Establishing the condition of old books and precious historical documents traditionally involves removing samples of the paper from the valuable archival materials for testing in a laboratory. Naturally such destructive forms of testing are far from ideal. Now scientists have come up with a better option with the development of a nondestructive “sniff” test that can measure the degradation of old books and documents based on their smell.

The familiar musty smell of an old book is the result of hundreds of so-called volatile organic compounds (VOCs) being released into the air from the paper as readers leaf through the pages. According to Matija Strlic from University College London, those substances hold clues to the paper’s condition and she and her colleagues identified 15 VOCs that seem good candidates as markers to track the degradation of paper in order to optimize their preservation.

The used the new technique, called "material degradomics," to analyze the gases emitted by 72 historical papers from the 19th and 20th centuries, including papers containing rosin (pine tar) and wood fiber, which are the most rapidly degrading paper types in old books. In addition to being useful for assessing the condition of books and documents, the researchers say the method could also be used to help preserve other historic artifacts.

The study, "Material Degradomics: On the Smell of Old Books", appears in the journal Analytical Chemistry.