Ancient Organs Focus of Corrosion Study
An organ-playing chemist has found a way to combine her passions for music and science by studying corrosion in centuries-old organ pipes.
Ancient organ pipes throughout Europe are suffering corrosion damage—so much so that some instruments can no longer produce sound.
One chemistry professor, who also happens to be an avid organist, set out to determine the cause.
Half Million for Organ Research
Catherine Oertel, assistant professor of chemistry and biochemistry at Oberlin College & Conservatory in Ohio, received a five-year grant of nearly $475,000 to study the corrosion of historic Baroque organ pipes using laboratory exposure experiments.
Supported by the grant, awarded in 2012, undergraduate researchers collaborated with Oertel to analyze authentic pipe samples and the synthesis of corrosion products and related compounds.
Dr. Catherine Oertel's work combines chemisty and materials science. Her focus: corrosion in centuries-old organs.
The funding is from the National Science Foundation's Faculty Early Career Development Program (CAREER), which grants money to teacher-scholars who integrate research and education into their work.
"My research brings something new to the chemistry department because there's an emphasis on materials research, which is at the interface of chemistry and engineering," Oertel said after she was awarded the grant.
"This work is different than pure chemistry. There's a growing interest among Oberlin students to engage in multidisciplinary study."
Oertel joined the Oberlin chemistry and biochemistry faculty in 2006. She holds a Ph.D. from Cornell University.
Tin vs. Lead
As an undergraduate at Oberlin, she became fascinated with organs after listening to recitals at the school and later decided take organ lessons for fun. She became fascinated by the way the centuries-old organ pipes were corroding and was later awarded a National Science Foundation Discovery Corps fellowship to work with a corrosion chemistry group at the Göteborg Organ Art Center (GOArt) in Sweden.
At GOArt, organ builders and scientists at the Chalmers University of Technology collaborate on researching compositions, physical properties, and corrosion of organ pipe metal.
A pipe from a 1637 organ shows major corrosion damage. Some researchers believe that tin additives in lead pipes helped protect them from corrosion.
In her research, Oertel noted that organ pipes have a variety of lead-tin alloy compositions, ranging from pure lead to pure tin, and atmospheric corrosion from acetic acid and other woods acids has been a major cause of deterioration.
Field studies previously conducted by the European Commission-funded Corrosion Of Lead and Lead-tin Alloys of organ PipeS in Europe (COLLAPSE) led some researchers to believe that lead pipes gained some corrosion protection from tin additives.
Corrosion Layer Analysis
Oertel and her team decided to test this tin theory, setting up a series of laboratory exposure experiments and analyzing the resulting corrosion layers.
The researchers placed small samples of lead alloyed with as much as 15 percent tin in glass canisters and let the samples sit in acetic acid fumes for up to a month. Some of the canisters were set at 60 percent humidity and others at 95 percent.
Lead-tin samples showed dramatically less corrosion than pure lead ones at low humidity, Oertel's research found. At high humidity, the lead-tin squares were covered in clusters of corrosion.
After performing X-ray analysis, the team found that the presence of tin particles actually lost its protective ability when exposed to high-moisture conditions.
Since organ caretakers often use humidifiers to keep the instrument's wood from cracking, the humidity issue is important to understand, Oertel said.
While in Germany last summer, Oertel had the opportunity to play an organ from the 1600s, she told The Plain Dealer.
"In Germany in the 1600s and 1700s, there would have been hundreds of organs like this," said Oertel. But now, "these organs are the endangered species of the musical world."
The research, which Oertel described as "a deeply satisfying project," is ongoing and will look at other combinations of metals that are at risk for corrosion.