Caring for Your Treasurers



Environmental Conditions

Books are composed of a variety of materials: paper, cloth, leather, paste, and glue. These, like all organic materials, are vulnerable to conditions and changes in the environment in which they are kept. Key factors are light, temperature, and humidity.


Similarly, books should not be exposed to rapid changes or extremes in temperature and humidity. Hot and dry conditions will desiccate and embrittle leather and paper; damp conditions will encourage mold growth. Therefore books should not be kept near sources of heat, such as radiators or fireplaces. Bookshelves should not be placed against outside walls, where pockets of cool damp air can develop. Air conditioners, dehumidifiers, and humidifiers can be used to remove or add moisture or heat. A cool, dry, and stable environment is ideal. Where the book rooms are in regular use, around 70 degrees Fahrenheit and 50 percent relative humidity is recommended.


It is extremely important that books stood vertically on shelves are squarely upright and firmly supported by neighboring books or by bookends. Leaning at an angle puts stress on the entire book structure, deforming the spine and the joints where the covers are attached. Bookends must be stable and smooth so as not to damage the covers. Books should not be packed together so tightly,however, that they are difficult to remove without causing damage. Large,oversized books are best laid horizontally in stacks of no more than two or three high. Protective pads, such as squares of polyester felt, may be placed between stacked books to prevent them from rubbing.

Books on a shelf should be kept an inch or so back from the edge. The bare ledge of shelf will show up dust and droppings signaling insect activity. However books should not be pushed to the back of the shelf. Good air circulation is imperative to prevent stagnant air pockets where condensation will collect and mold will grow.




Many book materials are attractive to pests. Rats and mice, silverfish, and a host of smaller insects are common troublemakers. Watch carefully for signs of their presence. Vigilant housekeeping discourages them. If there is an infestation, consult a conservator.

Handling and Use

Most books are not museum objects: their purpose is to be used and read.The handling of books, however, provides opportunities for accidental damage.

Handle books only with freshly washed hands. Most of the dirt on book covers and pages is accumulated grime from oily fingerprints. While invisible initially, finger grease becomes all too visible as it oxidizes and collects dirt.Wearing white cotton gloves for handling rare bindings is a good preventive measure, but turning fragile or brittle pages with gloves may cause damage and is not advised.


Avoid carrying tall, unstable stacks of books that may fall. If it is necessary to transport more books than can be held securely in two hands, pack them snugly in boxes to prevent shifting and sliding. Never pack or shelve books fore edge down as this position suspends the entire weight of the book from its joints and pulls the text block out of its cover.

A book is designed to be cradled in the reader’s hands or lap; in this position very little stress is put on its spine or joints. Placing a book flat on a table can put tremendous stress on the structure, flattening the spine and stretching the joints. If a book must be opened on a flat surface, protect both covers by placing a support, such as another book, on either side.Alternatively, cradle the book in a towel with the two ends rolled up to support the covers.


Other important tips: Use pencil, never pens (especially ball point and felt tip pens) on books as ink may run, bleed, or transfer onto other pages. Use only paper bookmarks, rather than metal or leather, which will tear or stain the pages.Avoid paper clips and other mechanical fasteners. Do not use the popular self-sticking memo slips as these leave an invisible residue of adhesive on the page to attract dirt.Avoid storing newspaper clippings, flowers, letters, or other miscellaneous material in books as they leave stains and stress the binding. And of course avoid eating, drinking, and smoking around books as the spills and stains are generally permanent.

Cleaning and Maintenance



In the past, leather books were often oiled to improve their feel and appearance. Unfortunately this can also cause stains, make the leather sticky, and degrade paper. Recent tests have shown that dressings are only cosmetic and do nothing to prolong the life of the leather. Consult a conservator before using dressings on books.

Emergencies and Minor Disasters

If books get wet, the affected material needs to be stabilized as rapidly as possible to avoid further damage. Mold growth is likely if the temperature is over 70 degrees and the relative humidity is over 60 percent for more than 48 hours. Wet books may be frozen to stabilize them; they can be thawed and dried at a later time. Wrap individual books in paper or interleave large numbers of books with paper. Pack each book’s spine down in waterproof containers or cardboard boxes lined with plastic. Freeze the books as rapidly as possible in a commercial freezer, a home freezer (for a few books), or outdoors if conditions are right. There are commercial companies that specialize in the salvage and treatment of books in large-scale 
water disasters.


When to Consult a Conservator

Problems that are beyond an owner’s capabilities should be referred to a conservator.

Use our Find a Conservator tool to search for a book and paper conservator near you.

Note: the recommendations in this guide are intended for guidance only, and AIC does not assume responsibility or liability.