Whether it is a first edition Chaucerian text or a scrapbook of newspaper clippings from our high school theater das, there are certain precautions you need to take to make sure that you do not wind up with bookcases full of unreadable texts.
The first thing you need to consider I the environment that you are keeping your bookcases in. You want the humidity and temperature to be carefully regulated. You may not be able to set up an archive akin to what you would find in a museum archive but you can get a combination hygrometer and thermometer for the room you are keeping those book cases in. If you get humidity control units and set it to the proper level, that should be good enough and discourage the hatching of book worms.
Yes, book worms. They are real things and the first time you see the damage they can do to price less books will stick with you and never leave your head. They can only thrive in certain conditions but the second you see any damage from them, you need to check your entire collection and quarantine the culprits.
One of the most overlooked considerations is the book cases that you use. You want to avoid anything with a heavy or overly fresh stain. If you don’t mind the look of them there is a reason that most archives use non-reactive, steel bookcases. It’s surprising how much damage a little contact with the wrong materials can do to an old book.
Make sure that everything the books come in contact with is clean and non-reactive. That means that you should use acid free archive paper in between the books. This is especially important if they are leather bound. Leather is surprisingly acidic and it can do damage to the other books in the bookcases.

