Books and Their Natural Enemies
I recently realized I didn’t know as much as I thought about caring for books. As someone with several rare books, it seemed a good idea to get better informed. While the worst enemy of books is probably humans (ahem, guilty), this discussion is about natural enemies: water, heat, light, gravity, and biology.
Know about mold, I thought there was no such thing as too little humidity. That’s wrong. Hot and dry conditions will dry out leather and paper, and make them brittle. The best environment for books is cool, dry, and stable. The American Institute for Conservation of Historic and Artistic Works (AIC) recommends that regularly used book rooms should maintain a temperature of around 70 degrees, and a relative humidity of around 50% (Interestingly, this is very similar to the conditions in most data centers). Temperatures above 70 degrees and relative humidity above 60% for more than 48 hours can promote the growth of mold.
Daylight and fluorescent light both have high levels of UV radiation, which causes rapid deterioration and fading. Incandescent lights aren’t as damaging, but all light will cause some damage. Rare book conservatories often maintain full darkness, lighting only small areas where people are actively working.
Gravity is mostly a problem when books aren’t stored properly. If books are to be stored vertically on shelves, they should be squarely upright, and well supported by their neighbors. Leaning on a shelf stresses the book, deforming the spine and joints. Packing books tightly together on a shelf makes it much more likely that they will be damaged during removal. Which of us hasn’t torn a headcap while trying to slip a book out of a snug shelf? Large books are best stored laid flat in stack of less than three feet tall. Using protective padding between volumes will reduce rubbing.
Books are made of organic materials: paper, cloth, leather, and various types of glue. There are a variety of living agents that attack books. Besides mold, insects and rodents can also damage your books. Shelving books with an inch or so of bare shelf in front allows easy inspection for dust and droppings that signal their activity. Good air circulation helps prevent condensation and mold, so leaving an inch or more between your books and the back of the bookshelf also helps to protect them. Cleaning your books regularly is recommended.
Caring for books isn’t rocket science. The sources I looked at were in agreement on basic care and handling. You can find more about book care at the following places: