Feature

News That's Fit to Print—and Preserve

How long can libraries hold on to their newspaper collections?

By
1:32pm, January 3, 2004
Sponsor Message

The daily news has been described as the first draft of history. From the assassination of President John F. Kennedy to the cloning of Dolly the sheep, newspapers record the myriad events that shape our lives. Preserving old newspapers, many would argue, is tantamount to preserving our heritage. Newsprint companies, however, take the position that yesterday's news is old news, and follow the eminently sound business practice of using the cheapest grade of paper that does the job. Today's thin gray news stock, which is just strong enough to pass through the high-speed printing machines without tearing, is an archivist's nightmare.

"Newsprint is the poster child for bad paper," says Charles Tumosa, a research chemist at the Smithsonian Center for Materials Research and Education in Suitland, Md.

To circumvent the degradation of newspaper and its chronicle of history, libraries routinely trade in their newspaper collections for microfilm versions and in the future may rely on digital versions. This practice not only saves space, but also preempts the loss of history via newsprint decomposition.

Still, none of these duplication methods can replace the intimacy that comes with viewing or handling the original newspaper, says Timothy Hughes, founder of the dealership Rare Newspapers in Williamsport, Pa. "It's one thing to look at a microfilm," he says. "It's another to pull out a 140-year-old, dusty, bound volume and literally see what you were looking for."

To increase the opportunities for such intimacy, preservation chemists such as Tumosa and his colleagues have recently begun to piece together a new picture of how newsprint ages. What they found out about newspaper is startling: A series of mechanical and chemical analyses performed on a variety of newspapers from the 1870s to the present revealed that newsprint can routinely last more than 150 years. The finding, say Tumosa and others, could prompt libraries to hold on to their newspaper collections.

From rags to riches

Until the 1880s, newspapers were printed on paper made mostly from cotton-rag fibers. The paper's naturally low acid content and the long-lasting cotton fibers permit many newspapers from the early 1800s to remain in excellent condition today. However, as literacy increased and newspapers became more widespread toward the end of the 19th century, manufacturers switched to less-expensive, wood-based paper.

Newsprint in the past 130 years has been made largely from mechanical pulp, which is produced when wood chips are ground into fibers. The process is extremely efficient—more than 90 percent of the dry weight of wood is converted into fiber-rich pulp, which eventually gets pressed into paper. However, that paper is weak compared with cotton-rag newsprint, says Art Ragauskas, a chemist at the Institute of Paper Science and Technology in Atlanta.

Another disadvantage of modern newsprint is that a wood component called lignin makes the paper discolor when exposed to light. Lignin, Ragauskas explains, contains molecular units that absorb light and initiate a cascade of chemical reactions that ultimately turns the paper yellow but doesn't affect its flexibility and strength.

For the higher-quality paper used in books and legal documents, manufacturers chemically strip the lignin from the pulp. Yellowing, however, is not an archivist's biggest worry. "Lignin is nowhere nearly as harmful as the acids [in paper]," says chemist Chandru Shahani at the Library of Congress' Preservation Research and Testing Division in Washington, D.C. Wood fibers consist of cellulose chains, which hold the newsprint together. Over time, acids in the paper slice up these chains, causing the paper literally to break apart. Scientists had attributed these acids to air pollutants interacting with moisture at the surface of the paper.

To tease out the details of this disintegration process, Shahani and his colleagues have been conducting accelerated-aging experiments. They place samples of wood-based newsprint in sealed glass tubes and put the tubes in an oven. By monitoring changes in the paper at different temperatures over several months and extrapolating the data to room temperature, the researchers can approximate how paper would naturally age over a century in the dark.

Recently, Shahani was surprised to find the paper in the glass tubes generating copious amounts of its own acid. It has long been known that paper becomes more acidic over time, he says.

Although pollutants interacting with moisture in the air indeed form acidic molecules around the edges of paper, which crumble and discolor over time, internally, the build up of weaker acids cause more harm. "Normally these acids are not that aggressive," says Shahani. But in large quantities, he says, they can do a lot of damage.

The acid-forming process within paper begins when water molecules in the air react with the ends of the cellulose chains exposed at the surface. The reaction yields aldehydes. These compounds get oxidized in the paper to form lactic, acetic, formic, and other weak acids. As the weak acids accumulate, they break down cellulose even further and the degradation of paper increases exponentially.

The effect takes place in cotton-rag paper, too, although more slowly than in newsprint because rag paper has longer cellulose chains and therefore fewer chain ends to react with water and generate acid, says Shahani. Once, while working at the National Archives, he and his colleagues found that rag paper in bound volumes weakens more quickly than does rag paper loosely stored in boxes punctured by finger holes. The increased air circulation around the unbound pages releases acids from the paper's surface, Shahani explains.

Time will tell

Going beyond laboratory experiments, Tumosa set out to learn what was happening to newspaper living and dying in the real world of closets and bookshelves. So, he and his colleagues contacted newspaper dealers and browsed flea markets. "We rummaged in the basement, we rummaged in the attic, we got people to give us newspapers," Tumosa says. "It sort of took on a life of its own."

After the researchers amassed a collection of U.S. newspapers dating back to the early 19th century, they focused on 25 wood-based papers from 1875 to 2003.

To measure mechanical properties, the researchers cut a narrow, 5-inch-long sample from each issue, placed the strip between two clamps, and gradually stretched the paper until it broke.

Older newspapers were less extensible than young newspapers were, says Tumosa. The distance that each sample stretched before giving way indicates the structural integrity of the paper.

As paper ages, it also loses its plasticity or ability to be stretched or folded. Stretch young paper, let it go, and the paper remains permanently elongated. Pull on older paper, however, and it will break. By the time a paper reaches 80 years of age, it has entirely lost its plasticity.

"You can handle that paper, turn the pages, or take photographs of it, but if you fold the edges over, the paper will break," says Tumosa.

Not until after 100 years does the complete breakdown of newspapers begin to take effect, he notes.

Tumosa and his colleagues set out to unveil the chemistry underlying age-related changes in the papers' mechanical properties. The paper starts to lose its capacity to be extended or deformed when surface cellulose fibers degrade. Cellulose polymers are essentially long chains of glucose molecules. When the chains break down, they release glucose. The Smithsonian team measured the glucose in each of its paper samples and found that the older the paper, the higher its glucose content. When the researchers correlated this result with their mechanical data, they concluded that the more sugar present, the weaker the paper.

When large amounts of glucose are present, "the whole paper starts to come apart," Tumosa says. At that point, the glucose is coming from cellulose both at the fiber's surface and in its interior.

With their degradation model, which plots the age of paper against sugar content for each of the 25 newspapers analyzed in the study, the researchers could predict a given newspaper's life span on the basis of the amount of sugar it contains.

Although the majority of papers followed the general trend, newspapers printed around World War I had higher sugar concentrations than did older papers from the late 19th century. "We don't know exactly what happened here, but it could be they started running thinner papers or used a different process," says Tumosa.

The researchers detected a more recent anomaly in another chemical trend. "We call that the USA Today effect," says co investigator Kathy Hufford. In 1982, USA Today broke ground by running color photographs, and other papers followed suit. The colored inks require a different quality of paper. Around this time, recycled papers also entered the mix.

Paper companies have tended to be cagey about their processes, Tumosa notes. "There's a lot of history here that we're going to have to unravel," he says.

Best practices

Given that the researchers have found newsprint in the wild that has survived for more than 100 years, Tumosa suspects that newspapers could survive an additional 50 to 100 years if they were stored appropriately. His research over several years indicates that keeping papers in a dark room at 55°F and between 30 percent and 50 percent relative humidity protects the material.

These conditions have been used to preserve books and other nonnewsprint documents.

However, many librarians assume that newsprint rapidly deteriorates. The traditional method used to determine when paper documents are no longer useable is called the "double-fold test." A librarian will take the corner of a page and fold it over twice to see whether it breaks off. If it does, the document can no longer be lent out. Tumosa argues that material that fails this test can last for decades, even if it's handled.

Since the introduction of microfilm in the 1930s, many institutions have thrown out their original newspaper collections or sold them to dealers. Microfilm became widespread in the 1970s.

Indeed, newspapers take up a huge amount of space. The Library of Congress, which receives more than 1,000 newspapers from around the world, generally stores hard copies only until microfilm versions are available. "We do retain issues that document important events," adds Mark Sweeney, chief of the Preservation Reformatting Division at the Library of Congress.

Yet microfilm has its own problems. Until recently, microfilms were made of acetate, and they have already begun to fade, spot, and decompose. Although microfilm manufacturers have switched in recent years to more stable, polyester-based materials that could last beyond 100 years, other complications remain. The quality of microfilm is highly variable, says Tumosa. And the images are only black and white.

Storing existing newspapers in digital format could solve many of these problems. However, the costs of the necessary hardware and software make it prohibitive, at least in the near future.

Sweeney says that one has to consider the cost of scanning the images, either the original or the microfilm, creating search and retrieval software, and managing the long-term storage of archival data.

Tumosa admits that all newsprint will have to be stored eventually in a different format to preserve the documents far into the future. "But it is not an immediate problem unless the papers are more than 100 years old," he says. "Newspapers are not as fragile as people think."

Although space considerations might dictate whether a particular librarian chooses to keep or discard these collections, he adds, the assumption that the papers will necessarily degrade in short order is no longer defensible.

****************

If you have a comment on this article that you would like considered for publication in Science News, send it to editors@sciencenews.org. Please include your name and location.


More from Science News