Caring for Old Books: Part One
This article originally appeared in Exchange,
a newsletter published by the Wisconsin
Historical Society. (Volume 27, Number
1, Jan/Feb 1985) It is the 20th in a
series of articles titled Conservation Corner.
The series features information about maintaining
an adequate environment for the storage and exhibition
of historical collections, employing proper collection
care techniques, and recording and cataloging historical
collections.
It was written by Michael Edmonds, deputy administrator
of the Wisconsin Historical Society's library and
archives.
Valuable old books, like everything else, fall apart. They are constantly
under attack by mold, insects, environmental conditions, and the wear
and tear of everyday use. They are also slowly self-destructing from
purely internal causes. By understanding their main adversaries and
observing a few basic conservation rules, you can prolong their lives
for many decades.
Old books face three silent but deadly enemies: heat, humidity and light. Books are made mostly of paper, which is composed of long, thin fibers of cellulose. As the temperature of the air rises and falls, these fibers expand or contract. Many of them break under this stress, causing the pages to become brittle and the books to crumble. The single most useful thing you can do to preserve your old books is to store them in a place where the temperature is constant. Luckily for us, 65 to 70 degrees is the temperature they like best. But don't store them above heating vents, near drafty windows and fireplaces, or in other spots where the temperature goes up and down.
Humidity attacks books in several ways. When your books were originally manufactured, various chemicals were added to the paper to bleach it or to harden its surface. Ever since then, these chemicals have been combining with the moisture in the air to create harsh acids which eat through the cellulose fibers. Pollutants in the air also combine with moisture to make new acids that further weaken the paper. Mold spores, which normally lie dormant in the atmosphere, spring to life under warm, humid conditions and spot your pages with smelly brown and grey blotches. Extremes of humidity can even cause the covers of books to warp and labels or endpapers to lift off.
You can avoid these effects of humidity by stabilizing the moisture
level in the air at about 50 percent. The easiest way
to do this is to maintain a constant temperature of
about 65 or 70 degrees, since the humidity level rises
with the heat. A commercial window-sized air conditioner
will help keep the temperature down in warm weather,
and will also filter out many of the acidic pollutants
in the air. In the winter, putting pans of water on
radiators or registers (just like you do at home) will help keep the
air in your library from drying out too much. A Taylor gauge to measure
temperature and humidity (available at a hardware store) costs only
a few dollars and will help you regulate the moisture level more precisely.
Light is the third enemy of old books. The worst offender is direct
sunlight which will cause the dyes in binding and printing materials
to fade and will raise the temperature of the air. Keep the shades
drawn whenever possible. Even flourescent and incandescent bulbs are
harmful to paper. Like sunlight, they also contain ultra-violet rays
that speed up the action of the acids and make the paper brittle and
brown. Keep the lights in your book areas turned off when they're
not needed. You can also buy ultraviolet filters for windows and flourescent
lights in areas that cannot be kept shaded.
Perhaps in a conservator's ideal world, our old and valuable volumes would always be kept in a pitch dark room where the temperature was always 68 degrees and the humidity level 50%. But in reality, our old volumes must be shelved, leafed through, checked out, read, photocopied, reshelved, etc., and all this takes a toll on their physical health.
To minimize the damage caused by everyday use you should first create an awareness of preservation issues in your staff and volunteers. Watch out for delicate materials and restrict their use when necessary. Don't hesitate to remove old and fragile items from circulation, to supervise their use closely, or to prohibit them from being photocopied. Most patrons understand why special care is sometimes needed.
By carrying out the suggestions above and using your common sense, you can protect your old and precious volumes from most of their enemies. In Caring for Old Books: Part Two I'll detail some basic principles and techniques of book restoration and give you suggestions of where to turn for more information and supplies.
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