We have mentioned books a few times over the past three years. Having information written down means that you don't have to remember everything that you might possibly need to know in the future, and also makes it easier to teach future generations things that you may not be an expert on. Printed material will outlast most single forms of digital recording, and it doesn't require electricity or a machine to read. Books are clearly important to long-term prepping, but how do you safely store them for future use?
Storing anything begins with identifying what you need to prevent and then figuring out a way to achieve that goal.
Actual water spilled on a book is bad, but high humidity is actually worse: a book that has been wet can usually be carefully dried out, but the mold and mildew caused by high humidity is next to impossible to remove.
Keep books and their containers off of the floor (especially concrete floors) to prevent condensation from making them damp. Plastic containers will keep water out, but can also trap water within if you put away a book that is damp. If using air-tight storage, desiccant packs should be added to absorb any moisture.
Silverfish and roaches are the main adult insects to watch for. They are attracted to the glues used in binding books and can silently destroy a collection over time. Bookworms are the larvae of several different insects, and while not as common as they were a century ago, they can still mess up a book.
Storing books in cardboard boxes is common, but the corrugations in their construction and the starch used to make the cardboard turn the boxes a combination hotel and buffet for roaches and silverfish. Diatomaceous earth is a good way to control insects of all kinds, but remember that it is abrasive and may damage the books if there is a lot of vibration. Keeping the boxes slightly separated and off of the floor will also reduce the presence of roaches.
The ultraviolet portion of sunlight has a strong bleaching effect on most things; paper and ink are not immune. I've seen books left on the dash of a car for as little as two weeks that have started to show damage from sunlight. Modern inks are good, but some of them are not as permanent as the old formulas.
Never build shelves or cases where they will be subjected to full sunlight. Put books away when not in use, since leaving them out on a table for extended times can expose them to too much sunlight.
Idiots and Children
Children who have not been taught to respect other people's things should not be left unattended around books. Idiots who have no respect for knowledge are similar to children, but some of them will actively seek to destroy what they don't understand. People who will burn books often end up burning other people.
Good locks (and controlling your guests) will go a long way in stopping these threats. Properly punishing bad behavior from either type will prevent further damage.
Most of my reference library is boxed and stored right now. Not counting the “recreational” reading (fiction and alternative science), I think I have somewhere around 250 books in my main collection and I need to start thinking about preserving them. Since some of them are already over a century old, this is going to be a it of a challenge. I may have an actual library/study in a few years if I'm lucky, and I'm already designing the bookcases -- glass-paneled doors protect books much better than simple shelves will.