Pages become brittle. They're in trouble when they fail the ``two double-fold'' test - when the upper corner of a page tears or cracks when creased back and forth four times. This embrittling can begin to happen in as few as 15 years.
``We are dealing with a mammoth embrittlement problem here at the Harvard Library,'' says Carolyn Clark Morrow, Malloy-Rabinowitz preservation librarian for Harvard University's collection of 11.5 million volumes - second in size only to the United States Library of Congress collection.
Research and university libraries are the hardest hit because they retain so many books and have the oldest collections.
Ms. Morrow estimates that one-fourth to one-third of the books are already brittle, making some unusable. Age is not the most important factor in crumbling paper, she says. The oldest books - those printed before 1840, when paper was made from linen fibers and stiffened with rosin, are in excellent shape.
The problem is also critical at Chicago's Northwestern University library, where Richard Frieder, head of the preservation department, estimates that 30 percent of the 2.5 million volumes are brittle.
At least five processes designed to halt the deterioration of acid paper and protect against future erosion are currently in use. But so far, preservationists are not convinced that any of them offers a solution that is safe, effective, and economical enough to use for all endangered books.
``We're talking enormous amounts of money,'' says Mr. Frieder. He says that to deacidify the books that need it most - at $3 to $10 a volume - would cost $15 million (the entire Northwestern University annual library budget is $9.5 million).
Still, this is less than microfilming at $70 a volume (which is a poor substitute for holding an actual book, he notes) or replacing a book for about $80 a volume (ordering, cataloging, and shelving).
Yet even if libraries had enough money to deacidify their books, Frieder says, no process is completely safe. ``We need more chemical testing on this,'' he says, citing potential hazards of storing treated volumes in a small space where library users might be exposed to residuals from the preservation processes.
Says Frieder: ``We [librarians] have an enormous responsibility.... We've got to be as sure as we can be that the treatment will have the desired result. We can't treat thousands and thousands of books and put them on our shelves, and expose people to them.'' As yet, there isn't an independent agency testing preservation techniques for safety.
Currently two methods of mass deacidification are in use: liquid chemical bath and gas infusion. Only the liquid-bath method - known as Wei T'o - has been widely used. In 1982, the Canadian National Library and National Archives in Ottawa installed a small facility that deacidifies 30,000 new volumes and other items of value each year.
The Wei T'o system, (pronounced way toh, named for the Chinese god who protected books) was developed by Richard Smith, a chemist and librarian in Matteson, Ill. It involves spraying liquefied magnesium carbonate on individual books enclosed in a small chamber. (The chemical preservative is also available in ``soft spray'' cans sold for individual preservation jobs, such as the first copy of the US Constitution and the Gettysburg Address.
But to use the system on a mass scale, a special facility must be built close to where the books are stored.
Librarians are concerned about the process, which uses Freon. These chlorofluorocarbons float into the upper levels of the atmosphere where sunlight converts them into highly reactive chemicals called radicals, which in turn break down ozone. Half the Freon used in this process escapes into the air. (The other half is recycled back into the process.)
In Canada, the Ottawa library's preservation coordinator, Jan Michaels, is pleased with the Wei T'o results. Her only complaint is that not all books can be treated in the liquid process: Certain inks run, plastic bindings aren't acceptable, and large items don't fit into the process chamber.
The gas process has also produced mixed results so far. The Cleveland Public Library shipped 20,000 Russian books to Book Preservation Associates (BPA) in Carteret, N.J., where they were treated by the BPA's gas process for $2.40 a volume. Most books came out fine, but some have since returned to an unacceptable acid level, and several covers stuck together, says Edward Seeley, head of technical services at the library.
Mr. Seeley seems unconcerned about what bothers some other preservationists about the BPA process. The chemical used - ethylene ammonia - is on the Environmental Protection Agency's list of carcinogens.
Meanwhile, the world's biggest customer, the Library of Congress, is trying to find a way to halt the crumbling of some 16 million of its 19 million volumes. The library has been working for 15 years with scientists at Akzo Chemicals in Chicago to come up with a system that is safe, effective, and inexpensive.
The process they have developed uses diethyl zinc - DEZ - in a gas infusion chamber where the books are coated with a thin layer of zinc oxide. Akzo project director Richard Miller claims the DEZ method causes no harmful environmental side effects. And at $6 a volume, it's relatively cheap.
Unfortunately, the system hasn't been used on a mass scale yet, and the only facility is in Texas. The Library of Congress has yet to make a final decision to go ahead.
In the meantime, preservationists are gearing up to get at the root of the acid paper problem by urging publishers to switch to acid-free, ``archival quality'' paper (see related story).
Back at Harvard, Ms. Morrow notes that the invidious disintegration problem is harming more than books. ``It's not just scholarly works that we're interested in,'' she says, but ``posters on the walls, ... stuff tacked up on our bulletin boards.... That's culture, and we need to keep copies of that.''