“This book stinks!” is really a bad review. But even a classic work can start to smell when it gets old enough. Now chemists have developed a technique that identifies what kind of degradation process an old book or historical document is going through, based on the odors it gives off. The report appears in the American Chemical Society journal Analytical Chemistry.

An old book’s familiar musty smell is due to hundreds of different volatile organic compounds gassing out from the paper and other materials, such as the binding. The particular blend of compounds results from specific degradation pathways. Conventional analysis techniques require small samples of the work for testing, further damaging the book. But analyzing the gases coming off of the old books is noninvasive.

The researchers identified 15 organic compounds that made good markers to track the condition of books. They note that their system could be used to evaluate the type of document, its present condition and its likely future, thus helping preservationists map a strategy to save historical works.

—Steve Mirsky

[The above text is an exact transcript of the audio in the podcast.]