ITHACA, N.Y. -- The drizzly red-tile-roofed city of Santiago de Compostela near the northwest coast of Spain is home to a bewilderingly ornate 11th-century cathedral in which, many believe, lie the bones of St. James the Apostle. The belief that the bones carry powers of forgiveness and healing has made Santiago de Compostela the third most popular site of Christian pilgrimage in the world, surpassed only by Rome and Jerusalem. 

However, inside the cathedral itself lurks an ailment that even the bones of St. James may not be able to heal: microscopic chemical processes that threaten to corrode the more than 1,100 pipes of the cathedral's giant, elaborate, Baroque-era organ. The instrument, which was built in the early 1700s, is not alone. Corrosion is threatening Baroque-era organs in churches and cathedrals across Europe. Worse yet, in many cases, the corrosion seems to have sped up significantly in recent decades.

Where St. James has failed, 28-year-old Catherine Oertel, a postdoctoral fellow in materials chemistry at Cornell University and an organist herself, may help.

Sections of pipes from a similar, smaller organ in the convent of Santa Clara, just a few blocks from the cathedral, were transported to the Göteborg Organ Art Center (GOArt) in Sweden. There, Oertel spent three months last fall working with scientists from nearby Chalmers University of Technology to determine the cause of the corrosion and to prescribe a means of restoration and preservation. She has since brought samples to her Cornell laboratory to continue her investigation with her adviser, Shefford Baker, associate professor of materials science and engineering. 

"These instruments are really endangered species," says Oertel, referring to the Baroque-period organs once used by such titans as J.S. Bach, Johann Pachelbel and Dietrich Buxtehude. "At one time there were hundreds of organs like this, but now the number left that truly represent the original craftsmanship is pretty small." Corrosion is not the only culprit, she points out. Alterations, poor restorations and 20th-century wartime bombings are all blameworthy. There are even tales of organ pipes being melted down to make bullets.

These days, however, the chief concern is accelerating corrosion. "At first everyone jumped in and said it was industrial air pollution -- like sulfur dioxide and nitrogen-oxygen compounds," explains Oertel. "But in 2002, scientists at GOArt and Chalmers discovered that, at least for pure lead pipes, it was actually natural wood acids from the organs' own casings that have been causing most of the damage."

As wood ages, she elaborates, the cellulose in its cell walls tends to break down, emitting small molecules that include acetic acid and formic acid. When the organ is played, the acid molecules get blown into the pipes, where they start their attack.

"You might say, 'but the woods have been there all along,'" Oertel says. However, many churches in Europe have installed central heating, which could increase the rate of release of the acids from the wood and could also speed up the corrosive reaction between the acids and the metals. Additionally, in modern restoration efforts, sections of organs' casings have often been replaced with new wood, which she calls "just a fresh supply of acids." 

With original historic pipe samples like those from Santiago de Compostela, Oertel must be careful to use nondestructive methods of analysis. One of her favorite tools is the electron microprobe, which bombards the pipe with a harmless stream of electrons, causing different elements in the metal to emit X-rays of different wavelengths, revealing the pipe's composition. While past research in Sweden focused only on pure lead pipes, Oertel is extending that work to include pipes with up to 10 percent tin, and in the future, she hopes to go up to 100 percent tin.

Once she knows the composition, Oertel uses copies of the pipes made by engineers at GOArt out of new metals, on which she is free to experiment more aggressively. One procedure involves exposing the pipe directly to acetic acid vapors and cutting cross-sections into the corroded area using ion-beam milling. She can then peer at the cross-section with an electron microscope.

"To summarize my results so far, I would say that for alloys containing small amounts of tin, wood acid still seems to be the main problem," she says.

Oertel has been discussing two possible solutions with organ builders at GOArt: special coatings for the woods to trap the acids and passive air filtration systems that would not block the air flow needed for playing.

"These results may be interesting scientifically, but they aren't important unless they are shared with those who can implement them," stresses Oertel. Which is why, in addition to the typical scientific venues, she plans to publish her results in trade journals that are read by woodworkers and metalworkers, such as those at GOArt. 

Oertel, who completed her Ph.D. in chemistry and chemical biology at Cornell in January, first came up with the idea of combining her love of organ playing with her love of chemistry when she met workers from GOArt who came to Cornell in 2003 to install a Baroque-style organ they had built for Barnes Hall. She presented the idea to the National Science Foundation's Discovery Corps Fellowship Program, which awarded her funding for two years. 

In January 2006, shortly after her funding ends, Oertel will begin a job as an assistant professor of chemistry at Oberlin College in Ohio, where she first "met the organ" as an undergraduate. She is not sure whether Oberlin will support continued organ pipe research, but she envisions becoming a consultant for organ-building companies.

Thomas Oberst is a writer intern with the Cornell News Service.