A Corrosive Enemy
Historic and modern organs share a common enemy: corrosion. In a surprise turnaround, scientists have discovered that the primary source of pipe corrosion is not industrial pollution, as was long thought, but the organs themselves.
Or more precisely, the acid contained in organ wood. As Catherine Oertel, assistant professor of chemistry at Oberlin College, explains, wood acid causes pipe corrosion in two ways.
First, by direct contact of pipe metal with wood, which is why the pipe racks for Cornell’s organ pipes were charred before the pipes were inserted, neutralizing the acid transfer.
But wood also excretes acid into the air in what Oertel calls “a vapor mediated process.” The acid thus gets into the bellows area and the wind channels where the air collects before moving into the pipes.
Oertel studied the problem of pipe corrosion as a post-doc at Cornell, collaborating with corrosion chemists at the Chalmers University of Technology in Sweden. She used high-power microscopes in Cornell’s nanofabrication facilities to study how different compositions of metal alloys affect corrosion rates. She found that even a small amount of added tin can reduce the susceptibility of pipes to corrosion, and that this protective effect is extremely sensitive to humidity.
Cutting-edge technology may prove corrosion’s undoing: Oertel says scientists are experimenting with nanoparticle coatings that have a basic pH, which could neutralize the acid as it’s emitted, eliminating corrosion invisibly.