What Causes Old Book Smell?

atkins-bookshelf-booksAny book lover who walks into an antiquarian or used bookstore is instantly enchanted by that unmistakable smell — the rich aroma of old books. It’s hard to explain exactly — a bit of mustiness mixed with a hint of vanilla. A team of British chemists that tested the air surrounding old books using electronic sniffing equipment described the bouquet more precisely: “A combination of grassy notes with a tang of acids and a hint of vanilla over an underlying mustiness.” Bingo. This is of course, a very different smell than walking into a bookstore that sells new books. There, the bibliophile immediately detects the “new book smell.” So what exactly creates these unique smells?

The scent of a book is created by four main factors: paper (and the chemicals used to make it), ink, adhesives used to bind the book, and to a minor degree environment (the smells that paper absorbs during its lifetime). Let’s start with the paper. Paper is made of would pulp that is processed with many chemicals during its manufacturing — sodium hydroxide, hydrogen peroxide, alkyl ketene dimer (AKD), among several others. These chemicals, through their presence or reactions, contribute to the release of volatile organic compounds (VOCs) which produce unique odors. The same thing happens with the chemicals found in the ink to print the book (e.g., AKD and hydrogen peroxide) and the adhesives used to bind the book (e.g., vinyl acetate ethylene). Since new books have not absorbed much of their environment (e.g., cigar smoke, coffee, mold etc.), this is not a critical factor for new books.

When it comes to old books, things become far more interesting, chemically speaking. The most salient factor in “old book smell” is the chemical breakdown of compounds within paper due to the presence of acids in the environment. The breakdown of cellulose and lignin produces eight classes of VOCs. Chemists have identified the unique aromas of these key VOCs: benzaldehyde creates an almond scent; vanillin creates a vanilla scent; 2-ethyl hexanol creates a slightly floral scent; and ethyl benzene and toluene create sweet scents. In fact, some compounds, like furfural (which smells like almond), can even be used to determine the age of a book. Unlike a new book, an old book’s paper has had time to absorb some environmental odors (e.g., smoke, coffee, etc.) that can add to its rich aroma.

This invites the question: if they can make “new car smell” sprays, why can’t they make “old book smell” sprays? No company has actually tried and succeeded; it remains the elusive Holy Grail of the burgeoning ebook market. Until that scent is created, you will have to visit antiquarian and used bookshops to get your fix. At least it’s cheaper than crack.

Read related posts: Famous Epic Novels by the Numbers
The Surprising Original Titles of Famous Novels
Who Are the Greatest Shakespeare Characters?
The Most Influential People Who Never Lived
The Power of Literature
The Most Influential Authors
The Most Influential Characters in Literature

For further reading: www.compoundchem.com/2014/06/01/newoldbooksmell/
http://journal.chemistrycentral.com/content/6/1/42

http://pubs.acs.org/doi/abs/10.1021/ac9016049

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