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[[{"type":"media","view_mode":"media_large","fid":"39290","attributes":{"class":"media-image","typeof":"foaf:Image","style":"","alt":"Never Stop Asking Why: Why do old books smell old?"}}]]When you crack open the spine of a new or old book, do you bring the pages close to your face and take a whiff? If so, you’re guilty of being a book sniffer. You’re also not alone in this strange but common habit. There’s something about the “new-book smell” that excites any age of reader, while the “old book smell” is a nostalgic reminder that you are about to embark on a story cherished by many readers before you. But why do books smell? We discuss this scent with help from Compound Interest.
Both new and old books have an aroma because of the volatile organic compounds (VOCs) they emit. The difference, however, in their odors is caused by the difference in the compounds they contain.
Three things contribute to that crisp “new book smell” – paper, ink and book-binding adhesives. The chemicals used in manufacturing paper, such as sodium hydroxide and hydrogen peroxide, as well as ink and adhesives, cause reactions that release VOCs into the air. As the VOCs approach our nose, we are able to smell their aroma. While VOCs are always emitted, the same chemicals are not always used when manufacturing books and therefore cause new books to smell completely different despite all having that “new-book smell.”
So what makes the fresh-off-shelf “new-book smell” change to the second-hand bookstore “old-book smell’? Over time, the cellulose and lignin contained in the book’s paper begin to break down. This chemical degradation, generally called “acid hydrolysis” because of the cellulose’s reaction with surrounding acids, produces large numbers of VOCs. These new compounds are to thank for the “old-book smell.”
When it comes to these VOCs from old books, scientists have been able to pinpoint some of the scents. According to Compound Interest, “benzaldehyde adds an almond-like scent; vanillin adds a vanilla-like scent; ethyl benzene and toluene impart sweet odours; and 2-ethyl hexanol has a ‘slightly floral’ contribution. Other aldehydes and alcohols produced by these reactions have low odour thresholds.”
So as a book sniffer, whether you prefer the scent or a new or an old book, each time you get a whiff of the book you are about to read, you’ll know – that smell you smell is thanks to a multitude of volatile organic compounds.
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