What Causes the Smell of New and Old Books? | Hacker News Reader

What Causes the Smell of New and Old Books?

compoundchem.com

76 pointshomarp21 comments

Interesting. The furfural comes from cellulose degradation I assume. And the vanillin must come from lignin. The toluene and ethylbenzene are outgassing from old adhesive? Benzaldehyde could come from air oxidation of the toluene. Not sure about the 2-ethyl-hexanol, but man I used to love the faint floral odor of mixed hexanes!

It occurs to me that other things, more recently invented, will have interesting chemical-degradation smells as they age as well, that nobody has yet experienced because none of it is that old yet. E.g.:

• What does paper that was printed on by a laser printer a long time ago smell like?

• What does the ink from those Frixion pens smell like if you open a notebook written in by one after 100 years?

"A physical book is made up of organic matter that reacts with heat, light, moisture, and most importantly of all, the chemicals used in its production. And it is this unique reaction that causes the unique used books smell.... Old books release hundreds of volatile organic compounds into the air from the paper, and it is this which gives books their scent, a combination of grassy notes with a tang of acids and a hint of vanilla over an underlying mustiness." https://youtu.be/aUaInTfrDnA

> grassy notes with a tang of acids and a hint of vanilla

Soon available as a perfume to spray on your kindle. In a shop near you.

I would pay for this.

Demeter make a bunch of "fun" fragrances including "paperback": https://demeterfragrance.com/paperback.html

I like their "dirt".

I suppose this a good chance to ask: is it a good idea to try to keep old and browned books isolated from new ones? I imagine a cause of degradation is bacteria, so I worry that keeping them together will cause cross-contamination and accelerate the degradation process of new books.

Also, what other things can I do to preserve both old and new books? I sometimes clean them with alcohol which I'm not sure is a good idea. I also wrap some of them with plastic.

I tried to search the web for answers to these kinds of questions, but most results weren't very good. If there's a good place to look up/ask that sort of thing I'd like to know.

OP doesn't mention bacteria, only a gradual breakdown of paper and ink components. Bacteria might play a role in the breakdown, but I'm guessing that most of it is just a reaction with oxygen and moisture in the air. That is, unless the books are so damp that they literally rot away.

Chemicals can "infect" nearby objects, though, just like airborne bacteria. It's a well-known fact that the gas that comes out of a ripening apple causes nearby apples to ripen more quickly. Maybe a similar reaction can happen to books, especially if the breakdown products cause a change in acidity.

Some of my oldest books had small roundish marks that come out if you vigorously wipe with a wet cloth. I'm pretty sure those must be bacteria living off organic matter from the paper.

I imagine this is where the phrase "one bad apple ruins the whole batch" but it sounds like in practice, a good apple can also help get the whole batch ready, all the while getting old and tired. Not sure if there is any wisdom in that but it feels like it could have some. Something about teaching and getting old doing so?

My old English teacher used to quip that the better the book smells, the worse the book is. I imagine that much of the old book smell (at least in a school library) comes from the many fingers that have thumbed through the book. Then again, old books in pristine condition still exude the “old book smell” (I got a 1970s-era book on compilers from the library for free in perfect condition that still smells “old”).

I’m impressed that they were able to figure out specific compounds. How would you even get started figuring out which compounds are coming from a book?

> How would you even get started figuring out which compounds are coming from a book?

I'm not a chemist, and this is just a guess, but perhaps by placing the book in a vacuum, waiting for it to outgas a bit, then analyzing the resulting "air".

Yes, something along these lines. Its called "headspace' analysis. The volatile components that come off are typically checked with GC/MS.

That sounds reasonable. The more I think about it, the more I think that they probably already had guessed which compounds might be present, and simply performed a variety of tests on the gas to determine if those compounds were present.

One way could be spectroscopy

"Error establishing a database connection"

The foulest smell of all...

http://webcache.googleusercontent.com/search?q=cache:https:/...

http://web.archive.org/web/20190304130113/https://www.compou...

The web was so much better back before you needed a "database connection" to serve 1000 words and two images.

Bad rquest

"As with all aromas, the origins can be traced back to a number of chemical constituents, so we can examine the processes and compounds that can contribute to both."

There's also the hard question of why something smells a particular way to you. This is a question arguably beyond chemistry, and (more contentiously) perhaps even beyond biology.

It's like why something that has the color red appears as red to you, while the same object might appear as blue to someone else, but since you're both referring to the same thing and using the same words for it, you normally assume you're having the same experience but there's really no way to know that you are. There's no way to inspect anyone else's experience to see if it matches your own (and even if you could, those would still be your experiences of their experiences).

With that in mind, one could ask why the smell of a rose (or of whatever chemicals make up that smell) smell the way they do (ie. why you experience them as you do). It's difficult to see how an answer based in biology or chemistry could ever answer that question.

Reply on news.ycombinator.com