SALT LAKE CITY—For books, it's a long, slow journey to yellowing and crumbling. That's because acidic chemicals in most kinds of modern paper slowly break down the cellulose fibers of which books are made. After old books become yellow and start crumbling at the edges, they eventually turn into dust, after several decades.
The Library of Congress and other institutions have long deacidified books to preserve them. But commercially available technologies such as the one the Library of Congress uses change the feel of paper and make it slippery, Piero Baglioni of the University of Florence said here Sunday at the annual meeting of the American Chemical Society. That effect is due to the fluorine-based chemicals—think Teflon, another fluorine-based compound—used to mix deacidification particles with water. “The paper feels different to the touch” after this kind of treatment, Baglioni says.
Enter nanotechnology. Baglioni and his colleagues have a fix: An alcohol-based solution containing 100-nanometer particles that they spread on the pages. The nanoparticles, made of calcium hydroxide or magnesium hydroxide, stick to the cellulose fibers and begin to suck up the protons that hang around and make the paper acidic. Once the fibers are chemically stabilized, the books should last longer, Baglioni said, although it’s hard to know what will happen in the long term: Scientists have a number of ways simulate the effects of aging, but no universally accepted way to predict the success of deacidification.
Baglioni’s nanoparticles don't leave the paper slippery because they're alcohol-based, rather than water-based, and don't require fluorine-based compounds. The Florence team’s technology has been around for several years and has been used to restore ancient books, says Baglioni, who also says restoration experts like it because it doesn’t alter the feel of the paper.
Baglioni says his team has also used the nanoparticles to deacidify paintings both ancient and modern, and could help save the Vasa, a 17th-century Swedish ship that's been turned into a museum in Stockholm. That ship's acidic wood is causing it to slowly decay.
Photo of old books by Lin Pernille via Flickr