the well-known musty smell of an old book is the result of hundreds of so-called volatile organic compounds (VOCs) released into the air from the paper.
The aroma of an old book is familiar to every user of a traditional library A combination of grassy notes with a tang of acids and a hint of vanilla over an underlying mustiness, this unmistakable smell is as much a part of the book as its contents.
The new technique -- an approach called "material degradomics" -- analyzes the gases emitted by old books and documents without altering the documents themselves. The scientists used it to "sniff" 72 historical papers from the 19th and 20th centuries. Some of the papers contained rosin (pine tar) and wood fiber, which are the most rapidly degrading types of paper found in old books. The scientists identified 15 VOCs that seem good candidates as markers to track the degradation of paper in order to optimize their preservation. The method also could help preserve other historic artifacts, they add.