Old books smell good.
This is not an observation I expected to require peer review.
It has received peer review.
Scientists have analyzed the gases emitted by aging paper. They have identified individual compounds contributing to the smell. They have even investigated whether those compounds can tell us something about the condition of historic books.
Someone made a Historic Book Odour Wheel.
I would like to shake that person's hand.
But first:
Why do old books smell so good?
Your Book Is Slowly Falling Apart
Let's begin with the slightly grim answer.
That wonderful old-book smell is, at least partly, the smell of a book chemically breaking down.
Paper is primarily made of cellulose, along with varying amounts of lignin and other materials. As those materials age and degrade, chemical reactions produce volatile organic compounds, or VOCs.¹
Those compounds enter the air.
You inhale them.
Congratulations.
You are smelling decomposition.
Fortunately, decomposition can apparently smell lovely.
Researchers have identified compounds associated with vanilla, almond, wood, smoke, earth and must among the aromas of historic paper.²
So “old book smell” isn't really one smell at all.
It's a chemical bouquet produced by materials changing over time.
Where Have You BEEN?
Not all old books smell the same because every book has an olfactory biography.
Its smell depends partly on what it was made from: paper, fibers, inks, adhesives and bindings.
Then there is everything that happened afterward.
Where was it stored? How hot or humid did it get? Was it exposed to smoke or mold? Was it carefully preserved or shoved into someone's attic for forty years beside a box of Christmas decorations and a tax return from 1987?
Researchers can even detect volatile compounds associated with microbial activity in paper.³
The smell of an old book isn't simply telling you:
I am old.
It's also telling you:
Things have happened to me.
I love this.
Can Science Sniff a Book?
Sort of.
Researchers can collect and analyze the VOCs emitted by books without removing a piece of the object itself, which makes them potentially useful for studying valuable historic materials.
A landmark 2009 study found that those emissions could provide information about paper acidity, lignin content and cellulose degradation.¹ More recent research has even used VOC profiles to statistically distinguish groups of books from different historical periods.⁴
So no, a scientist cannot take one dramatic sniff and announce:
“1847.”
But the invisible cloud surrounding a book can contain clues about its age, materials and condition.
Even more surprisingly, older doesn't necessarily mean more deteriorated. A centuries-old book made from durable rag paper may have aged more gracefully than a much younger book made from less stable wood-pulp paper.⁵
As with people, age alone turns out to be a surprisingly poor predictor of how well a book is holding up.
New Books Are Also Gassing You
Naturally, I then wondered about new-book smell.
New books release VOCs too, but from a different combination of materials and processes, including paper treatments, inks, coatings and adhesives. Studies comparing old and modern books have found substantially different chemical profiles.⁴
Which gives us an oddly satisfying distinction:
New-book smell is partly the smell of making a book.
Old-book smell is partly the smell of unmaking one.
Books are apparently overachievers.
THE HISTORIC BOOK ODOUR WHEEL
Now we arrive at the reason I am delighted this research exists.
Researchers Cecilia Bembibre and Matija Strlič wanted to know whether smell itself could be cultural heritage.
As part of their research into documenting historic odors, they studied the historic library at St Paul's Cathedral in London and created the Historic Book Odour Wheel.²
The Historic Book Odour Wheel. Bembibre, C. & Strlič, M., Smell of Heritage: A Framework for the Identification, Analysis and Archival of Historic Odours, Heritage Science 5, 2 (2017), Fig. 4. Licensed under CC BY 4.0. No changes made.
Visitors describing the library frequently used words including woody, smoky, earthy and vanilla, and more than 70 percent described the smell positively.² The researchers combined descriptions like these with chemical analysis to create a vocabulary for documenting historic smells.
Scientists essentially built a tasting wheel for old books.
Peer review looked at this and said:
Yes.
Proceed.
I have found my people.
Can You Preserve a Smell?
This is where my ridiculous question became unexpectedly interesting.
We know how to photograph a historic room. We can document its architecture, catalogue its objects and preserve its materials.
But what did it smell like?
Smell affects how we experience places, objects and memories, yet it is remarkably easy for that part of an environment to disappear.²
Move the books. Replace materials. Restore the room. Change the ventilation.
The place may look the same afterward.
But it may no longer feel the same.
Suddenly the Historic Book Odour Wheel doesn't seem ridiculous at all.
If the smell of a library is part of people's experience of that library, losing it means losing something.
Something invisible and difficult to describe.
But something real.
So Why Does It Smell So Good?
Science can explain why old books smell.
Their materials change over time, releasing compounds associated with vanilla, wood, almond, smoke, earth and other familiar aromas.
Why we like those smells is harder.
Smell is tangled up with memory and association. A scent can become connected to a person, a childhood home, a bookstore, a library, or a particular period of our lives.
So perhaps an old book has two biographies.
One belongs to the book: what it was made from, where it has been and everything that has happened to it.
The other belongs to the person smelling it.
Maybe that's why I like old-book smell so much.
Or maybe it's the vanillin.
Either way, the next time I walk into an old bookstore and immediately inhale like a lunatic, I will do so knowing that this behavior has received considerably more scientific validation than I ever expected.
Somebody made an Odour Wheel.
I rest my case.
Footnotes
1. Matija Strlič et al., “Material Degradomics: On the Smell of Old Books,” Analytical Chemistry (2009).
PubMed
2. Cecilia Bembibre and Matija Strlič, “Smell of Heritage: A Framework for the Identification, Analysis and Archival of Historic Odours,” Heritage Science (2017).
Heritage Science
3. Research examining VOCs associated with microbial degradation of historic paper.
PubMed Central
4. Research comparing VOC profiles from books of different ages.
PubMed
5. Research examining the relationship between historic paper composition and deterioration.
PubMed Central
