Why do old books smell?
That old book smell brings back so many memories, but what creates that smell?
Every time I catch a whiff of that special old books smell, I am transported through time and space to the cool welcoming basement of The Strand Bookstore in New York City, where I spent many hot humid summer afternoons, searching for some used books I’ve never seen nor even heard of, or sitting on the cold concrete floor, reading. The smell of old books isn’t pleasant, exactly, but it is unmistakable — and powerfully evocative.
“A combination of grassy notes with a tang of acids and a hint of vanilla over an underlying mustiness,” writes an international team of chemists from University College London (UCL) and the University of Ljubljana (UL) in Slovenia in their scientific paper (doi:10.1021/ac9016049).
“[T]his unmistakable smell is as much part of the book as its contents.”
But what is the source of that smell?
Basically, a book is made of organic materials — a variety of different papers and inks, as well as glues and fibres used to bind the book together. These organic components react to heat, light and moisture in the environment and with the chemicals used to make the book itself. Specific odours are the result of the particular blend of volatile compounds released by the sum total of the book’s organic materials. These odours also include those contributed by outside influences encountered by the book during its life — influences that impart the familiar stench of old cigarettes or cigars that is often associated with old books, for example.
That old books smell is the smell of death.
The one factor that speeds a book’s death more rapidly than any other is acidity: paper that is too acidic significantly decreases a book’s lifespan. These papers are cheap and easy to mass produce. This explains why a newspaper clipping left in the pages of a book creates an ugly orange-brown stain on the book’s pages. But books have also been printed on acidic paper. Many of the books now crowding onto shelves in used bookstores were published in the 19th and 20th centuries; yellowing books with brown spots and crackling bindings that were mass printed on cheap paper that was too acidic. These books are ageing rapidly whilst much older books are still in good shape because the paper they were printed on was much purer.
But how can these books be preserved? And how would a person know how to best store a particular book or document if they don’t know precisely what it is printed on?
Currently, we identify which materials are in a book or other printed document through analysing the compounds that burn off when a piece of that item is destroyed. But the UCL-UL team is developing a new, nondestructive, methodology where special equipment is used to mechanically “sniff” aromas released by old books and other heritage objects to identify the materials they are made of and also to assess degradation. They call this new field of study “degradomics”. The authors of this paper suggest that developing “sniff” equipment will be very useful for libraries, museums, archives and galleries to monitor the health of their collections and to help optimise storage of these items.
Here’s the video that alerted me to this paper:
Strlič, M., Thomas, J., Trafela, T., Cséfalvayová, L., Kralj Cigić, I., Kolar, J., & Cassar, M. (2009). Material Degradomics: On the Smell of Old Books. Analytical Chemistry, 81 (20), 8617–8622 doi:10.1021/ac9016049
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Originally published at The Guardian on 1 May 2012.