The Science Behind That 'Old Book Smell'

Walking in the confines of the rare book room of the library or your local bookstore, you've smelled it. You've also smelled it upon opening a dust-covered box full of books kept in the attic or basement. Even flipping through your grandmother's old crochet books, you've smelled it. It's that "old book smell," and it's unmistakable. But why, exactly, do old books smell that way?

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In recent years, specialists have uncovered the science behind that distinct smell. Specifically, chemists have identified 15 volatile organic compounds (VOCs) that are often present in books and that degrade - emitting a gas while doing so - at a predictable rate. These compounds are in the ink, paper, and glue of books. As books age, these compounds break down, releasing the scent book lovers know.

The most common VOC that's in books is lignin. It "is present in all wood-based paper [and] is closely related to vanillin," said the International League for Antiquarian Booksellers. "As it breaks down, the lignin grants old books that faint vanilla scent." In addition to vanilla, chemists have picked up the scent of grass in aging books. "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," said Matija Strlic, a chemist at University College London and lead author of the study of that old book smell.

Despite all this talk of notes, it's not a scent that can be easily bottled. No matter, though. That old book smell is still savored by - and is a comfort to - those of us who find ourselves surrounded by books.