Q&A: How to prevent paperback books from curling

Q: How do you keep paperback (soft cover) book covers from curling?

A: Thanks to Dennis of San Francisco for e-mailing me with this question.

Dennis says his room is often cold, but it faces the sun so it heats up periodically during the day, then gets cold again. His roommate’s room is structurally similar, but the sun doesn’t shine directly into his room, and the roommate’s books don’t curl.

My theory is that with the fluctuation in heat comes a fluctuation in humidity, which causes the paper to react differently at different times of the day. Thus, the cover stresses and curls. My recommendation is for him to shade the room during the day, especially the part of the day when the sun is the most direct and hottest. That might help modify the fluctuation in humidity.

Here are some additional tips:

• Get a humidity gauge (or hydrometer) to measure humidity and monitor the room. If humidity is high – 60% is ideal for books – take action to reduce humidity, such as using a dehumidifier or heating the room.
• If the rest of the house is moderately humid and books in the other rooms don’t curl, keep the doors to the bedroom open so the air can circulate, thus reducing humidity in the affected room.
• Store books in less humid rooms (that sounds simple, but most people don’t factor humidity into deciding where to store books).
• Shelve books tightly together. Don’t shelve them so tightly that it’s difficult to pull books from the shelves, but tightly enough to force the pages shut. Too tightly against varying sized books may warp the cover and too loosely will expose more of the paper to the air.

One more point to consider:
Paperback books generally don’t do as well with temperature and humidity fluctuations as do hardcover books. That’s because paperback books are usually made with thinner paper and often with a lesser-quality paper. If you think of your books as an investment or if you want to preserve your books for a long time, consider buying hardcover instead. They’re more costly but they should last longer with good care.

Update
Dennis reports that the tips have helped:
You were right--the temperature changes were making the humidity fluctuate drastically. That, in conjunction with a small room and no air circulation, was the culprit. I wonder how students take care of their books in small dorm rooms? Well, I bought blinds for my window and keep my door open during the day, and close it when it gets colder at night. Now that the temperature doesn't swing as much, my books seem to be holding out.

Thanks for sharing your experiences, Dennis.