鈥淎ll my genius is in my nostrils.鈥� – Friedrich Nietzche
Are you a book-sniffer? I am, along with many, many others. We can sometimes be seen in a bookstore or library, surreptitiously bending down to inhale the scent of pages. If a fellow book-sniffer sees us, they get it. IYKYK. Book-sniffing memes abound, and you can even purchase book- and bookstore-scented candles. In 2001, Japan鈥檚 Environmental Ministry released a list of the 100 best-smelling spots in their country, and the bookstore-rich Kanda area in Tokyo was part of the list. We are not alone.
It鈥檚 well-known that smell, emotion and memory are closely linked. Fortunately, it seems most people have positive memories and feelings about the book smell.
So, what causes that smell? And why do different books smell so different from each other? What鈥檚 the difference between old book smell and new book smell? Basically, it all comes down to chemistry. (To be clear, when we talk about chemicals here, we鈥檙e referring to chemicals in the sense that everything is made up of chemicals.) The chemical makeup of the materials that create books 鈥� paper, ink, adhesives 鈥� is different depending on what is used and where it鈥檚 sourced. These chemicals release volatile organic compounds into the air, and these VOCs have odors that human noses can detect.
Paper
Being the primary component of most books, it makes sense (pun intended) that the smell of paper can be affected by many factors: chemicals used to manufacture the paper, how old the paper is, whether it鈥檚 virgin or recycled.
Most paper used to print books starts as wood pulp. That wood pulp may be treated with sodium hydroxide (causes fibers in the pulp to swell), hydrogen peroxide (bleaches the paper), or alkyl ketene dimer (improves water-resistance of paper), just to name a few possibilities. The chemicals used and the combinations of those chemicals affects the combination of VOCs we smell.
Ink
Different kinds of ink are used in commercial printing, depending on the printing press and the desired final look of the book. These different inks have different smells. The UV ink used in sheetfed printing, which is the method 色情论坛 uses to print most of our books, has a notable smell that can be a little intense in large amounts but pleasant or barely perceptible on the pages of a finished book.
Old vs. New
The book smell is partially the result of decomposition. As Jude Stewart wrote in Revelations in Air: A Guidebook to Smell, 鈥淎s soon as a book or any object is made, it starts to unmake itself 鈥� a chemical process we can smell.鈥� Obviously, older books have had longer to decompose, so are more likely to release more VOCs.
Materials and manufacturing means have changed over the years. Before 1845, paper for books was made from cotton and linen rags. In the mid-1850s, a new process caused the switch to wood pulp, which was more common but created less durable paper. It also contained the chemical lignin. Lignin occurs naturally in trees and binds cellulose fibers together. As it decays, it releases the universally loved aroma molecule vanillin, which gives vanilla its scent. Unfortunately, it also causes paper to yellow and degrade much faster (although recent research questions the negative impact). The introduction of acid-free paper in the 1970s removed most lignin in books. However, modern paper still contains cellulose, which will eventually begin to degrade but at a slower rate than paper containing large amounts of lignin.
In the 1970s, a shortage of vegetable oils like linseed and soybean oil forced printers to switch from vegetable-based inks to petroleum products. Petroleum-based inks contain VOCs that can cause respiratory irritation. Workers suffered, and the inks had a negative effect on the environment. Vegetable-based inks came back into favor. 色情论坛 currently uses only vegetable-based inks and strives to minimize the release of VOCs in our printing process.
So what causes that smell?
Basically, the book smell 鈥� especially with new books 鈥� comes from a wide variety of sources. The smell of a book will be affected by where it was produced, what paper was used, which machine it was printed on, and how it was bound together. The good news? Almost all books smell great.
