Why do books smell so good? Science has the answer

The smell of a book can get intoxicating.

No matter if it is old or new, a classic of literature, a science manual, or a self-help text, many times its aroma is accompanied by magic that enchants those who have it in their hands.

But why do books have such a particular smell? and why do we tend to like it so much?

Both answers are in science.

The chemistry behind the smell

“A combination of herbaceous notes, with acidic tips and a hint of vanilla over an underlying moldy smell.”

We might think it’s the description of a wine, but no, it’s Matija Strlic, professor of heritage sciences at University College London in her 2017 work “Smell of Heritage: A Framework for the Identification, Analysis, and Archiving of Historical Smells.”

And they smell like this from the degradation over time of certain products that form the paper, especially lignin.

“Lignin is a natural biopolymer, one of the main components of plant biomass. That is to say that it is present in trees, shrubs, and plants,” Marcelo Domine, Ph.D. in Chemistry, told BBC Mundo.

“In general, vegetables have three main components, which are cellulose, hemicellulose, and lignin, depending on the type of plant. And lignin is what gives the vegetable stiffness to make it more resilient,” he added.© Getty Images

When the bins treat the wood to make paper, they extract the cellulose to create the pulp and remove the hemicellulose and lignin.

And they do so because the latter in particular makes it difficult to handle the paper precisely because of its natural properties of rigidity. But their separation is not total.

“During the removal of lignin, some of its essential oils remain next to the cellulose and that is what gives the characteristic aroma to the paper. The aroma that, by the way, is also used in some perfumes,” said Domine, who works at the Institute of Chemical Technology of the Polytechnic University of Valencia, Spain.

These remains of substances that remain on the paper of a book, for example, together with the passage of time, exposure to oxygen and moisture, are degrading it causing that brownish appearance and making its leaves fragile, very easy to crack.

This is what happens in libraries and archives, where certain books are no longer suitable for use by the general public.© Getty Images

“And the more intense the smell, the more unstable the paper,” Strlic told a University College London conference in 2012.

The paper contains different chemicals that the brain transforms into aromas.

Among them are vanillin, which smells of vanilla; acetic acid, the smell of which resembles vinegar; short-chain aldehydes that smell of dry grass; and benzaldehyde, to bitter almonds.

“If you combine them all, you’ll probably get something akin to a ball of ice cream with caramel. Some of these components can also be found in high-temperature processed foods, such as coffee, toast, and barbecue,” Strlic compared.© Getty Images

In the past lignin was a by-product, a waste from bins, but little by little it became something that is usable.

Today, the chemical industry transforms it into aromatic compounds such as vanillin or vanilla for the production of perfumes or into the so-called BTX (benzene, toluene, and xylene) that are then used to generate different chemicals or biofuels.

It is likely that with the technological advancement in the paper industry in the future the paper will not get old as it does today and that we will stop having books that smell like this.

But the smell of new books, a mixture of chemical components, ink, and glue, also gives us an effect beyond the strictly olfactory.

The psychology behind smell

Aromas are closely related to our emotions. And the smell of books is no exception.Bookstore "The last bookstore", in Los Angeles, California.© Analía Llorente Bookstore “The last bookstore”, in Los Angeles, California.

“It’s the same response we have when we smell a new car, which has a smell that tells us it hasn’t been used by anyone else,” neuroscientist Rachel Herz, an expert in the psychology of smell, told BBC Mundo.

And at the same time we are looking at the car.

“We have a context that tells us visually and cognitively what that smell means,” said the author of “The Scent of Desire.”

“When we buy a book we feel excited to have it and happy with that smell, which is also repeated with certain types of new books,” he said.

The smell of old books, on the other hand, also causes us well-being related to memories.

“We felt the smell of a used or old book that we just found, that we were looking for or was hiding somewhere. We smelled a little mold, from the decomposition of paper and ink, etc., and from the place where it was stored. We are holding this book that has a related smell and we are happy,” the neuroscientist described.

“Maybe you learned that smell when you were a kid when your parents took you to bookstores or libraries and that scent is very meaningful to you since childhood. Or maybe you’ve never been in one until you were an adult, so the meaning is different for you,” he said.© Getty Images

When asked about the different reading experiences between a printed book and an electronic one, the specialist stressed that technology is not necessarily harmful.

“People often resort to the convenience of downloading a book to avoid going to the store or even because it is cheaper,” he says.

“But I think that the experience we have of a real book through sight, sound and touch, and especially smell, can be something that at any time in life, no matter what our previous experience is, will be enriching,” she concluded.

This article is part of the Hay Festival Querétaro digital, a meeting of writers and thinkers that takes place from September 1 to 5, 2021.

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